MARK LYNAS

The God Species

How the Planet Can Survive

the Age of Humans

Dedication

For my family and other animals

Contents

Cover

Title Page

Dedication

Introduction

Chapter One - The Ascent of Man

Chapter Two - The Biodiversity Boundary

Chapter Three - The Climate Change Boundary

Chapter Four - The Nitrogen Boundary

Chapter Five - The Land Use Boundary

Chapter Six - The Freshwater Boundary

Chapter Seven - The Toxics Boundary

Chapter Eight - The Aerosols Boundary

Chapter Nine - The Ocean Acidification Boundary

Chapter Ten - The Ozone Layer Boundary

Chapter Eleven - Managing the Planet

Notes

Index

Acknowledgements

By the same author

Copyright

About the Publisher

Introduction

Then Man said: ‘Let there be life.’ And there was life.

Thunderbolts do not come much more momentous than this: in May 2010, for only the second time in 3.7 billion years, a life-form was created on planet Earth with no biological parent. Out of a collection of inanimate chemicals an animate being was forged. This transformation from non-living to living took place not in some primordial soup, still less the biblical Garden of Eden, but in a Californian laboratory. And the Divine Creator was not recognisably Godlike, despite the beard and gentle countenance. He was J. Craig Venter, a world-renowned biologist, highly successful entrepreneur and one of the first sequencers of the human genome. At the ensuing press conference, this creator and his colleagues announced to the world that they had made a self-replicating life-form out of the memory of a computer. A bacterial genome had been sequenced, digitised, modified, printed out and booted up inside an empty cell to create the first human-made organism. As proof, the scientists wielded photographs of the microscopic ‘Mycoplasma mycoides JCVI-syn1.0’ cells, busily obeying the original divine command to be fruitful and multiply in one of the J. Craig Venter Center’s many Petri dishes. The new discipline of synthetic biology had come of age.

Forget all your fears about genetic engineering; synthetic biology makes GE look as quaint and old-fashioned as a horse and cart at a Formula One rally. Old-style biotech was about mixing and rearranging small numbers of existing natural genes from different species and hoping that the right thing happened. Synthetic biology is an order of magnitude more powerful, for it gives humanity the potential to design and create life from scratch. Venter and his team didn’t quite achieve that: their synthetic genome, after being stitched together with the help of some well-trained yeast, was transplanted into the empty cell of a closely related bacterium that was arguably already ‘alive’, at least in form if not in function. But the structure the new cells took was that prescribed by the scientists, featuring specially-designed DNA ‘watermarks’ that included three quotes, the names of the researchers on the project, and an email address for anyone clever enough to successfully decode and sequence the new genome.

The next steps for Venter’s team – and other competitors rushing to pioneer novel methods in the same field – point the way towards a new technology of awesome power and potential. Once the function of every gene is understood, scientists can begin to build truly new organisms from scratch with different useful purposes in mind. Microbial life-forms could be designed to create biofuels or new vaccines, to bio-remediate polluted sites or to clean water. In the hands of a modern-day Bond villain, they might also be used to forge virulent new superbugs that could wipe out most of the world’s population. But the technology per se is ethically inert; it is just a tool. The purpose of a machine depends upon whose hands are wielding its power. Synthetic biology reduces the cell to a machine, whose components – once properly understood – can be assembled like blocks of Lego. Why build a robot out of perishable steel and plastic when you can build a bio-bot that feeds itself, carries out its prescribed task, heals any injuries, and creates near-identical copies of itself with no outside intervention?

The Book of Genesis is full of instances of Man being punished for his attempts to become like God. After the woman and the serpent combine forces to taste the forbidden fruit from one tree, in Genesis 3:22 the Lord complains: ‘See, the man has become like one of us, knowing good and evil; and now, he might reach out his hand and take also from the tree of life, and eat, and live for ever’. Man is banished from Eden to deny him this power of immortality, but Genesis 11:3 once again finds humanity trespassing on the power of the divine, this time with a great tower aimed at reaching Heaven. God’s solution to the Tower of Babel was a smart one, achieved by dividing humans into mutually uncomprehending linguistic groups. Today, with the worldwide language of science, that problem has finally been overcome. Venter and his team have seemingly proved that all life is reducible to chemistry – there is nothing more to it than that. No essential life-force, no soul, no afterlife.

With the primacy of science, there seems to be less and less room for the divine. God’s power is now increasingly being exercised by us. We are the creators of life, but we are also its destroyers. On a planetary scale, humans now assert unchallenged dominion over all living things. Our collective power already threatens or overwhelms most of the major forces of nature, from the water cycle to the circulation of major elements like nitrogen and carbon through the entire Earth system. Our pollutants have subtly changed the colour of the sky, whilst our release of half a trillion tonnes of carbon as the greenhouse gas CO₂ into the air is heating up the atmosphere, land and oceans. We have levelled forests, ploughed up the great grasslands and transformed the continents to serve our demands from sea to shining sea. Our detritus gets everywhere, from the highest mountains to the deepest oceans: abandoned plastic bags drift ghostlike in the unfathomable depths, even kilometres beneath the floating Arctic ice cap. Wherever you look, this truth is there to behold: pristine nature – Creation – has disappeared for ever.

There is a name for this new geological era. The Holocene – the 10,000-year, climatically equable post-ice age era during which human civilisation evolved and flourished – has slipped into history, to make way for the Anthropocene. For the first time since life began, a single animal is utterly dominant: the ape species Homo sapiens. Evolution has equipped us with huge brains, stunning adaptability and brilliantly successful technical prowess. In less than half a million years we have gone from prodding anthills with sticks to constructing a worldwide digital communications network. Who can beat that? Like Venter’s bacteria, we have been extremely fruitful and multiplied prodigiously: humans are now more numerous than any large land animal ever to walk the Earth, and the combined weight of our fleshy biomass outstrips that of most other larger animals put together, with the single exception of our own livestock. The productive capacity of a major part of the planet’s terrestrial surface is now dedicated to satisfying our demands for food, fuel and fibre, whilst the oceans are trawled round the clock for the fishy fats and proteins our brains and bodies demand. In sum, somewhere between a quarter and a third of the entire planetary ‘net primary productivity’ (everything produced by plants using the power of the sun) is today devoted to sustaining this one species – us.

With close to 7 billion specimens of Homo sapiens currently in existence, mostly enjoying rising (though highly variable) levels of wealth and material consumption, human beings have so far been an evolutionary success story unprecedented in the entire history of planet Earth. But there is a dark side to this momentous achievement. For the biosphere as a whole the Age of Humans has been a catastrophe. Our domestication of the planet’s surface to provide crops and animals for ourselves has displaced all competing species to the margins. The Earth is now in the throes of its sixth mass extinction, the worst since the ecological calamity that wiped out the dinosaurs 65 million years ago. Evolution is about competition – and we have outcompeted them all. No other species can control our numbers and return balance to the system (though extremely virulent microbes are likely to come closest). Whenever we have appeared on the verge of shortages, either in food production or fuel for our ever-rising energy demands, we have saved ourselves through brainpower and the judicious application of technology. The worst plague, flood or world war – which may singly or combined cause horrifying loss of life – is just a blip in this relentless upward trend.

But most amazing of all perhaps is how blissfully unaware of this colossal transformation we remain. We are phenomenally, stupendously, ignorant. As if God were blind, deaf and dumb, we blunder on without any apparent understanding of either our power or our potential. Even most Greens – ever hopeful that vanished wild nature can one day be restored – still recoil from the real truth about our role. Climate-change deniers are successful not just because of the moneyed vested interests they serve, but because they tap into a powerful cultural undercurrent that insists we are small and the planet is big, ergo nothing we do – not even in our collective billions – can have a planet-scale impact. The world’s major religions, founded as they were in an earlier, more innocent age, share this insistence, as if the Book of Genesis could still be anything more than a historical metaphor in an era of Earth science and biochemistry. Our culture and politics languishes decades behind our science.

To most people my contention that humans are now running the show smacks of hubris. Consequently everyone loves a good disaster, because it makes us feel small. After the 2004 Asian tsunami there were honest discussions over the benevolence or otherwise of God. Those in the path of hurricanes often speak about the anger of Mother Nature. When the Icelandic volcano Eyjafjallajokull erupted in April 2010, news reports reminded us of ‘nature’s awesome power over humans’, as if a few grounded aircraft in Europe had humbled us helpless clumsy apes. The Japanese earthquake and resulting tsunami disaster in March 2011 showed nature’s force at its most powerful and destructive, but many lives were saved because of warning systems and strict building codes. We may not be able to stop earthquakes, but the idea of perennial human victimhood is now somewhat out of date. I suspect there is a reason why most of us cannot bear to let go of it, however, for admitting that we hold the levers of power over the Earth’s major cycles would mean having to take conscious decisions about how the planet should be managed. This is an idea so difficult to contemplate that most people simply prefer denial, relieving themselves of any inconvenient burden of responsibility. What you don’t know can’t hurt you, right?

This see-no-evil approach is particularly convenient for politically motivated climate-change deniers. Take Newt Gingrich, the US Republican firebrand who almost single-handedly destroyed the Clinton presidency and is now taking aim at Obama too. He told the American environment website Grist.org in June 2010: ‘It’s an act of egotism for humans to think we’re a primary source of climate change. Look at what happened recently with the Icelandic volcano. The natural systems are so much bigger than manmade systems.’¹ QED, as I think they say.²

Gingrich and his ilk may be an extreme case, but this degree of ignorance and denial cannot go on for much longer. Instead, I suggest that since nature can no longer tame us, then we must tame ourselves. Recognising that we are now in charge – whether for good or ill – we need to take conscious and collective decisions about how far we interfere with the planet’s natural cycles and how we manage our global-scale impacts. This is not for aesthetic reasons, or because I mourn the loss of the natural age. It is too late for that now, and – as my uncle always says – one must move with the times. Instead, the overwhelming weight of scientific evidence suggests that we are fast approaching the point where our interference in the planet’s great bio-geochemical cycles is threatening to endanger the Earth system itself, and hence our own survival as a species. To avert this increasing danger, we must begin to take responsibility for our actions at a planetary scale. Nature no longer runs the Earth. We do. It is our choice what happens from here.

This book aims to demonstrate how our new task of consciously managing the planet, by far the most important effort ever undertaken by humankind, can be tackled. The idea for it came to me in a moment of revelation two years ago in Sweden, during a conference in the pretty lakeside village of Tällberg. I was invited to join a group of scientists meeting in closed session to discuss the concept of ‘planetary boundaries’, a term coined by the Swedish director of the Stockholm Resilience Centre, Professor Johan Rockström. The scientists – all world experts in their fields – were trying to nail down which parts of the Earth system were being most affected by humans, and what the implied limits might be to human activities in these areas. Some, like climate change and biodiversity loss, were familiar and obvious contenders for top-level concern. Others, like ocean acidification and the accumulation of environmental toxins, were newer and less well-understood additions to the stable.

During hours of debate, and with much scribbling of numbers and spider diagrams on flip-chart paper, humanity’s innumerable list of ecological challenges was reduced to just nine. I left the room late that afternoon certain that something radical had just happened, but not quite sure what it was. It wasn’t until later in the evening – in the shower of all places – that I understood in a flash just how important the planetary boundaries concept could be. I realised that scientists studying the Earth system were now in a position to define what mattered at a planetary level, and that this knowledge could and should be the organising basis for a new kind of environmental movement – one that left behind some of the outdated concerns of the past to focus instead on protecting the planet in the ways that really counted. Of course all knowledge is tentative, but here was something very tangible: for the first time, world experts were not just listing our problems, but putting numbers on how we should approach and solve them. I tracked down Johan Rockström and we shared a beer in the hotel lobby. He was encouraging, and we agreed that my job as a writer and as an environmentalist should be to do what the scientists could not: get this scientific knowledge out into the mainstream and demand that people – campaigners, governments, everyone – act on it. Hence this book.

The planetary boundaries concept of course builds on past work conducted by experts in many different fields, from geochemistry to marine biology. But its global approach is actually very new and potentially quite revolutionary. Unlike, say, the 1972 Limits to Growth report produced by the Club of Rome, the planetary boundaries concept does not necessarily imply any limit to human economic growth or productivity. Instead, it seeks to identify a safe space in the planetary system within which humans can operate and flourish indefinitely in whatever way they choose. Certainly this will require limiting our disturbance to key Earth-system processes – from the carbon cycle to the circulation of fresh water – but in my view this need constrain neither humanity’s potential nor its ambition. Nor does it necessarily mean ditching capitalism, the profit principle, or the market, as many of today’s campaigners demand. Above all, this is no time for pessimism: we have some very powerful tools available to allow us to live more gently on this planet, if only we choose to use them.

In this book I take the planetary boundaries concept further into the social, economic and political realms than the original experts were able to. Although some of the planetary boundaries expert group have generously helped to check my facts and figures, I do not expect them to agree with all my suggestions or arguments regarding the implications of meeting the boundaries. There are substantial caveats and uncertainties, as always, and disagreement can be expected between other experts about whether a ‘planetary boundary’ is truly relevant, and if so, what its limit should be – not to mention how we should meet it. This is first-draft work, Planetary Boundaries 1.0 if you will; there cannot fail to be teething problems. Even so, factual statements in this book are based wherever possible on the peer-reviewed scientific literature – the gold standard for current knowledge. References are at the back, and I urge all readers to make good use of them.

Many will find my analysis and conclusions rather unsettling – not least my colleagues in the Green movement, many of whose current preoccupations are shown to be ecologically wrong. Until now, environmentalism has been mostly about reducing our interference with nature. Central to the standard Green creed is the idea that playing God is dangerous. Hence the reflexive opposition to new technologies from splitting the atom to cloning cattle. My thesis is the reverse: playing God (in the sense of being intelligent designers) at a planetary level is essential if creation is not to be irreparably damaged or even destroyed by humans unwittingly deploying our new-found powers in disastrous ways. At this late stage, false humility is a more urgent danger than hubris. The truth of the Anthropocene is that the Earth is far out of balance, and we must help it regain the stability it needs to function as a self-regulating, highly dynamic and complex system. It cannot do so alone.

This means jettisoning some fairly sacred cows. Nuclear power is, as many Greens are belatedly realising, environmentally almost completely benign. (The Fukushima disaster in Japan did nothing to change this sanguine assessment, and perhaps more than anything reconfirmed it: more on that later.) Properly deployed, nuclear fission is one of the strongest weapons in our armoury against global warming, and by rejecting it in the past campaigners have unwittingly helped release tens of billions of tonnes of carbon dioxide into the atmosphere as planned nuclear plants were replaced by coal from the mid-1970s onwards. Anyone who still marches against nuclear today, as many thousands of people did in Germany following the Fukushima accident, is in my view just as bad for the climate as textbook eco-villains like the big oil companies. (Germany’s over-hasty switch-off of seven of its nuclear power plants after the Japanese tsunami will have led to an additional 8 million tonnes of carbon dioxide in just three months.³) The same goes for genetic engineering. The genetic manipulation of plants is a powerful technology that can help humanity limit its environmental impact and feed itself better in the process. I personally campaigned against it in the past, and now realise that this was a well-intentioned but ignorant mistake. The potential of synthetic biology I can only begin to guess at today in early 2011. But the lesson is clear: we cannot afford to foreclose powerful technological options like nuclear, synthetic biology and GE because of Luddite prejudice and ideological inertia.

Indeed, if we apply the metric of the planetary boundaries to the campaigns being run by the big environmental groups, we find that many of them are irrelevant or even counterproductive. Carbon offsetting is a useful short-term palliative that the Green movement has discredited without good reason, harming both the climate and the interests of poor people in the process. Some Green groups have also made it very difficult to use the climate-change negotiations as a way to save the world’s forests by insisting that rainforest protection should not be eligible for carbon credits. In addition, environmental and development NGOs in general have been much too easy on rapidly emerging big carbon emitters like China and India, whose governments need to be pressed or assisted to eschew coal in favour of cleaner alternatives. Blaming the rich countries alone for climate change may tick all the right ideological boxes, but it is far from being the full story.

Most Greens also emphatically object to geoengineering – the idea that we could consciously alter the atmosphere to counteract climate change, for example by spraying sulphates high in the stratosphere to act as a sunscreen. But the objectors seem to forget that we are already carrying out massive geoengineering every day, as a hundred million people step into their cars, a billion farmers dig their ploughs into the soil, and 10 million fishermen cast their nets. The difference seems to come down to one of intent: is unwitting and bad planetary geoengineering really better than witting and good planetary geoengineering? I am not so sure. At the very least a reflexive rejectionist position risks repeating the mistakes of the anti-genetic engineering campaign, where opposing a technology a priori meant that lots of potential benefits were stopped or delayed for no good cause. Being against something can have just as big an opportunity cost as being for it.

Certainly deciding on something as epochal as intentional climatic geoengineering would involve us in some truly awesome collective decisions, which we have only just begun to evolve the international governance structures to manage. But if we want the Anthropocene to resemble the Holocene rather than the Eocene (roughly 55–35 million years ago, which was several degrees hotter and had neither ice caps nor humans) we will need to act fast. On climate change, meeting the proposed planetary boundary means being carbon-neutral worldwide by mid-century, and carbon-negative thereafter. The former will not be possible in my view without nuclear new-build on a large scale, and the latter will need the deployment of air-capture technologies to reduce the concentration of ambient CO₂. On biodiversity loss, we need to rapidly scale up ‘payments for ecosystem services’, schemes that use private and public-sector approaches to make planetary ecological capital assets like rainforests and coral reefs worth more alive than dead. To meet the other boundaries we will need to deploy genetically engineered nitrogen- and water-efficient plants, remove unnecessary dams from rivers, eliminate the spread of environmental toxins like dioxins and PCBs, and get much better at making and respecting international treaties. We can learn a great deal from the success of ozone-layer protection, which remains a shining example of how to do it right.

Most importantly, environmentalists need to remind themselves that humans are not all bad. We evolved within this living biosphere, and we have as much right to be here as any other species. Through our intelligence, Mother Earth has seen herself whole and entire for the first time from space⁴. Thanks to us she can even hope to protect herself from extraterrestrial damage: we now operate a programme to track large meteorites like the one that destroyed a significant portion of the biosphere at the end of the Age of Dinosaurs. The Age of Humans does not have to be an era of hardship and misery for other species; we can nurture and protect as well as dominate and conquer. But in any case, the first responsibility of a conquering army is always to govern.

Chapter One

The Ascent of Man

Three large rocky planets orbit the star at the centre of our solar system: Venus, Earth and Mars. Two of them are dead: the former too hot, the latter too cold. The other is just right, and as a result has evolved into something unique within the known universe: it has come alive. As Craig Venter and his team of synthetic biologists have shown, there is nothing chemically special about life: the same elements that make up our living biosphere exist in abundance on countless other planets, our nearest neighbours included. But on Earth, these common elements – carbon, hydrogen, nitrogen, oxygen and many more – have arranged themselves into uncommon patterns. In the right conditions they can move, grow, eat and reproduce. Through natural selection, they are constantly changing, and all are involved in a delicate dance of physics, chemistry and biology that somehow keeps Earth in its Goldilocks state, allowing life in general to survive and flourish, just as it has done for billions of years.

Why the Earth has become – and has remained – a habitable planet is one of the most extraordinary stories in science. Whilst Venus fried and Mars froze, Earth somehow survived enormous swings in temperature, rebounding back into balance whatever the initial cause of the perturbation. Venus suffered a runaway greenhouse effect: its oceans boiled away and most of its carbon ended up in the planet’s atmosphere as a suffocatingly heavy blanket of carbon dioxide. Mars, on the other hand, took a different trajectory. It began life warm and wet, with abundant liquid water. Yet something went wrong: its carbon dioxide ended up trapped for ever in carbonate rocks, condemning the planet to an icy future from which there could be no return.¹ The water channels and alluvial fans that cover the planet’s surface are now freeze-dried and barren, and will remain so until the end of time.

Part of the Earth’s good fortune obviously lies in its location: it is the right distance from the sun to remain temperate and equable. But the distribution of Earthly chemicals is equally critical: our greenhouse effect is strong enough to raise the planet’s temperature by more than 30 degrees from what it would otherwise be, from –18˚C to about 15˚C today on average – perfect for abundant life – whilst keeping enough carbon locked up underground to avoid a Venusian-style runaway greenhouse. Ideologically motivated climate-change deniers may rant and obfuscate, but geology (not to mention physics) leaves no room for doubt: greenhouse gases, principally carbon dioxide (with water vapour as a reinforcing feedback), are unquestionably a planet’s main thermostat, determining the energy balance of the whole planetary system.

This astounding 4-billion-year track record of self-regulating success makes the Earth unique certainly in the solar system and possibly the entire universe. The only plausible explanation is that self-regulation is somehow an emergent property of the system; negative feedbacks overwhelm positive ones and tend to push the Earth towards stability and balance. This concept is a central plank of systems theory, and seems to apply universally to successful complex systems from the internet to ant colonies. These systems are characterised by near-infinite complexity: all their nodes of interconnectedness cannot possibly be identified, quantified or centrally planned, yet their product as a whole tends towards balance and self-correction. The Earth that encompasses them is the most complex and bewilderingly successful system of the lot.

One of the pioneers in understanding the critical regulatory role of life within the Earth system was the brilliant scientist and inventor James Lovelock. Lovelock’s original Gaia theory – that living organisms somehow contrive to maintain the Earth in the right conditions for life – was a stunning insight. But his idea of the Earth as being alive, perhaps as a kind of super-organism, only holds good as a metaphor. Self-regulation comes about not for the benefit of any component of the system – living or non-living – but by dint of the overall system’s long-term survival and innate adaptability.

An important characteristic of the Earth system is that its main elements move around rather than all ending up in one place. Water, for instance, cycles through rivers, oceans, ice caps, the atmosphere and us. An H₂O molecule falling in a snowstorm on the rocky peak of Mount Kenya may have been exhaled in the dying gasps of Queen Elizabeth I: water, driven by energy, is always circulating. Nitrogen, oxygen, phosphorus, sodium, iron, calcium, sulphur and other elements are also perpetually on the move. Carbon is perhaps the most important cycle of all, because of the thermostatic role played by its molecular state; particularly in its gaseous form as CO₂, but also in combination with other elements, such as with hydrogen as CH₄ (methane). It was the failure of the carbon cycle that doomed Venus and Mars, yet here on Earth various feedbacks have kept the system in relative balance for billions of years – even altering the strength of the greenhouse effect to offset the sun’s increasing output of radiation over geological time.

Over million-year timescales, the carbon cycle balances out between the weathering of rocks on land, which draws carbon dioxide out of the air, and its emission from volcanoes. Carbon is deposited in the oceans and then recycled through plate tectonics, as oceanic plates subduct under continental ones, providing more fuel for CO₂-emitting volcanoes. The process is self-correcting: if volcanoes emit too much carbon dioxide, the Earth’s atmosphere heats up, increasing weathering rates and drawing down CO₂. If carbon dioxide levels fall low enough for weathering to cease – as perhaps was the case during the early ‘snowball Earth’ episodes, when global-scale ice caps put a stop to the weathering of rocks – volcanic emissions continue uninterrupted, allowing CO₂ to build up until a stronger greenhouse effect melts the ice and allows balance to be restored. The system is stable but not in stasis: the geological record shows tremendous swings in temperature and carbon dioxide concentrations over the ages, though always within certain boundaries.

Perhaps one of the strongest arguments against the Gaia concept is the fact that even if the planet in general remains habitable, things do sometimes go badly wrong. Over the last half-billion years since complex life began there have been five serious mass extinctions, the worst of them wiping out 95 per cent of species alive at the time. Most appear to have been linked to short-circuits in the carbon cycle, where volcanic super-eruptions led to episodes of extreme global warming that left the oceans acidic and depleted in oxygen, and the land either parched or battered by merciless storms. And yet, over millions of years, new species evolved to fill the niches vacated by extinguished ones, and some kind of balance was restored. Over the last million years, recurrent ice ages demonstrate how regular cycles can lead to dramatic swings in temperature, as orbital changes in the Earth’s motion around the sun lead to small differences in temperature, which are then amplified by carbon-cycle and ice-albedo (reflectivity) feedbacks. Our planet may be self-regulating, but it is also extraordinarily dynamic.

GOD SPECIES OR REBEL ORGANISM?

Life is now an important component of most of the planet’s major cycles. The majority of carbon is locked up in calcium carbonate (limestone) rocks, laid down in the oceans by corals and plankton. The appearance of photosynthesis was perhaps one of life’s most miraculous innovations, allowing microbes – and later, green plants – to use atmospheric carbon dioxide as a source of food. Water is an essential part of the process: in cellular factories called chloroplasts, plants split water into hydrogen and oxygen, combining the hydrogen with carbon from the air to form carbohydrates, and releasing oxygen as a waste product. The process opened up an opportunity for the evolution of animals, that could eat the carbohydrates as a food source and recombine them with oxygen (forming CO₂ and water), thereby generating energy and closing the loop.

Evolution of life is a critical part of the process of planetary self-regulation, because it allows organisms to change to take advantage of new opportunities and learn from failures – evolution is self-correction in action. Just as the build-up of oxygen in the air allowed animal life to appear, so the accumulation of any waste is an opportunity for new species to evolve to take advantage of it. Evolution is very different from mere adaptability, because it allows new life-forms to appear rather than old ones to adapt, leading to much greater transformations. A species may, for example, be able to adapt to a shift in its food supply by moving, but over many millennia an entirely new species may thereby come into being, able to exploit a whole new niche in the ecosystem. Think of polar bears, likely descended from an isolated population of brown bears in an ice age, but which evolved white fur and an ice-based lifestyle to become the pre-eminent hunter of the far north.

All this sounds comforting. The Earth, and life, will always prevail. But the self-regulating system contains a flaw, one that can seriously damage or even destroy it. This flaw is the gap in time between a perturbation and the ensuing correction: instabilities can happen very fast, whilst the correcting process of self-regulation typically takes much longer. The gap between the advent of an oxygen-rich atmosphere and the appearance of animal life was a long one: a good hundred million years if not more. Major volcanic eruptions may release trillions of tonnes of carbon dioxide over just a few thousand years, outstripping the capacity of the Earth system to mop up the additional CO₂ via rock weathering and other processes of sequestration, and leading to extreme global warming events. Mass extinctions happen because changing circumstances outstrip the adaptability of existing species before evolution can work its magic. Over millions of years new species can appear, but only from the diminished gene pool of the survivors – and a return to true pre-extinction levels of biodiversity may take much longer, if it ever takes place at all.

This time-lag effect was cleverly demonstrated in a modelling simulation undertaken by two British researchers, Hywell Williams and Tim Lenton (both at the University of East Anglia; Lenton is a member of the planetary boundaries expert group).² In a computer-generated world – entirely populated by evolving micro-organisms living in a closed flask – Williams and Lenton found that the closing of nutrient loops emerged as a robust property of the system nearly every time the model was run. As in the real world, the emergence of self-regulation came about because evolution allowed new species to appear that could use the waste of one species as food for themselves, recycling nutrients and leading to a stable state. Moreover, the more species that evolved, the greater the amount of recycling and the greater the overall biomass the system could support. ‘Flask world’ had discovered the value of biodiversity.

But this world also had a dark side, for several simulations illustrated that the flaw in self-regulation – the time gap between a disturbance and the evolved correction – might occasionally be fatal. In just a few model runs, an organism appeared that was so spectacularly successful in mopping up nutrients that its numbers exploded and its wastes built up to toxic levels before other organisms were able to evolve a response. Williams and Lenton dubbed these occasional rogue species ‘rebel organisms’. They were unusual, but their impact was invariably catastrophic: the explosive initial success of the rebels changed the simulated global environment so suddenly and dramatically that their compatriots were killed, and – with no other life-forms around to recycle their wastes – they were themselves condemned to die too. As the last lonely rebels perished, their whole biosphere went extinct, evolution ceased, self-regulation failed, and life wiped itself out.

Like Lovelock’s Gaia, Flask world – and its rebel organisms – might just be a clever idea, more of a metaphor than a true representation of reality. But the parallels with our species are unsettling. We have transformed our environment within just a few centuries in ways that are wiping out other life-forms at a shocking speed – the changes so rapid that evolution has no time to adapt and thereby allow other organisms to survive. Like a rebel organism, our species discovered a colossal new source of energy, which had lain hidden and undisturbed for millions of years, and which no previous life-form had found a use for. It is the sheer rapidity in the rise of the waste from the exploited new energy source of buried carbon – largely in the form of gaseous carbon dioxide – plus the other combined wastes and environmentally transformative impacts that fossil fuels allowed humanity to achieve, that have now begun to overwhelm the self-regulatory capacity of the Earth system. This single element holds the key to a possible future mass extinction.

Flask world is now our world. Consider that our wastes are accumulating so fast in the oceans that no species can consume them; instead, massive dead zones are spreading around the world’s coasts, from China to the Gulf of Mexico, where the recent BP oil spill adds to the toll. We have produced novel organic chemicals and synthetic polymers that no microbes have yet learned to digest, and which are poisonous to most organisms – often including ourselves. And we are steadily eating our way through global biodiversity – from fish to frogs – consuming voraciously, and moving on to the next species when one is extinguished. Those species that are not edible we ignore and displace, whilst those that threaten or dare to compete with us we pursue mercilessly and annihilate. Thus is our rebel nature revealed.

There is a paradox however. Even as a putative rebel organism, humanity is a product of Darwinian evolution, like every other naturally generated life-form sharing our planet today. Moreover, we did not evolve the biological capacity to eat coal and drink oil – the energy from these abundant ‘nutrients’ is combusted outside the body rather than metabolised within it. Why us, then? Our mastery of fire was a product of the adaptability and innovativeness with which evolution had already equipped us long before, and that no other species had heretofore possessed. Humanity’s Great Leap Forward was not about evolution, but adaptation – and could therefore move a thousand times faster.

I don’t want to oversimplify: the Stone Age did not end in 1764 with James Watt’s invention of the steam engine. Clearly great leaps in human behaviour and organisation took place over preceding millennia with the advent of language, trade, agriculture, cities, writing and the myriad other innovations in production and communications that laid the foundations for humanity’s industrial emergence. But I would argue that the true Anthropocene probably did begin in the second half of the eighteenth century, for it was then that atmospheric carbon dioxide levels began their inexorable climb upwards, a rise that continues in accelerated form today. This date also marks the beginning of the large-scale production of other atmospheric pollutants and the planet-wide destabilisation of nutrient cycles that also characterise this new anthropogenic geological era.

Take population. When humans invented agriculture, some 10,000 years ago, the global human population was somewhere between 2 and 20 million³. There were still more baboons than people on the planet. By the time of the birth of Christ, the globe supported perhaps 300 million of us. By 1500, that population had increased to about 500 million – still a relatively slow growth rate. A global total of 700 million was reached in 1730. Then the boom began. By 1820 we numbered a billion. That total rose to 1.6 billion by 1900, and the growth rate continued to accelerate. By 1950 we were 2.5 billion strong, and by 1990 had doubled again to more than 5 billion. In 2000 the 6 billion mark was passed. At the time of writing, in late March 2011, we number an astonishing 6.88 billion individuals.⁴ Through the process of writing this book, another 225 million people were added to the total – just under half the entire world population of 500 years ago, now appearing in just three years.

But this still doesn’t answer the puzzle: Why us? And why were buried stores of carbon the ‘nutrients’ that allowed our species to proliferate so explosively? A satisfactory response requires a brief digression into the evolutionary origins of this remarkable hominid, for it is our past that holds the key to our present and future. This is the story of a species whose biological characteristics combined with an accident of fate to have world-shattering consequences. And it is a story that might shed some light on the central question of this book – whether we are rebel organisms destined to destroy the biosphere, or divine apes sent to manage it intelligently and so save it from ourselves.

Perhaps the environmentalist and futurist Stewart Brand put it best when he wrote these words: ‘We are as gods and have to get good at it.’⁵ Amen to that.

THE DESCENT OF MAN

Listening to some environmentalists talk, it is easy to get the feeling that humanity is somehow unnatural, a malign external force acting on the natural biosphere from the outside. They have it wrong. We are as natural as coral reefs or termites; our inherited physiology is entirely the product of selective pressures operating over millions of years within living systems. Our inner ear, for example, was once the jawbone of a reptilian ancestor. Babies in the womb begin life with tails, expressing in the earliest stages of life genes that illustrate our long evolutionary history. Our key biological characteristics – including those that have allowed us to emerge as ‘sapient’ beings – exist only because they conferred on our ancestors some selective advantage as they ate, fought, played and reproduced over millions of years within the natural biosphere.

The actual origin of life – how animate organisms assembled themselves out of inanimate chemicals without a Dr Venter to supervise affairs – remains a mystery. Perhaps the first self-replicating amino acids were formed in some primordial soup by a charge of lightning or a volcanic eruption. Or maybe, given the right environment and ingredients, life can spontaneously appear. Some suggest that extraterrestrial microbes may have hitched a lift onto the early Earth from passing meteors or comets. Either way, the first microbes appeared about 3.7 billion years ago, evolving into ‘eukaryotic’ cells – with a proper nucleus, cell walls and the capacity to metabolise energy – a billion and a half years later. These cells were probably made up of a symbiotic union of several bacteria, which is why mitochondria in our body cells today still have their own DNA. (Symbiosis, by the way, is quite as much part of the story of evolution as red-in-tooth-and-claw competition.)

Some of these early microbes, the cyanobacteria, learnt to use photons from the sun to split water and carbon dioxide in photosyn-thesis. They are probably Earth’s most successful organisms, for cyanobacteria are still prolific today. As eukaryotic cells learned to combine to form multicellular organisms, the stage was set for a major proliferation of life – though still only in the oceans – in an event dubbed the ‘Cambrian explosion’ by palaeontologists. During the Cambrian, from 540 million years ago, recognisable ancestors of many of today’s animal groups appeared. These include arthropods (insects, spiders and crustaceans), molluscs (snails, oysters, octopus), and even early vertebrates – the first fish. An evolutionary arms race kicked off, as predators evolved ways to catch, grip and swallow, whilst prey developed speed or armour to reduce their chances of being eaten.

Of all the technical novelties evolution called into existence, from scales to jaws, perhaps the most interesting is the development of sight. The eye may have been the innovation sparking this intense burst of Cambrian competition, for both predators and prey would have had an equally powerful reason to evolve vision. The fossil record demonstrates that sight evolved independently in different groups of animals, though in a remarkably similar way. The octopus, for example, has an eye much like ours, with a lens and a retina behind it, yet our common ancestor was probably some kind of sightless worm. All the higher animals that survived the Cambrian could see.

The oceans now had a fully developed food web, and it may have been to escape the marine killing fields that some of the less well-armoured fish first ventured onto land – already colonised, from about 450 million years ago, by plants and insects. Fins gradually morphed into limbs, though the hybrid water–land transition is still repeated in the life cycles of today’s amphibians, hundreds of millions of years later. As some of these early amphibians grew more accustomed to onshore life, they evolved into reptiles, with leathery skins to hold in moisture and eggs with watertight shells that could be laid on dry land rather than in ponds.

We are now up to 300 million years ago in geological time – nearly to the appearance of mammals, for our mammalian line is surprisingly ancient, if rather insignificant for most of its existence. The sail-back reptile Dimetrodon displayed many mammal-like features: its sail was probably a way to regulate temperature, perhaps demonstrating an early attempt at warm-bloodedness. Its teeth had differentiated into molars and canines, just as ours still do. Its descendants developed fur, modified – like the feathers of birds – out of reptilian scales, also as a way to control its body temperature. By the late Triassic, true mammals appeared, and were present on Earth throughout the entire age of the dinosaurs, though as very junior partners indeed. For the next 135 million years – during the entire Jurassic and Cretaceous periods – our ancestors stayed in the shadows, living furtive existences as the dinosaurs dominated the planet.

Mammals then were tiny, most no bigger than rats. They could dart out under the cover of darkness, snatching insects and worms as Tyrannosaurus slept. But there was an evolutionary tradeoff. Without the luxury of laying masses of eggs, and confined to burrows and crevices, mammals evolved sophisticated ways of nurturing their young: live births and lactation. Their specialised teeth enabled them to chew and grind up food, yielding more energy. In contrast the bulky dinosaurs wolfed their meals down whole. But the most outstanding adaptation of the mammals to their subordinate status was far more important than milk or molars. It was the evolution of intelligence. Contrary to popular myth, dinosaurs had big brains – not because they were smart, rather because they were big animals. But it is not brain size per se that counts for intelligence; more important are the relative proportions of brain and body, and in the diminutive mammals, this relationship was beginning to change. As one evolution textbook puts it: ‘The pint-sized mammal was the intellectual giant of its time.’⁶

So why did selective pressures force this shift? Most likely, the shadowy existence of mammals demanded very different skills from those of the daytime excursions of dinosaurs. The mammalian world was one of sound and smell as much as sight, demanding more subtle skills of deduction and reasoning. The smell of a predator, for instance, could mean danger if the killer is soon to return – or safety if it is gone. All would need to be kept in memory for retrieval later. Similarly, to interpret sound on a dark night would require consulting a mental map of some complexity, adding further evolutionary pressure for larger brains. The result was the neocortex, a completely new brain structure found only in mammals. This is our ‘grey matter’ – vital for all higher functions that we collectively define as ‘intelligence’, such as sensory perception, spatial reasoning and conscious thought.

The age of mammals dawned, with spectacular suddenness, 65 million years ago. Perhaps aggravated by extensive volcanic eruptions and consequent global warming, a mass extinction tore through the planetary biosphere when a large asteroid ploughed into the sea off modern-day Mexico. Once the dust had settled, the dinosaurs were gone – along with half of life on Earth. Why mammals made it through the bottleneck, no one knows. Perhaps they were better protected from the environmental holocaust thanks to their furry, furtive existences. Either way, the end-Cretaceous extinction cleared the way for the explosive evolution of mammals into all the ecological niches previously occupied by dinosaurs. Some took to the water, losing their four legs and re-evolving the fins they had lost over 300 million years earlier to become dolphins and whales. Others joined birds in the air, the fingers of their ‘hands’ splaying out to form wings, becoming bats. Still more returned to herbivory, and headed out into the grasslands now spreading through the continents, their bodies growing rapidly in size: these became bison, elephants, horses and other grazing and herding animals.

But our story follows a different group of mammals who struck out in a new direction. They headed off not into the land or out to sea but up the trees. Perhaps to escape predators on the forest floor, or to take advantage of succulent arboreal fruits, the lives of these ‘prosimians’, who appear in the fossil record about 55 million years ago, demanded a whole new set of skills. The paws of their ratlike ancestors evolved into gripping hands, more suited to a life spent grasping branches. Their requirement for smell declined. But their need for vision increased enormously, and not just any vision: their eyesight had to reveal excellent colour, and, most important, had to be front-of-head and stereoscopic to give depth perception.

The pressure was on for bigger brains. Mental calculations performed whilst speeding through the treetops had to be fast and accurate. Memory was once again useful, aiding decisions as to what types of trees could support what weight, how to grasp certain branches, or when to visit different fruiting bits of the forest. These were still small animals, but as they evolved better agility in the forest, their bodies grew larger. By 35 million years ago, true monkeys had appeared. By 22 million years ago, gibbons had split away from the evolutionary line. Orang-utans followed, at about 16 million years ago, and chimpanzees 6 million years ago. That left the hominids, and we are their only surviving descendants – all other hominid species, of which there have been a dozen at least, were destined to perish.

BIRTH OF THE FIRE-APE

Our lineage may be ancient, but modern Homo sapiens has been a very short-lived phenomenon, perhaps illustrating the biological anomaly that we are. Although bipedal hominids were stalking the African plains as long as 3 million years ago, true Homo sapiens – the evolutionary descendant of Australopithecus, Homo habilis and later Homo erectus – appeared less than 500,000 years ago, and perhaps as recently as 200,000 years ago.

Mitochondrial DNA passed through the maternal line suggests in fact that we are all descended from a single individual – the so-called Mitochondrial Eve – who lived in Africa 200,000 years ago. Further evidence comes from the remarkable homogeneity of human DNA: despite superficial differences in hair straightness, noses and skin colour, we are far more closely related than might be expected. (A single breeding group of chimpanzees will show more genetic variation than do all humans.⁷) This is strong evidence that modern humans did all descend from the same original group, and our dominance may have begun with a characteristic act of genocide, as the last Homo neanderthalensis survivors were ethnically cleansed from Europe and Asia by the new migrants. Since then, no other animal, whether on two legs or four, has challenged the dominance of Homo sapiens.

The most striking biological characteristic of the human ancestral line over the last few million years is the extraordinary progress of its brain development. Chimpanzee brains measure about 360 cubic centimetres in volume. Early Australopithecus had expanded its brain to about 500 cm³, whilst Homo erectus measured up with a brain size of about 800 to 900 cm³. Half a million years ago, the brain was expanding at an extraordinary rate of 150 cm³ every hundred thousand years.⁸ Modern humans typically have a brain size of 1,350 cm³, nearly four times the size of those of our nearest relatives, the chimpanzees.

One human innovation is often neglected in accounts of our evolution – and it may be one of the most important of all, because it allowed us to fuel our process of encephalisation (increased braininess). The brain is a very energy-hungry organ, consuming a quarter of all our energy use, as compared with 10 per cent in other primates and 5 per cent in most mammals.⁹ So how were the extra food requirements satisfied? Part of the answer is almost certainly the increasing amounts of animal protein in the human diet – hominid species quickly supplanted leopards as the dominant hunters on the African plains. But just as important was the advent of cooking, which enables food to be transformed into much softer and more calorific forms before being eaten. For over a million years humans have been eating cooked food, giving us a dietary advantage no animal has ever enjoyed before.

Cooking, of course, needs fire. Indeed there is a strong biological case for seeing humans as a co-evolved fire species. Fire made us physically what we are, by allowing us to grow vastly bigger brains through eating cooked food. The human gut is much smaller, and uses far less energy, than the digestive system of comparable animals. We also have weak jaws, small mouths and underdeveloped teeth compared with other primates. That first acquisition of fire acted as a powerful evolutionary driver, enabling humans to become the first truly sentient beings in history.

Fire, however, is a very special tool. Not for nothing is it identified in many human cultures as the preserve of the gods. Bonfires lit at the Celtic festival of Beltane symbolise the return of the sun to warm the Earth after the freezing nights of winter. In Navajo tradition, Coyote – who was a friend of humans – tricked two monsters on ‘fire mountain’ into letting him light a bundle of sticks tied to his tail, which he then took back to people. Perhaps the best-known fire tale of all is that of Prometheus, the Titan of the ancient Greeks (and son of Gaia, goddess of the Earth), who stole fire from the supreme god Zeus and brought it back to people. For this transgression he was punished by being chained to a rock and having his liver eaten out each day by an eagle.

And rightly so, for fire dramatically changed our relationship with the natural world. Acquiring the power of gods separated humans permanently and irretrievably from all other species. As well as cooked food, it afforded protection against predators and warmth on cold nights, allowing early humans to spread north out of Africa during the depths of the last ice age. Fire may have facilitated the spread of genes for hairlessness, as the need for body insulation diminished. However, once our hair was lost and our guts had shrunk, we were tied to the hearth – we could no longer exist without it.

No human can hope to survive in the wild today without fire, and this dependence marks a major qualitative shift in human relations with the biosphere. Other animals need only food. We are the only animal that has learned to harness an external energy source in a systematic way, through our reliance on fuel. It is this food–fuel relationship that most defines the fire-ape, Homo pyrophilus. Moreover, this innovation was perhaps the most important one in unbalancing our relationship with nature, for being armed with fire put the rest of the world at our mercy.

However, our dependence on fuel could also be a weakness. Once the forests were chopped down and the landscape denuded, humans might no longer be able to flourish. The story of the modern era, however, is the story of our transcendence over even this limitation. For modern humans were to discover a new source of fuel that would allow us to expand both our numbers and our dominance dramatically. This new fuel, in the form of underground deposits of fossilised biological carbon, was to be the energy springboard that catapulted our species – and the planet – into an entirely new geological era, the Anthropocene. Using the tool of the gods, we were to become as gods. But unlike Zeus, we still live in ignorance about our true power. And time is running out, for the flames of our human inferno have begun to consume the whole world.

Chapter Two

The Biodiversity Boundary

Our fire-sticks and engines have turned humans into extremely successful predators. We have poisoned, outcompeted or simply eaten so many other species that the Earth is currently in the throes of its most severe mass extinction event for 65 million years, and it is this crisis of biodiversity loss that arguably forms humanity’s most urgent and critical environmental challenge. Many of our other impacts on the Earth system are more or less reversible, but extinction is for ever, and a flourishing diversity of life is essential for the biosphere to function successfully during the Anthropocene and beyond. By removing species, we damage ecosystems, collapse food webs and ultimately undermine the planetary life-support system on which our species depends just as much as any other.

The planetary boundaries expert group proposes a biodiversity loss boundary of a maximum of ten species lost to life per million species per year. The current rate of loss is already one or two orders of magnitude greater than this: conservationists estimate that 100 to 1000 species per million are currently wiped out annually. Meeting this boundary target is possible, but to do so will require a massive increase in the global attention and funding given to the issue and to solving it. We must create many more nature reserves, both on land and at sea. We must properly fund conservation, to defeat poachers and protect wildlife from direct threats. Above all we must alter our accounting systems so that living systems – from rainforests to polar tundra – are given the value they deserve as literally priceless assets of natural capital. This means using the power of markets, with most payments for biodiversity protection going to the local people who are always the best custodians of their local environment.

If we are to save what remains of the glorious diversity of life on Earth, we will have to act fast. A quarter of the world’s mammals, a third of amphibians, about 13 per cent of birds, a quarter of warm-water corals, and a quarter of freshwater fishes are globally threatened with extinction. The rate of loss is accelerating, despite increasing concern about this brutal devastation of our planet’s natural history: whilst 36 mammals improved in terms of how threatened they were between the 2007 and 2008 Red Lists, 150 saw a deterioration, from vulnerable to endangered, from endangered to critically endangered, or critically endangered to extinct.¹

In 2002 world governments agreed a target ‘to achieve by 2010 a significant reduction of the current rate of biodiversity loss at the global, regional and national level as a contribution to poverty alleviation and to the benefit of all life on Earth’. Laudable, of course. So was it met? Not even close. To put numbers on the current crisis, a recent report in Science looked at 31 different indicators – things like habitat quality, population trends, extinction risk and so on – and found that virtually all of them were either getting worse or showed no improvement in the last decade.² Stalin said that the death of one person was a tragedy, the death of millions a statistic (and he was an expert). So it seems for species too. Each story is a unique tragedy, yet the aggregated numbers somehow fail to convey the magnitude of this loss.

Even where absolute extinction has been avoided, many species have become functionally extinct in the sense that their remaining numbers are so few – or so scattered – that they no longer play any effective part in the ecosystem. The Iberian lynx, for example, is not extinct – not yet – in the wild, but its total population (between 84 and 143 adults; split into two isolated populations in Spain) is so tiny that it can hardly still be considered the apex predator it once was. (The lynx may be completely extinct in neighbouring Portugal: its survival has been inferred only by the discovery of a single dropping, identified by molecular analysis in 2001.³) Globally the abundance of vertebrate species fell by nearly a third between 1970 and 2006, according to the 2010 Global Biodiversity Outlook.⁴ Forget about extinctions: there are now a third fewer wild animals in total on the planet than there were forty years ago. That really is a shocking figure.

Even emblematic species like the tiger have their backs to the wall. Globally, only about 3,500 wild tigers remain – an extraordinary statistic given the charisma and recognition factor of this species, whose form has been emblazoned on everything from cereal packets to petrol stations. Three subspecies, the Bali, Caspian and Javan tigers, are already extinct; the South China tiger has probably joined them, for no one has seen it in the wild for 25 years.⁵ According to a late-2010 study, the decline in tiger numbers ‘has continued unabated’ for the last two decades: only 1,000 breeding females now survive, over less than 7 per cent of their historical range. Several Indian so-called ‘tiger reserves’ no longer have any tigers in them at all. Yet saving the tiger could cost as little as $82 million per year, according to one estimate – this is all it would take to protect the remaining 42 sites around Asia where viable tiger populations remain.⁶ All that is needed is a mechanism to raise the funds and an implementation plan to safeguard the reserves.

Particularly badly hit by our success have been our nearest relatives, the great apes. All are threatened with extinction in the wild. In Asia the orang-utan – once common from South China to the Himalayas – is now reduced to a remnant of between 45,000 and 69,000 individuals, mostly in the sort of lowland forests in Borneo that seem to be particularly irresistible to oil-palm plantation owners. In Africa the famous ‘gorillas in the mist’ of Virunga National Park in the Congo are down to about 380 individuals, under siege by marauding rebels as well as by poachers and bushmeat hunters. To put humans in our proper context, try entering ‘great apes’ into a www.iucnredlist.org (a website run by the International Union for the Conservation of Nature, featuring its Red List of endangered species) search. When I tried, the results were as follows:

Gorilla beringei (Eastern Gorilla) – Status: Endangered, Pop. trend: decreasing.

Gorilla gorilla (Lowland Gorilla) – Status: Critically Endangered, Pop. trend: decreasing.

Homo sapiens (Human) – Status: Least Concern, Pop. trend: increasing.

Pan paniscus (Gracile Chimpanzee) – Status: Endangered, Pop. trend: decreasing.

Pan troglodytes (Common Chimpanzee) – Status: Endangered, Pop. trend: decreasing.

Pongo abelii (Sumatran Orang-utan) – Status: Critically Endangered, Pop. trend: decreasing

Pongo pygmaeus (Bornean Orang-utan) – Status: Endangered, Pop. trend: decreasing

As this list shows, we are just apes. But with our newfound global power comes a responsibility for proper global stewardship. This is a new task for humans to take on, certainly at a planetary level. But the time for this shift is long overdue, for a brief review of our history to date shows us in a very singular role: that of serial killers.

THE PLEISTOCENE OVERKILL

Many thousands of years ago a dramatic ecological calamity began to sweep through the fauna that inhabited the Earth’s disparate continents. Australia lost most of its large animals first, about 46,000 years ago. North and South America saw a similar extinction wave 13,000 years ago. New Zealand, meanwhile, kept hold of its big-bodied animals until a mere 700 years ago. What happened at each of these points in time? Did the climate perhaps change, leaving large animals stranded? Unlikely: there is no correlation between global climate change and the various extinction pulses. Did a meteor strike or a volcano blow? Again, there is no way to pin all of these different calamities, taking place at very different times, on a single geological event. Indeed, the true nature of this extinction calamity is much more familiar. It came on two legs, for a start. What links these points in time is simple: they mark the moment when humans arrived.

Modern humans have at least dealt out death fairly: we began our existence by killing each other. In what looks like a prehistoric bout of all-too-modern ethnic cleansing, Homo sapiens probably drove its closest hominid relatives, Homo neanderthalensis and Homo erectus, to oblivion. A minority of archaeologists cling to the notion that some interbreeding must have taken place, but genetic studies show this is unlikely.⁷ Modern human DNA instead confirms that all of us are descended from the same small initial Homo sapiens population that migrated out of Africa 50,000 years ago.⁸ The last Neanderthals hung on in remote mountainous parts of France until 38,000 years ago, and in southern Spain until about 30,000 years ago. The very last families died a few thousand years later in Gorham’s Cave in what is now Gibraltar, when their final refuge on the extreme southern edge of the continent was overrun.⁹ Officially, the direct cause of their ultimate demise is a mystery, but I think we can guess who the culprit was.

There is certainly enough evidence to mark out a crime scene. One Neanderthal skeleton discovered in Iraq bears a peculiar puncture wound on one of its ribs – a mortal injury that is most consistent with a spear thrown by an anatomically modern Homo sapiens.¹⁰ In early 2009, the anthropologist Fernando Rozzi reported the discovery of a Neanderthal child’s jawbone, found together with anatomically modern human remains at the cave of Les Rois in southwestern France.¹¹ The bone bore characteristic cut marks, similar to those found on butchered reindeer skulls, suggesting that the tongue had been cut out and eaten. Some loose teeth scattered around also had holes drilled in them, perhaps as parts of a morbid ceremonial necklace. Rozzi drew an unequivocal conclusion: ‘Neanderthals met a violent end at our hands, and in some cases we ate them,’ he said.¹²

There is even stronger evidence surrounding who killed most of the world’s largest animals, for their butchered bones are found stacked up everywhere humans invaded. As palaeontologist Richard Cowen writes in The History of Life, ‘From Russia to France, [archaeo-logical] sites contain the remains of thousands of horses and hundreds of woolly mammoths.’¹³ But the slaughter was far worse in the New World, where native species had no previous experience of this naked and harmless-looking but surprisingly rapacious two-legged predator. The North American death toll included six species of ground sloths, two species of mammoths, all mastodons, a giant bison, seven species of deer, moose and antelope, three species of tapirs, the North American lion, the dire wolf, the giant anteater, the giant turtle, the giant condor, all ten species of North American horses (then absent until reintroduced by invading sixteenth-century Europeans), two species of sabre-toothed cats, eight species of cattle and goats, the North American cheetah, four species of camels and two species of large bears.

But the biggest wipe-out of all took place in Australia, which saw a near-total extinction of large wild animals. The continent lost some extraordinary creatures: a gigantic horned turtle as big as a car, enormous flightless birds standing more than 2 metres tall and weighing half a tonne, a snake 6 metres long, and a giant predatory lizard that grew up to 7 metres in length and must have been the most fearsome reptilian predator since the dinosaurs. About twenty species of large marsupial disappeared, including a cow-sized wombat and a kangaroo 3 metres high. Quite how and when they died remains controversial: many archaeologists have tried to absolve Homo sapiens of the crime, pointing to the lack of kill sites and the low density of human population. But the extinction is roughly coincident with human arrival in the continent, and the pattern – affecting the largest species disproportionately – is exactly the same as everywhere else.

Further damning evidence comes from Tasmania, which retained its giant kangaroos (and various other megafauna) for four thousand more years, until falling sea levels allowed humans to finally invade – whereupon the island’s giant kangaroos (amongst six other large-bodied species) promptly died out.¹⁴ Any remaining doubters need only look to New Zealand. When Polynesian people first arrived by boat a mere 700 years ago, they found a unique island ecosystem where – thanks to millions of years of geographical isolation – birds rather than mammals or reptiles had evolved to become the dominant land animals. Giant flightless moas stalked the forests, whilst enormous eagles, the largest ever known, with wingspans of the order of 3 metres, soared above the mountains. Within as little as a century all – along with half of the islands’ other terrestrial vertebrates – were dead.¹⁵ This time there can be no dispute as to the cause of death or the identity of the killers, for Maori dwelling sites are surrounded by piles of moa bones – some so extensive that they have since been quarried for fertiliser. No doubt believing that the abundance of their moas would last for ever (another pattern that keeps repeating itself), the Maoris wastefully ate only the upper legs and threw the rest away.¹⁶

Only one continent’s large animals survived relatively unscathed. That continent was Africa, whose megafaunal inhabitants had co-evolved with hominids over millions of years and had therefore acquired a great deal of useful experience about living with Homo sapiens. As a result, Africa gives us the best idea of what a pre-human landscape might have looked like, with big animals like elephants browsing the undergrowth and herds of wild horses and cattle stirring up dust clouds across the savannah. Indeed, African ecosystems have been used as a model for proponents of ‘rewilding’ parts of North America; if cheetahs, elephants and camels can be imported into places like Montana, perhaps they could assume the ecological niches vacated by their extinct relatives, some have suggested.¹⁷ This is a romantic but vain hope, not least because the ancient homeland of these large surviving animals is seriously endangered by today’s generations of human beings. Africa is safe no more.

Right across the world, these lost big animals left ‘ghost habitats’ behind – trees that still bear specialised fruits hoping some long-gone giant will distribute them, or thorny bushes protecting themselves against browsing by extinct large herbivores. In Brazil, more than 100 tree species still produce obsolete ‘megafauna fruit’, evolved for dispersal by extinct elephant-like creatures called gomphotheres. Not surprisingly, with no living animals to disperse their seeds, these trees are now themselves becoming endangered. In Madagascar many plants grow thin zig-zag branches to protect themselves from leaf-munching elephant birds, another giant flightless bird that became a casualty of Homo sapiens – and that laid eggs so large it is thought to have inspired the legend of the roc in Sinbad the Sailor. Modern-day Siberia’s wet peaty tundra may stem from the loss of the mammoths, whose earlier grazing nourished a much more productive dry steppe-type biome before their extinction at human hands a mere 2,000 years ago.¹⁸ In Africa elephants play a key role in opening up forests by pushing over trees – a function their relatives in the Americas would also have served before being wiped out by man. In all cases, the vanished megafauna maintained a more diverse ecosystem than the simplified one that replaced them after their sudden demise.

All told, the Quaternary Megafaunal Extinction between 50,000 and 3,000 years ago carried off about a half of the world’s large animals (including 178 species of large mammals). This was an extinction wave that bears comparison with the largest in the geological record – but it is still only a prelude to what was to come. The wipe-out that accompanied human migration across the continents was restricted only to the most large-bodied and easily targeted species. In comparison, today not only are the largest animals still at risk, but also small amphibians, songbirds, flowering plants, insects and much else besides. The Sixth Mass Extinction, or the Anthropocene Mass Extinction, is already well advanced – and the death toll will soon rival that at the end of the Cretaceous, when the dinosaurs (and half of the rest of life on Earth) disappeared. Today the small as well as the large wait in line for the cull.

THE SAD STORY OF THE SEA

Perhaps the ecosystem that has been most depleted of its animals in the modern era is the least visible one: the sea. Whilst disappearances on land are comparatively easily studied and recorded, what goes on beneath the waves is an enduring mystery, and humans have traditionally – and tragically – viewed the sea’s bounty as limitless. History once again provides a cautionary tale: the whaling industry, for example, managed to reduce cetacean populations once in the hundreds of millions to near-extinction in just a couple of centuries. The sheer scale of the effort was enormous: in the mid-nineteenth century, when many Atlantic whale species had already been exterminated, some 650 whaling ships operated in the Pacific, employing 13,500 seamen.¹⁹ Southern right whales saw their population reduced to as few as 25 breeding females by 1925,²⁰ after nearly two centuries of devastating slaughter: a low-end estimate is that 150,000 were killed between 1770 and 1900.

Today the eastern North Atlantic right whales are marked as ‘critically endangered, possibly extinct’ on the IUCN Red List, whilst in the western Atlantic a population of about 300 individuals qualifies merely for ‘endangered’ status.²¹ Several are still killed each year by collisions with ships and through entanglement in fishing nets. As each species was destroyed in turn in its primary areas, the industry moved further afield, killing whales from Antarctica to the Galapagos Islands. Calving grounds were often targeted: congregating mothers could be killed while at their most vulnerable and calves captured too or left to starve. Each population was exploited to near-extinction. Most whales are slow-breeding, and with reproduction rates of 1–3 per cent per year the economically rational whaler would gain more benefit from driving the species to extinction and investing the profits elsewhere (to accumulate interest at perhaps 5 per cent a year) than leaving any alive in the sea.²² Such is the remorseless logic governing the unregulated capitalist exploitation of nature.

As technology improved, so the slaughter worsened. Steam ships could pursue and kill the fastest species, whilst factory ships could process carcasses at sea without having to call at a port. One after the other, blue, sei, fin, humpback, sperm and minke whales were wiped out over most of the ocean. New whaling grounds would be exhausted at most after a decade, sometimes from one year to the next. All told, the twentieth century saw the slaughter of about 3 million whales, leaving only between 10,000 and 25,000 blue whales in the whole world. The killing goes on still, thanks to the ‘scientific whaling’ loophole (more like a chasm) in the current International Whaling Commission (IWC) system. Norway, Iceland and Japan continue to kill whales today using the fig-leaf of scientific research, and these countries and their allies have recently tried to overturn the whaling moratorium altogether at the IWC. Whilst it is plausible that stocks of smaller whales like minkes can support a sustainable annual catch, there is a stronger case for leaving the whales alone altogether until their numbers – and the marine ecosystem generally – can properly recover.

Although no whale species were driven to outright extinction, some marine animals have been extinguished completely. The Steller’s sea cow, a gentle and intensely social Pacific species, was wiped out for its meat and blubber in the mid-eighteenth century. The great auk – a flightless penguin-like seabird that once lived in huge numbers around the North Atlantic – was also exterminated in a determined campaign of slaughter. Once clubbed to death, the bodies would be plunged into boiling water, their feathers torn out (for stuffing pillows and mattresses, as well as adorning hats), whilst the carcass would be boiled for its oil (used for lighting lamps) and the remainder used to fuel the fires that powered the whole ghastly enterprise.²³ Ship crews would move onto remote islands with the sole purpose of killing as many birds as possible during the summer months. Even on the brink of extinction, the hunting continued: the last breeding pair of great auks were beaten to death in Iceland on 3 June 1844, and their single remaining egg was broken.²⁴

Early seafarers were not exactly sentimental about the creatures they encountered. William Dampier, writing about the fur seals he saw on Juan Fernandez island in 1709, marvelled at their beauty, agility and grace, ‘how they lie at the top of the water playing and sunning themselves’ as he put it. But like everyone, Dampier soon got down to business. ‘A blow on the nose soon kills them,’ he added helpfully. ‘Large ships might here load themselves with seal-skins and Trane-oyl [oil]; for they are extraordinary fat.’²⁵ And large ships did just that, reducing the island’s enormous colonies of seals down to an eventual grand total of just two hundred individuals. One American naval captain related in 1891 how the shooting of fur seal females at sea left their offspring on the shore to starve: ‘Thousands of dead and dying pups were scattered over the rookeries, while the shorelines were lined with emaciated, hungry little fellows, with their eyes turned towards the sea uttering plaintive cries for their mothers, which were destined never to return.’²⁶

Species after species was relentlessly pursued. Walruses were boiled down for their oil. Giant tortoises were seized in raids on the Galapagos Islands and kept alive by being turned on their backs in ships’ holds for months at a time before being eaten for their meat. In ‘one of the great wildlife exterminations of colonial times’, as marine historian Callum Roberts puts it, an original population of 50–100 million hawksbill turtles in the Caribbean was reduced to just a few thousand (it is still critically endangered worldwide).²⁷ Sea otters, which once swam in their millions in Pacific coastal waters from Mexico to the Arctic, were reduced to fewer than two thousand by 1911. As industrialisation proceeded, the depletion of whole areas could speed up: when seal colonies were first discovered in the remote South Shetland islands in 1820, a quarter of a million were killed and the population brought to near-extinction within just three years.²⁸

All this is in the past, of course. But its impacts are still very much with us, and in many different ways the global slaughter continues. There are no large wild animals left on our planet in anything like the abundance they once enjoyed. Those few hunted species that remain are still under intense pressure; it is as if humanity has learned nothing from past exterminations. Today the extinction of the bluefin tuna is an imminent threat: quotas set at the time of writing by the sadly misnamed International Commission for the Conservation of Atlantic Tunas are high enough to permit fishing boats to catch every single adult bluefin during next year’s season.²⁹ The fish don’t have much of a sporting chance: illegal spotter planes guide industrial fleets to wherever the last few thousand individuals can be found.³⁰ Nor have the economics changed much since the days of whaling: the trading conglomerate Mitsubishi was recently accused of stockpiling frozen bluefin in expectation of a post-extinction price bonanza.³¹ With individual fish worth up to $100,000 on the Tokyo sushi market, the tragedy of the commons plays out anew every time the tuna fleets set sail.

The destruction of fish habitat is also routinely ignored in the interests of short-term profit. The North Sea off England’s east coast, for example, was not always the murky and uninviting body of water it is today: once its waters were kept clean and sediment-free by rich oyster beds on the sea floor – but these have been ploughed up by trawlers and the sea bottom reduced to a muddy, turgid wasteland. The pressure is unrelenting: intensively fished areas can be hit tens of times in a single year. Deep cold-water corals thousands of years old, supporting flourishing colonies of other marine life, can be reduced to rubble by a single pass of a trawler. Photographs of trawled coral colonies show piles of stony wreckage like the ruins of a pillaged city.

Oceanic island birds are some of the most threatened species anywhere because they are particularly vulnerable to predation by introduced alien invaders. Half of Hawaii’s 140 native bird species are now extinct, thanks to the devastation wrought by introduced rats, pigs and cats. On Australia’s Christmas Island, the Pipistrelle bat population (I realise bats are mammals, but the point is the same) has plummeted by 90 per cent in the last decade (down to a mere 250 mature individuals), due largely to predation by invasive species like wolf snakes, rats and feral cats.

Consequently, one of the quickest wins for biodiversity conservation is the elimination of alien species from islands. In the biodiversity ‘hotspot’ of the Galapagos Islands, 140,000 marauding goats have been removed, whilst in the islands off western Mexico – well-known for their unique species and thriving seabird colonies – cats, rats, goats, pigs, donkeys and rabbits have all been removed to protect endemic animals and plants from destruction. The cost has been tiny, compared with the benefits achieved: just $20,000 per colony for 200 seabird colonies protected, and $50,000 per species for 88 endemic species that are found nowhere else on Earth.³² That any species anywhere else might be lost for the want of such paltry sums would be a terrible indictment of our current lack of concern for the myriad of plants and animals that share this planet with us.

BIODIVERSITY AND THE EARTH SYSTEM

Of course, we may fret about biodiversity loss, but life in general is incredibly resilient. Living species have colonised every nook and cranny of the planetary system. Spiders, anchored by tiny threads, whizz across the stratosphere carried by hundred-mile-an-hour jet-stream blasts. Thermophilic bacteria cluster hungrily around deep-sea volcanic fissures where temperatures soar well past boiling point. Oil-well samples show flourishing microbial life 2 kilometres or more below our feet.³³

Extraordinary diversity is everywhere: a single 30 g sample of soil from a Norwegian forest has been estimated to contain 20,000 different species of bacteria.³⁴ We are ourselves walking ecosystems: tiny mites crawl around in our eyelashes, whilst billions of bacteria populate our guts. Higher forms of life may be fewer in number, but are far more varied in form. All told, there are estimated to be 11 million species in the world – with countless more waiting to be discovered. Scientists working on a 2009 update for a global biodiversity report first issued in 2006 had to add 48 new reptiles, 200 new fish and 1,184 flowering plants, all identified for the first time in the intervening three years.³⁵ Recently ecologists working in the crater of a single extinct Papua New Guinean volcano found 16 new frogs, three new fish, a giant bat and giant rat; luckily a BBC camera crew was on hand to record each unique moment of discovery.³⁶

But who cares anyway? Here’s Marcel Berlins, columnist on the Guardian: ‘I passionately believe in saving the whale, the tiger, the orang-utan, the sea turtle and many other specifically identified species. What I do not accept is the general principle that all species alive today should carry on existing forever. We have become so attuned to treating every diminution of animals, insects, birds or fish with concern that we have forgotten to explain why we think it so terrible.’ Warming to his argument, Berlins concludes: ‘How many mammal species can you think of? Can the remainder be that important? Can their loss matter that much, to you or to the world? Of course we must fight hard to retain as many species as we can; but it isn’t a tragedy if we lose quite a few along the way.’

Berlins’s common-sense argument is a reasonable one, and its answer not as obvious as one might expect. After all, the biosphere has lost woolly mammoths, Tasmanian tigers and countless other charismatic species already, and yet the world goes on turning. Environments we previously assumed were pristine, like the Amazonian rainforest or the Siberian tundra, now turn out to be more of a product of human engineering than we once thought – and their vanished mega-fauna have left little identifiable trace, and certainly not one that affects our current lives from day to day. Indeed, most people are unaware that the Quaternary Megafaunal Extinction even happened, and view the disappearance of the mammoth as an interesting but still unsolved mystery, if they think about it at all. Does it really matter if the thinning-out process accelerates a little more?

There are some good utilitarian arguments to show why destroying biodiversity is not a good idea. The biologist E. O. Wilson tells a story of how a small tree in a remote swamp forest in Borneo yielded an effective drug against HIV – except that when collectors returned to the same spot a second time they found the tree had been cut down, and no more could be found.³⁷ (Happily for AIDS sufferers, a few remaining specimens were eventually located in the Singapore Botanic Garden.) Who knows which tangled Amazonian vine might one day deliver a cure for cancer? But this is only part of the story, for it is ecosystems in their entirety that are valuable and irreplaceable as much as the individual species they contain. Biodiversity loss is a planetary boundary of the utmost importance not because killing off species is morally wrong, but because a healthy diversity of living organisms is essential for ecosystems to function properly.

Living systems keep the air breathable and water drinkable for themselves and us, but to continue to perform these vital services they need to retain their complexity, diversity and resilience. Once humans start to pick off component parts, an ecosystem may appear to function as normal for a while – until some unpredictable tipping point is reached, and collapse occurs. Conceptually this is a bit like the game of Jenga, where wooden blocks are built together in a tower and pieces removed from underneath one by one by each player. Needless to say, whoever removes the crucial ‘keystone’ piece that topples the tower loses. The lesson of Jenga is an important one, because it shows that there is no single keystone: each removed block makes the tower less and less stable, but no one knows in advance which piece will lead the tower to collapse.

Keystone predators are particularly important to ecosystems. In the marine realm, great sharks – like tiger, hammerhead, bull and thresher sharks – have in recent years been mercilessly targeted worldwide: their numbers have plunged by up to 99.99 per cent in some seas.³⁸ On the eastern North American coast, rays are no longer being eaten by the vanished sharks, and have increased their numbers as a result. They in turn eat scallops and oysters, destroying the formerly productive scallop fishery.³⁹ The process is known as a ‘trophic cascade’ and is now understood to be a fundamental part of ecological dynamics. An ecosystem shift can be irreversible: the Newfoundland cod, whose numbers collapsed because of overfishing in 1992, are unlikely ever to return in substancial numbers. Cod larvae are eaten by smaller fish and crustaceans like lobsters (once kept in check by more numerous adult cod), which dominate the ecosystem instead.⁴⁰

For land-based ecosystems apex predators are just as important. In Yellowstone, the reintroduction of wolves in 1995 has allowed the regrowth of native aspen trees for the first time in half a century. This is because elk populations are now being controlled by wolf predation, preventing overgrazing and allowing trees to recover.⁴¹ In nearby Grand Teton National Park in Wyoming small birds like the gray catbird and MacGillivray’s warblers may depend for their survival on wolves, recently reintroduced to the area after an absence of 75 years. Both birds flourish in riverside willows: but the willows, like Yellowstone’s aspens, were being overgrazed by hungry moose. In places where predators are still absent, expensive management schemes have to artificially keep down the populations of deer and other grazing herbivores – a service that wolves perform for free.

However, it is not only predators that count. Bottom-up interference can also dramatically destabilise an ecosystem. In the early 1980s a new pathogen appeared in the Caribbean near the mouth of the Panama Canal, wiping out sea urchin populations with extraordinary virulence: within a year 98 per cent of the urchin population was gone, in what is still the worst recorded die-off of any marine animal in history. Because urchins are herbivorous grazers they perform an important function on reefs, keeping the corals clear of algae and seaweed that would otherwise choke the reef systems. Without them, the corals lacked protection, and within a year reefs from Jamaica to the coast of Venezuela disappeared under a thick layer of green slime.⁴² After a decade, just 5–10 per cent of the original coral cover was left,⁴³ and little more remains to this day.⁴⁴ A whole marine ecosystem had irreversibly collapsed because of the removal of one of its key components.

Functioning ecosystems need not just a varied number of species, but also – just as crucially – habitat. Humans have disturbed, fragmented or ploughed up huge areas of the planet’s terrestrial surface. But there is a direct correlation between biodiversity and land area: the smaller the remaining fragment, the fewer species it can support. This so-called ‘species–area relationship’ was illustrated by a massive – though unintentional – field experiment beginning in 1986, when a gigantic hydroelectric dam was built in the jungles of Venezuela. When the lake behind the dam began to fill, the rising tide turned a hilly area of four thousand square kilometres into isolated islands, each with its tropical forest plant and animal species cut off by the surrounding waters. Some of the new islands were very small, just an acre or two in size, whilst others were relatively large, with areas of 150 hectares or more. As you might expect, the smallest islands lost the most biodiversity – three quarters of their original complement – due to their small areas. All islands, large and small, lost their top predators: the jaguar, puma and harpy eagle. But the species that did survive quickly became more abundant as both competition for food and predation ceased abruptly. Some islands were overrun by leaf-cutting ants. One, having housed a large herd of capybaras as the waters rose, ended up as little more than bare ground covered by capybara dung. On some islands, monkeys decimated bird populations, whilst on others rodent populations increased 35-fold.⁴⁵ In all cases, complex and formerly diverse ecosystems were torn apart and thrown into chaos.

From these and many other examples, ecologists now understand a fundamental principle of biodiversity: that the greater the diversity of species, the more resilient and stable an ecosystem can be. The same, of course, applies to the biosphere as a whole. We are only just beginning to realise all the myriad ways that different species act unconsciously together to keep this planet habitable and its climate tolerable. Might there be some kind of global ‘tipping point’ – like the ones that were passed in the Newfoundland cod fishery and the Caribbean coral reefs – where some kind of irreversible global ecosystem shift takes place? This is the possibility that the planetary boundary on biodiversity is intended to prevent: it is now absolutely clear that the Earth’s living biosphere depends fundamentally on the maintenance of a broad level of species diversity. If the Sixth Mass Extinction is allowed to continue – or still worse, accelerate further – then the chance of a global-scale ecosystem collapse can only continue to grow. the price of pandas

The current crisis in biodiversity tells us loud and clear that conventional approaches to conservation have failed. ‘Paper parks’ – named but barely protected – in developing countries are routinely violated by poachers and loggers. What areas are set aside for nature reserves are too small and too fragmented. At sea fishermen compete with each other in a global race to the bottom, knowing that if they do not catch the last bluefin tuna, someone else will. No wonder the 2010 Global Biodiversity Outlook report is full of ominous words and phrases like ‘serious declines’, ‘extensive fragmentation and degradation’, ‘overexploitation’ and ‘dangerous impacts’. To meet the planetary boundary, we need to make urgent changes in policy.

Biodiversity loss is fundamentally an enormous market failure, because the people that profit from destroying biodiversity are not generally the same people who lose out when the rainforests, mangroves and coral reefs are finally gone. When palm-oil companies move into the last remnants of rainforest in Borneo, the biofuels they sell deliver benefits to shareholders and foreign consumers, but local people are the losers, as are all the rest of us because of the destructive impact on the world’s climate and ecosystems. Our chief task today is to design systems that value nature in a direct and marketable sense and deliver hard cash to those who are in a position to protect ecosystems in a reasonably intact state. What is needed is not more moralising, but more money.

This kind of talk makes many environmentalists queasy. Greens generally view biodiversity conservation as a moral cause, and any discussion of financial mechanisms and marketing schemes arouses strong and principled opposition. Why should any other species, each with just as much right to occupy this living Earth as us, be forced to ‘pay its way’? This objection is understandable but wrong-headed: what I am proposing is not a liquidation of nature to make money, but using money simply as a convenient means to safeguard its protection. Money is a measure of value: put a price on wild animals and plants and we will put a value on them too. This is a pragmatic strategy, only to be used in desperation because the others have failed.

But how can the value of natural systems be quantified, let alone brought into the market? A possible approach is to try to assign an imputed shadow price to the ecosystem services – fresh water, clean air, recreational benefits and so on – that different habitats deliver. One study suggests a value of $200,700 per square kilometre for ‘high-biodiversity wilderness areas’, whilst another finds that ‘endemic bird areas’ might be worth $88,710 per square kilometre.⁴⁶ The imputed value of coral reefs – as destinations for tourism, nurseries for commercially valuable fish and shoreline protectors against storms, for example – has ranged from $100,000 to $600,000 per square kilometre.⁴⁷ The values of individual species have also been quantified, based on estimates from public surveys of ‘willingness to pay’ to prevent their elimination. Using this methodology (and in 2005 US dollars) the Eurasian red squirrel is worth $2.87; the California sea otter $36.76; the giant panda $13.81; the Mediterranean monk seal (almost extinct): $17.54; the blue whale: $44.57; the brown hare: $0.00; the Asian elephant: $1.94; the Northern spotted owl: $59.43; and the loggerhead sea turtle: $16.98.⁴⁸

One team of scientists, led by Robert Costanza – a member of the planetary boundaries expert group – even went so far as to publish an aggregate monetary value of the whole biosphere. There is a conceptual flaw in this, as many have pointed out, because the human economy is a subset of the natural biosphere and could not in any conceivable way replace it. As one environmental scientist sniffed: when it comes to pricing the biosphere as a whole, ‘there is little that can usefully be done with a serious underestimate of infinity.’⁴⁹ Even so, Costanza and colleagues came up with a precise figure for ‘the total economic value of the planet’ of $33 trillion per year (as compared with a total global GNP of, when the paper was written in 1997, $18 trillion).⁵⁰

The problem with these figures however is not that they are too precise but that they are not real. No one pays anyone else $33 trillion a year to protect the planet from destruction, nor are any of us actually forking out $17.54 to keep Mediterranean monk seals from going extinct. Yet in a globalised capitalist economy actual, real-world revenue flows are essential if they are to compete with the commercial drive that is destroying and displacing the remaining bits of natural ecosystem worldwide. Mangroves may be valuable as protection against storms and shelter for fish, but someone needs to be paid to look after them if they are not to be chopped down to make way for lucrative shrimp farms. In other words, a financial constituency needs to be created that has a vested interest in protecting its assets – assets that are, in this case, natural rather than commercial capital.

The starting point for this process has to be valuing natural capital. As Pavan Sukhdev, lead author of the 2010 The Economics of Ecosystems & Biodiversity (TEEB) report, is fond of saying: ‘You cannot manage what you do not measure.’ One of the report’s key recommendations is that the present system of national accounts should be ‘rapidly upgraded to include the value of changes in natural capital stocks and ecosystem service flows’. The TEEB report consciously encourages the use of banking and accounting terminology with regard to biodiversity: its authors have launched a ‘Bank of Natural Capital’ website to encourage wider awareness of the ideas it raises. This even extends to proposing an ‘internal rate of return’ for ecosystems, which varies from 40 per cent for woodlands to 50 per cent for tropical forests to 79 per cent for better-managed grasslands.⁵¹ ‘The flows of ecosystem services can be seen as the “dividend” that society receives from natural capital,’ the TEEB Synthesis Report suggests.⁵²

If this all sounds rather capitalistic, it is worth noting that the biggest losers from the current largely unregulated and unquantified degradation of natural capital are the world’s poor. The TEEB report stresses that forests and other natural ecosystems make an enormous contribution to the so-called ‘GDP of the poor’ (up to 90 per cent) and that conservation efforts can therefore directly contribute to poverty reduction. In contrast, one estimate of the ‘environmental externalities’ (the off-balance sheet costs offloaded onto the environment) of the world’s top 3,000 listed companies totals around $2.2 trillion annually.⁵³ All of this value is going into the pockets of corporate shareholders, where it is unlikely to benefit the poor. Moreover, insisting that natural systems are priceless, as many campaigners do, is in practice akin to setting their effective price at zero. The language and practices of economics may offer the strongest tools today for use in nature conservation.

But these imputed values need to be translated into real monetary worth if the natural assets that generate them are to be properly protected. One of the most promising ways of doing this is known as ‘payments for ecosystem services’ – designing revenue streams that go to communities and landowners who need to be persuaded to keep wetlands and forests intact. In Mexico the annual rate of deforestation has been halved since a 2003 law allowed a portion of water charges to be paid out to landowners willing to preserve forest lands and reduce agricultural clearances. So far 1,800 square kilometres of forest have been protected at a cost of $300 million, both safeguarding biodiversity and reducing greenhouse gas emissions to the tune of 3.2 million tonnes.⁵⁴ In the Maldives, whose government I work for as an environmental adviser, one of the schemes under consideration is a levy on diving trips to fund the creation and policing of marine parks. Thus those who benefit from biodiversity – the foreign tourists who marvel at the reef sharks, manta rays and myriad of brightly coloured reef fish that swim around Maldivian coral atolls – can be asked to pay to conserve it.

In other countries, ‘biodiversity credits’ are being designed that might offer a revenue stream rewarding those who protect and manage biodiverse habitats. In New South Wales, the state govern-ment’s environment department has set up a ‘BioBanking’ scheme where developers and landowners can trade biodiversity offsets. Some private companies have been making similar pioneering moves: in Borneo the local government has partnered with the Australian company New Forests to provide an income for the protection of its 34,000-hectare Malua Forest Reserve. Both individuals and businesses can purchase ‘Biodiversity Conservation Certificates’ that represent the ‘biodiversity benefits of 100 square metres of protection and restoration of the Malua Forest Reserve’ – habitat for ‘endangered wild orangutans as well as gibbons, clouded leopards, pygmy elephants, and over 300 species of birds’, according to the Malua BioBank website.⁵⁵

As with carbon offsets, aimed at mopping up an equivalent amount of greenhouse gases to those unavoidably released elsewhere, a partnership between businesses, governments and conservationist groups is currently developing the concept of biodiversity offsets. Their goal is to design offsets that compensate for biodiversity impacts arising from business activities like mining and dam-building, potentially raising considerable sums to protect and enhance ecosystems elsewhere. To count as offsets, schemes must be additional to what would otherwise have happened, provide benefits that last as long as the damage they are intended to address, and deliver equitable outcomes that bring benefits to local people and communities. In addition, offsets are recognised as only being appropriate as a last resort: the so-called ‘mitigation hierarchy’, in order of importance, is avoid, minimise, restore, and only then offset.⁵⁶ Like achieving carbon neutrality, the principle of ‘no net loss’ of biodiversity – or even better, ‘net positive impact’ – should and hopefully soon will become part of mainstream business practice.

Protecting natural systems can provide value for money even in the most direct sense. Creating marine protected areas enhances fish stocks, providing benefits both to biodiversity and fishermen in neighbouring areas. The World Bank and UN Food and Agriculture Organisation have estimated that $50 billion is lost each year in terms of economic benefits that could be realised if the world’s fisheries were managed sustainably.⁵⁷ It may seem counter-intuitive, but a reduction of fishing effort could lead to an increase in overall fish catch. This is a matter of life and death for the over 1 billion mainly poor people who are dependent on fish for their primary source of protein, and whose coastal fisheries have often been scoured out by foreign trawlers from rich nations whose own seas are exhausted.

But voluntary measures will only achieve so much. For biodiversity protection to really work, and for the funds to flow, it needs to be given the force of law. Here too recent progress gives cause for some qualified optimism. The Convention on Biological Diversity, long the poor relation of the Convention on Climate Change, enjoyed a boost in October 2010 with the agreement by world governments of a ‘Strategic Plan’ for the decade to 2020, intriguingly subtitled ‘Living in harmony with nature’. The Plan directs governments to mainstream biodiversity concerns ‘throughout government and society’, and to take ‘direct action … to restore biodiversity and ecosystem services’ by ‘means of protected areas, habitat restoration, species recovery programmes and other targeted conservation interventions’.⁵⁸ These requests are still voluntary at the international level, but national governments are encouraged to turn them into law to ensure that companies, individuals and institutions take biodiversity seriously.

Perhaps just as importantly, a new scientific body is being established, aiming to provide the same expert advice on biodiversity as the IPCC does on climate change. The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) could help finally put this issue at the top of the international scientific and policy agenda, compiling data and producing landmark reports that can inform the efforts of governments and other policymakers.

Biodiversity is an issue whose time has come. All we need to do now is figure out how to pay for it. Remember, all it will cost to save the tiger from extinction is a mere $82 million a year. Rather than passively lamenting its demise, we need to roll up our sleeves and start raising funds. If you do only one thing after reading this chapter, join this effort today.

Chapter Three

The Climate Change Boundary

That climate change is a planetary boundary will come as a surprise to no one. What may come as a surprise however is that the target that has been advocated by not just governments, but environmentalists too, has for years been much too weak. More recently that has begun to change: now an extraordinary coalition of more than a hundred governments and dozens of campaigning groups is lining up squarely behind a safe target for carbon dioxide in the atmosphere, as proposed by the planetary boundaries expert group. Although powerful countries like the US and China are a long way from endorsing this target – and the world economy is even further away from meeting it – the fact that such a crucial planetary boundary has attracted such a strong level of support is a serious piece of good news and one that deserves celebration.

Previous chapters explained how humanity has risen to global prominence through a massive exploitation of fossil energy resources. Human civilisation remains over 80 per cent dependent on fossil fuels worldwide, and as the economy grows so does the rate at which the carbon dioxide resulting from the burning of coal, oil and gas accumulates in the air. On average the carbon dioxide concentration of the atmosphere rises by about 2 parts per million (ppm) every year, from a pre-industrial level of 278 ppm to about 390 ppm today. Whilst the precise level of temperature rise implied by higher CO₂ is always going to be uncertain, it is indisputable that – all other things being equal – global warming will result from the human emission of billions of tonnes of greenhouse gases, sustained over more than a century.

Arguments over what would be a ‘safe’ level of atmospheric CO₂ have raged for decades. Back in 1992 the UN Framework Convention on Climate Change required in its much-cited Article 2 that the objective of international policy should be to avoid ‘dangerous anthropogenic interference’ in the climate system – but without defining what ‘dangerous’ actually meant. The British government’s Stern Review on the Economics of Climate Change of 2006 suggested a stabilisation target of 550 ppm CO₂e (carbon dioxide-equivalent, implying a bundling together of all climate-changing gases rather than only CO₂). Two years earlier, the European Union had endorsed a target of limiting temperature rises to 2 degrees Celsius, implying – it was stated – a CO₂ target of 450 ppm. This latter objective was endorsed in my 2007 book about climate-change impacts, Six Degrees, where I suggested that 2 degrees and 450 ppm were necessary to steer away from large-scale dangerous tipping points in the climate system. Major environmental groups also lined up behind similar targets, and pushed them hard at international meetings.

It turns out we were all wrong. A fair reading of the science today, as this chapter will show, points strongly towards a climate change planetary boundary of not 450 ppm but 350 ppm for carbon dioxide concentrations – a level that was passed back in 1988, the year that NASA climate scientist and planetary boundaries expert group member James Hansen first testified to the US Congress that global warming was both real and already under way. Hansen has done more than any other scientist to put the 350 number on the map. He was one of the first to realise its importance, and has become a tireless advocate of the actions that are necessary to meet it. It was Hansen’s discussions with the American author and activist Bill McKibben, indeed, that led to the creation of the worldwide movement 350.org. McKibben calls 350 ‘the most important number in the world’, and he is right.

Never mind the enduring global-warming controversies in the media; these are a distraction. The climate change planetary boundary is the one that is best understood, and that we know most about how to achieve. Moreover, meeting the boundary is a basic requirement for any level of sustainable planetary management: if CO₂ continues to rise, and temperatures begin to race out of control, then the biodiversity boundary, the ozone boundary, the freshwater boundary, the land use boundary and ocean acidification boundaries cannot be met either, and the remaining planetary boundaries are also called into question.

The climate boundary is humanity’s first and biggest test that will reveal early on whether we are truly capable of managing our environmental impacts in a way that protects the capacity of the biosphere to continue to operate as a self-regulating system. It is a testament to our intelligence that we have developed our scientific understanding so far that we now know a great deal about how the climate system works, and can define with some confidence where the planetary boundary should lie. It is perhaps testament to our stupidity, however, that despite decades of research and advocacy on climate, all pointing at the need to control greenhouse gas production, human emissions today continue inexorably to rise.

Thankfully the technologies and strategies that humanity needs to achieve the climate boundary are today no mystery. We have all the tools necessary to begin a wide-scale decarbonisation of the global economy, and to achieve this at the same time as both living standards and population numbers are rising rapidly in the developing world. But environmentalism will need to change at the same time. Much of what environmentalists are calling for will either not help much or is actually thwarting progress towards solving climate change. It is time for a new – and far more pragmatic – approach, that does not hold climate change hostage to a rigid ideology.

350: CURRENT EVIDENCE

First we need to establish whether 350 is actually the right number, and one that is supported by science. There are three broad lines of evidence that support the conclusion that atmospheric CO₂ concentrations need to be limited to 350 ppm. The first is the sheer rapidity of changes already under way in the Earth system, changes I never dreamt I would see so quickly when I started working on this subject more than ten years ago. These warn of looming danger. The second is modelling work suggesting that positive feedbacks – or thresholds, or tipping points, call them what you like – are getting perilously close. The third, and perhaps most conclusive, is evidence from the distant past linking temperatures with carbon dioxide concentrations in earlier geological epochs.

The best place to look for confirmation that our planet is gaining heat is not the air temperature at the ground, but the energy imbalance – the difference between incoming and outgoing radiation – at the very top of the atmosphere. There our sentinel machines, the satellites silently orbiting the planet twenty-four hours a day, show clearly that outgoing longwave heat radiation is increasingly being trapped at exactly those parts of the spectrum that correspond with the different greenhouse gases building up in the atmosphere below.¹ Natural variability is important in determining the average temperature each year, but recent records are revealing: the hottest year on record, according to NASA, is now tied between 2010 and 2005, with 2007 and 2009 statistically tied for second- and third-hottest.² Whatever the individual temperature records, the climatic baseline is visibly shifting: every year in the 1990s was warmer than the average of the 1980s, every year of the 2000s warmer than the 1990s average.³

There are now multiple lines of evidence pointing to ongoing global warming, some of which show that we are altering the characteristics of the atmosphere in unanticipated ways. Air-pressure distribution is changing around the world, with rises in the subtropics and falls over the poles.⁴ The stratosphere has cooled as more heat is trapped by the troposphere underneath,⁵ whilst the boundary between these two higher and lower atmospheric layers has itself increased in height.⁶ Even the position of the tropical zones has begun to shift as the atmosphere circulates differently in response to rising heat.⁷

A more energetic atmosphere also means more extreme rainfall events as the levels of water vapour in a warmer atmosphere increase: this too has been observed.⁸ The catastrophic flooding events that hit Pakistan in August 2010 and Australia in January 2011 are exactly the kind of hydrological disasters that will be striking with deadly effect more often in a warmer world. Whilst people in poorer countries are most vulnerable to the effects of floods, any country can be hit at any time: in the English Lake District the heavy rainfall event of 18–20 November 2009 had no precedent: rainfall totals outstripped previous all-time records in over 150 years of measurements.⁹

Perhaps the clearest indicator of current danger – Ground Zero for global warming – is the rapid thaw of the Arctic. Few experts argue any more about whether the sea ice sheet covering the North Pole will melt completely; merely when. In recent years the Arctic ice cap has entered what Mark Serreze, a climatologist at the National Snow and Ice Data Center (NSIDC) in Boulder, Colorado, calls a ‘death spiral’.¹⁰ The extent of Arctic ice is plummeting, and what remains is thinner and more vulnerable to melt than before. In terms of volume, less than half the ice cap of the pre-1980 era remains; more than 40 per cent of the volume of multi-year ice (the thicker stuff that lasts through the summer) has disappeared since only 2005.¹¹ Even the wintertime ice coverage is in decline: in January 2011 the NSIDC announced that the sea ice extent for that month was the lowest in the satellite record, with the Labrador Sea and much of western Greenland’s coast remaining completely unfrozen.¹² The year of what I call A-Day, the late-summer day at some time in the future when not a fleck of the North Polar floating ice remains, has been suggested by one modelling study as likely to arrive in 2037, but if recent years are anything to go by this could shift closer by as much as a decade.¹³

A-Day will be a momentous date for the Earth, for it will be the first time in at least five thousand years that the Arctic Ocean has been without any summertime sea ice.¹⁴ This will in turn alter the heat balance of the planet and the circulation of the atmosphere: without its shiny cap of frigid ice, the Arctic Ocean can absorb a lot more solar heat in summer and release much more in winter, changing storm tracks and weather patterns. The resulting prognosis is not for straightforward warming everywhere: one model projection by scientists working in Germany, published in November 2010, suggested that disappearing sea ice in the Arctic Ocean north of Scandinavia and Siberia could in fact drive colder winters in Europe. The researchers proposed that warmer unfrozen waters in the north could drive a change in wind patterns that allows cold easterly winds to sweep down into Europe and Russia, and that this may have helped cause the colder winters of 2005–6, 2009–10 and 2010–11 in both Europe and eastern North America, which have seen snowstorms and frosts even as the Arctic basked in unprecedented winter warmth. ‘Our results imply that several recent severe winters do not conflict [with] the global warming picture but rather supplement it,’ they concluded in the Journal of Geophysical Research.¹⁵

The disappearance of the Arctic ice will eliminate an entire marine ecosystem. Currently algae growing on the underside of floating ice are the base of a unique food chain, feeding zooplankton that in turn support large populations of Arctic cod.¹⁶ Rapidly diminishing ice spells disaster for ice-dependent species like ringed seals, walrus, beluga whales and, of course, polar bears. This may not necessarily mean outright extinction for the latter, but it will lead at best to a substantial reduction in their habitat.¹⁷ In May 2008 the polar bear was listed as ‘threatened’ under the US Endangered Species Act thanks to climate change.¹⁸

Given its current rate of precipitous decline, there is little hope that the Arctic ice cap’s death spiral can be arrested. But it is theoretically still possible to save or restore the frozen North Pole – by urgently retreating back within the 350 ppm climate boundary, and, as I will set out in a future chapter, by reducing emissions of other warming agents like black carbon. As NASA’s James Hansen, a member of the planetary boundaries expert group, writes: ‘Stabilisation of Arctic sea ice cover requires, to first approximation, restoration of planetary energy balance.’¹⁹ Reducing carbon dioxide levels to between 325 and 355 ppm would achieve this initial outcome, Hansen suggests – however, a further reduction, with CO₂ down between 300 and 325 ppm, ‘may be needed to restore sea ice to its area of 25 years ago’.

Serious climate impacts have of course also been identified outside the polar regions. In a June 2010 piece for Science magazine, climate experts Jonathan Overpeck and Bradley Udall – based at the universities of Arizona and Colorado respectively – wrote that ‘it has become impossible to overlook the signs of climate change in western North America’. These signs include ‘soaring temperatures, declining late-season snowpack, northward-shifted winter storm tracks, increasing precipitation intensity, the worst drought since measurements began, steep declines in Colorado River reservoir storage, widespread vegetation mortality, and sharp increases in the frequency of large wildfires’.²⁰ As with the melting of the Arctic, Overpeck and Udall reported that the impacts of global warming in western North America ‘seem to be occurring faster than projected’ in mainstream climate assessments like the IPCC’s 2007 report. In the Rockies higher temperatures mean that more winter precipitation is falling now as rain, and what snow does lie is melting earlier and faster. Peak stream-flow in the mountains of the American west now occurs up to a month earlier than it did half a century ago.²¹

One of the most worrying climate impacts mentioned by Overpeck and Udall in the western US is the rapid increase in tree death rates: more than a million hectares of piñon pine died recently due to drought and warming, and even desert-adapted species, that should be able to cope with ordinary dry weather, are ‘showing signs of widespread drought-induced plant mortality’. This climate-related forest die-off seems to be part of a serious global trend, which has seen widespread tree death observed in places as far apart as Algeria and South Korea, and dramatic reductions of forest cover even in protected areas like national parks.²² In some cases insect infestations are the immediate cause of the die-offs: in British Columbia beetle outbreaks have killed such extensive areas of boreal forest that experts estimate 270 million tonnes’ worth of carbon sink have been eliminated.²³

All over the world ecosystems face being wiped out as their climatic zones shift rapidly elsewhere – or disappear altogether. Just as polar animals are effectively pushed off the top of the world by the rising heat, so mountain-dwellers are confined to ever-shrinking islands of habitat on the highest peaks. Indeed, what is possibly global warming’s first mammal victim – the white lemuroid possum – may already have disappeared from its habitat of just a few isolated mountaintops in tropical Queensland, Australia. ‘It was quite depressing going back on the last field trip a couple of weeks ago, going back night after night thinking, “OK, we’ll find one tonight,”’ biologist Steve Williams told the Australian Broadcasting Corporation. ‘But no, we still didn’t find any.’²⁴ In Madagascar, another global biodiversity ‘hotspot’, mountain-dwelling species are already being displaced uphill, and some species of frog and lizard may now be extinct because of the changing climate.²⁵

Thermal stress also affects humans, of course, as increasingly intense and frequent heatwaves scorch our cities. Hundreds died in the August 2010 Moscow heatwave. Tens of thousands (and possibly as many as 70,000 in total²⁶) succumbed across continental Europe in the record-breaking summer of 2003. Very hot summers have already become more frequent across the Northern Hemisphere, and the risk of a repeat of the 2003 heat disaster has now doubled, thanks to global warming.²⁷ According to news reports, 2010 saw Japan endure its hottest-ever summer, whilst all-time heat records were smashed in 17 different countries.²⁸ Heatwaves have also increased in the Mediterranean region in number, length and intensity, according to the latest studies.²⁹ This warming and drying trend is repeated across much of the world: in southwestern Australia, for example, rainfall has fallen by a fifth since the 1970s, leading to permanent water shortages in Perth.³⁰

All these lines of evidence – of rising temperatures, thawing ice caps, shifting weather patterns and increasingly dangerous impacts – emphasise that limiting CO₂ concentrations at 350 ppm in order to prevent substantial future global warming is the only sensible option. Getting back within this planetary boundary would potentially restore the Arctic to health and prevent the complete thawing of mountain glaciers in the Andes and Himalayas that help sustain freshwater supplies to many millions of people. Limiting the speed and magnitude of the future temperature increase to just a degree and a half this century, the most likely outcome of a 350 ppm pathway, would keep global warming slow enough to allow both natural ecosystems like coral reefs and human societies to adapt to climate change.

350: MODELLING EVIDENCE

Observing the present allows us to extrapolate using educated guesswork towards the future. But perhaps a more scientifically rigorous way to project future climate change is to look at the output of complex computer models that simulate the way the climate operates in incredible detail. Taking months of supercomputer time to crunch all their complex equations, these modelling studies allow scientists to simulate changing conditions on Earth as CO₂ rises, ice melts and temperatures climb inexorably. Although computer models are always going to be an imperfect representation of the real planet we live on, they are the only way to run experiments into the future – other than sitting back and watching what really happens to the Earth, by which time it will be too late to do anything about it.

The point of setting a planetary boundary on climate is to enable humanity to keep on the right side of potential tipping points that could mark dangerous and potentially irreversible shifts in the way the biosphere operates. With that objective in mind, two members of the planetary boundaries expert group, Tim Lenton and Hans Joachim Schellnhuber, were co-authors of a landmark study published in 2008 that tried to identify the different tipping points that might exist in the climate system and get some idea of what level of temperature rise might trigger them.³¹ Top of the list was Arctic sea-ice loss. This is because the Arctic melt is self-reinforcing: as ice disappears, its highly reflective surface is replaced by darker sea or land, that absorbs more of the sun’s heat, allowing the melt of even more ice. The problem here is that models generally underestimate the observed loss of ice – in other words, what is happening in the real world tends to be worse than anything projected by the models. Given this, the experts concluded, ‘a summer ice-loss threshold, if not already passed, may be very close’. Only a 350 ppm target would likely prevent it, corresponding to 0.5 to 2˚C future global warming. But even this may not be enough.

Second on the tipping points list came the melting of Greenland’s vast ice sheet. Thick enough to raise the global oceans by seven metres if it melted entirely, the stability of Greenland matters hugely to faraway nations like Bangladesh and the Maldives, which face partial or total inundation (in the case of the latter) if it melts because of global warming. So where does the tipping point lie that might doom the Greenland ice cap to eventual destruction? Between just 1 and 2 degrees above today’s temperatures, the experts concluded, meaning that a 350 ppm trajectory is once again the least we will need to achieve to protect it. Here too the process could become self-reinforcing. The centre of Greenland is extremely cold because the thickness of the ice sheet means that it extends into high altitude: Greenland’s Summit Camp is located 3,200 metres above sea level. But as global warming nibbles away at the edges of this enormous ice body, more of it comes into the lower altitude zone, exposing the ice to higher temperatures and increasing the melt rate. Although eliminating a whole continent’s worth of ice will take time, the process could be completed in as little as three centuries, dramatically changing the coastal geography of the planet. Once again, this is a tipping point that humanity would be wise not to trigger.

Greenland is not the only vulnerable polar ice sheet, of course. Third on the list came the West Antarctic Ice Sheet, again of serious concern because – like Greenland – its loss could trigger multi-metre rates of sea-level rise. The West Antarctic also could be subject to a positive feedback process once a serious melt got under way, not just because of the change in altitude but because most of the ice sheet is actually grounded well below today’s sea level. As warming waters penetrate underneath the ice mass they could trigger a collapse that would be unstoppable, and would eventually raise global sea levels by another 5 metres. Here we may be on slightly safer ground, as the experts conclude that a global warming of 3–5˚C will likely be necessary to lead to complete collapse. So the 350 ppm boundary would appear to be well within the safety margin according to the models.

As with the Arctic sea ice, however, the real world may prove the models of Greenland and the West Antarctic to be overly conservative. The most recent satellite data from the GRACE (Gravity Recovery and Climate Experiment) mission shows a doubling in ice mass lost from both Greenland and Antarctica over the last decade³² – despite a thickening of Greenland’s higher interior where warmer winds have increased snowfall rates. Until recently the massive East Antarctic ice sheet was probably stable, but it too began losing ice in coastal areas after about 2006.³³ In total the Earth’s great ice sheets are now shedding a few hundred billion tonnes of ice annually, and sea levels rising by slightly more than 3 mm per year as a result – nearly double the rate for most of the twentieth century.³⁴ A rise in sea levels by 2100 of somewhere between 60 cm and 1.6 metres is now on the cards,³⁵ substantially more than was suggested just a few years ago by the IPCC.³⁶

A more familiar tipping point was examined next, one that has even been made into a dramatic Hollywood film. In The Day After Tomorrow, a sudden ice age is seen flooding and then freezing New York (why is it always New York?) after global warming destabilises the circulation of the Atlantic Ocean. Although the flash-freezing depicted in the movie is thermodynamically impossible, the scenario of a collapsing Atlantic current is not complete science fiction. All the models examined by the expert group led by Tim Lenton showed a tipping point in the North Atlantic where warmer, fresher waters could shut down the circulation pattern that brings comparatively balmy temperatures to the eastern US and high-latitude Western Europe. This shutdown would not trigger a new ice age, but temperatures in these regions could fall for several decades, causing serious impacts on societies and ecosystems alike.³⁷ Again unlike the Hollywood movie, which showed temperatures dropping in seconds, the full transition towards an Atlantic Ocean circulation shutdown would likely take a century or more. More good news is that avoiding this tipping point is still possible: the scientists conclude from studying their models that a global warming of 3–5˚C would be needed to put us in the danger zone, well above the 1.5˚C maximum warming implied by our 350 ppm planetary boundary.

Another candidate on the tipping-point list is the Amazonian rain-forest. For years now many scientists have warned that global warming could trigger a collapse of the forest if rising temperatures lead to severe drought in western Brazil. This scenario seems even more of a danger given the recent droughts experienced in Amazonia in both 2005 and 2010, where entire river systems in this normally wet forest dried up for hundreds of kilometres. The problem here is that models don’t concur: some show a warmer Amazon getting wetter, whilst the most pessimistic forecasts for Amazon die-back are based on the projections of just one model, the HadCM3 model produced by the UK Met Office’s Hadley Centre. However, half of the 19 different models examined by a team of scientists led by Oxford University’s Yadvinder Mahli in 2009 did show a shift towards more seasonal forest, and a quarter showed that the rainforest could dry out sufficiently to collapse into a savannah-type ecosystem instead.³⁸ Keeping global temperatures below 3˚C – very likely if our 350 ppm planetary boundary is achieved – should be enough to avoid this transition, but just as important will be respecting the other planetary boundaries on land use and biodiversity loss. The Amazon rainforest today is probably more threatened by deforestation and agriculture than it is by rising temperatures.

If the Amazon rainforest did collapse, huge quantities of carbon would be released in the process, giving a further boost to global warming. But the biggest carbon stores of all lie not in the tropics, but in the sub-polar continental regions where frozen permafrost holds enormous carbon stores tens of metres thick in Siberia and other high-latitude land areas. The threat to permafrost stability is possibly global warming’s biggest tipping point, because if this frozen carbon store begins to thaw, vast quantities of both carbon dioxide and methane will be released. According to a 2008 study in the journal BioScience, the carbon locked up in the Northern permafrost zone totals more than 1.5 trillion tonnes, double the entire carbon content of the atmosphere.³⁹ Even if only 10 per cent of this permafrost thaws, another 80 ppm of CO₂ will have accumulated in the atmosphere by 2100, raising the planet’s temperature by an additional 0.7 degrees⁴⁰ – and making the eventual attainment of the 350 ppm climate change boundary much more difficult.

Scientists have already begun watching with some alarm a recent upward trend in atmospheric methane, some of which may be coming from the Arctic.⁴¹ Not all this methane – a greenhouse gas 25 times more potent than CO₂ – is likely to bubble out of swamps on land; vastly more is contained in subsea sediments in the form of ice-like methane hydrates. If these hydrates melt rapidly as the oceans warm up, then all global warming bets are off – a scenario that has already sparked scary newspaper headlines. So how afraid should we be? Researchers have already reported seeps of methane leaking from the seabed offshore from eastern Siberia and the Norwegian Arctic islands of Svalbard, in both cases possibly in response to warmer ocean waters.⁴² But the experts are cautious. ‘Methane sells newspapers, but it’s not the big story,’ writes David Archer on the excellent RealClimate blog.⁴³ ‘CO₂ is plenty to be frightened of, while methane is frosting on the cake.’

Work by Archer and colleagues modelling the Earth’s response to climate change suggests that methane hydrate release could add another half-degree or so to the total warming, but only over several thousand years, and only if the released methane is not dissolved or oxidised first in the ocean before it has time to escape into the atmosphere.⁴⁴ This is a ‘slow tipping point’, Archer concludes: it takes a long time for warming to penetrate the oceans, even longer for this to melt and release hydrates, and longer still for this methane to warm the atmosphere and the oceans further in a positive feedback loop. Happily, this is a tipping point we have still not crossed – ‘We have not yet activated strong climate feedbacks from permafrost and CH₄ [methane] hydrates,’ reported a team of scientists in 2009.⁴⁵ In the case of methane hydrates, respecting the climate boundary is not necessarily about protecting ourselves or even our children, but the stability of the Earth system over the very long term – for this tipping point, while slow to activate, would be essentially irreversible once crossed.

350: PAST EVIDENCE

If current observations of accelerating climate change and worries about tipping points in the future make two very good reasons why 350 ppm is the right place for a climate change planetary boundary, even stronger evidence comes from the Earth’s more distant climatic past. Climate models projections such as those published by the IPCC tend to project nice smooth – albeit upward-pointing – curves of likely future temperature trends. But a glance back in time, courtesy of ice-core records drilled in Greenland and Antarctica, shows that gentle, slow changes are far from being the norm in the Earth’s past. Instead, these records of past climate – which now reach back almost a million years – show climatic swings of extraordinary and terrifying abruptness. One extremely sudden warming took place in Greenland 11,700 years ago; it involved a temperature rise of 10 degrees Celsius within just three years.⁴⁶ Rapid shifts are observed elsewhere too: 12,679 years ago, according to sediments recovered from a lake in western Germany, the European climate saw a sudden transition to more stormy conditions between one year and the next.⁴⁷ The lesson is clear. Abrupt climate change is not the exception in the past, it is the norm. As the veteran oceanographer Wally Broecker says: ‘The climate is an angry beast, and we are poking it with a stick.’

Although current CO₂ levels are higher than they have been for a million years, if we look even further back into the geological past there are episodes when both carbon dioxide and temperatures were far above where they are now. But rather than suggesting we have nothing to worry about, they further strengthen the evidence for counting 350 ppm as the crucial planetary boundary. For example, during the Pliocene epoch, about 3 million years ago, sea levels were 25 metres higher than today because the major ice sheets were much smaller than now due to a warmer climate. The CO₂ concentration then? About 360 ppm – a line we crossed in 1995.⁴⁸

The Earth was completely ice-free – and sea levels 80 metres or more higher – until about 33 million years ago, early in the geological epoch called the Oligocene. After having been at 1000 ppm or higher throughout the Cretaceous, Eocene and Paleocene, this was the moment when CO₂ levels dropped past a crucial threshold allowing continental-scale ice sheets to form on Antarctica for the first time in perhaps a hundred million years.⁴⁹ This CO₂ level was 750 ppm, a level expected to be crossed again in about 2075 if carbon emissions continue to rise unabated. For the following 31 million years, only Antarctica held substantial ice sheets – until, late in the Pliocene, the more recent ice-age cycles began. There was another CO₂ threshold at play here, one that allowed Northern Hemisphere ice sheets (such as the current one on Greenland) to form for the first time. That level was 280 ppm, which we crossed right at the start of the Anthropocene at the turn of the nineteenth century. Were Greenland to be ice-free at the moment, in other words, CO₂ levels are already too high for an ice sheet to form. Once again, 350 ppm seems to be the minimum necessary to protect the big polar ice sheets over the longer term.⁵⁰,⁵¹

NASA’s James Hansen (a member of the planetary boundaries expert group) wrote in the introduction to his landmark 2008 paper ‘Target Atmospheric CO₂: Where Should Humanity Aim?’ (published with nine co-authors in the open-source journal Open Atmospheric Science Journal): ‘If humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted, paleoclimate evidence and ongoing climate change suggest that CO₂ will need to be reduced from its current 385ppm to at most 350ppm, but likely less than that.’⁵² Hansen and his colleagues reject a target of 450 ppm, for long the objective of both many governments and environmental groups. ‘A CO₂ amount of order 450ppm or larger, if long maintained, would push Earth toward the ice-free state,’ they maintain. And although the inertia of the climate system and slow response-times of ice sheets would limit the speed of this change, ‘such a CO₂ level likely would cause the passing of climate tipping points and initiate dynamic responses that could be out of humanity’s control’.

TOWARDS A TECHNOFIX?

Having said all that, solving climate change is actually a lot simpler than most people think. Global warming is not about overconsumption, morality, ideology or capitalism. It is largely the result of human beings generating energy by burning hydrocarbons and coal. It is, in other words, a technical problem, and it is therefore amenable to a largely technical solution, albeit one driven by politics. I often receive emails telling me that fixing the climate will need a worldwide change in values, a programme of mass education to reduce people’s desires to consume, a more equitable distribution of global wealth, ‘smashing the power’ of transnational corporations or even the abolition of capitalism itself. After having struggled with this for over a decade myself, I am now convinced that these viewpoints – which are subscribed to by perhaps a majority of environmentalists – are wrong. Instead, we can completely deal with climate change within the prevailing economic system. In fact, any other approach is likely doomed to failure.

Here are two options that certainly won’t work. First, we could try to reduce the global population. Certainly, fewer people by definition means lower emissions. But getting to 350 ppm by reducing the number of human carbon emitters on the planet is impossible as well as undesirable: at a first approximation it would require the number of people in the world to be reduced by four-fifths down to just a billion souls or less. Short of a programme of mass forced sterilisation and/or genocide, there is no way that this could be completed within the few decades necessary. Certainly there are a multitude of reasons why giving people access to family planning is a good idea, but climate-change mitigation is not among them. The best reason for promoting birth control is that people want it, and everyone should be able to choose how many children they have. The future of the planet doesn’t come into it.

The second option is to restrain economic growth, as GDP is very closely tied to the consumption of energy and therefore carbon emissions. No one disputes that recessions do tend to reduce emissions: the global financial and economic crisis that began in 2008 led to a fall in CO₂ emissions worldwide by 1.3 per cent within a year.⁵³ But imagine that the recession had been caused not by solvency problems within financial institutions but by government policies to tackle climate change. Jobless totals would be rising, government cutbacks in welfare services hitting the poor, and a new age of austerity dawning – all because of the tree-huggers. If you thought the debate on climate change was ill-tempered now, imagine that particular future and its implications.

Greens have for years called into question GDP as a measure of true progress, but the reality is that increasing prosperity – measured in material consumption – is non-negotiable both politically and socially, especially in developing countries. This may one day need to change, but that is a different debate, and one that needs to be had for different reasons. As the climate scientist Roger Pielke Jnr writes in his 2010 book The Climate Fix, ‘if there is an iron law of climate policy, it is that when policies focused on economic growth confront policies focused on emissions reductions, it is economic growth that will win out every time.’ Greens may despair, but I think Pielke Jnr is right. The implication, however, is not that we are all doomed, but that any successful policy to decarbonise the global economy ‘must be designed such that economic growth and environmental progress go hand in hand’.⁵⁴

In a related sense, although Greens often insist that energy is too cheap, this too is incorrect. Energy is actually too expensive, certainly for the 1.5 billion poor people in the world who lack access to electricity because they do not have the purchasing power to demand it. Well-fed campaigners in rich countries may fantasise romantically about happy peasants living sustainably in self-reliant African villages, but the fact is that people across the developing world are desperate to increase their economic opportunities, security and wealth. They want to have enough to eat, they want to have clean water and they want their young children not to die of easily treatable diseases – and that is just for starters. They want the benefits of being part of the modern world, in other words, which is why so many young people across the developing world are moving to cities in search of a job and a better way of life. And this better way of life is coming, as the soaring rates of economic growth in China, India, Brazil and many other developing countries demonstrate. The fact is that most of the world needs more growth, not less: China has lifted 300 million people out of poverty in the last couple of decades due to its economic miracle. Hundreds of millions more, in Africa now too as well as Asia and Latin America, are determined to follow, as they have every right to.

By mid-century, in other words, we will see a world of many more, much richer people. Most Greens view this prospect with dread, for how can the world possibly reduce carbon emissions under such a scenario? The London-based New Economics Foundation (NEF), for example, writes in a recent report: ‘If everyone in the world lived as people do in Europe, we would need three planets to support us.’⁵⁵ This is nonsensical, for everyone in the world is going to live like Europeans within this century (and Europeans too will also get richer) whether NEF likes it or not, and we will still only have one planet. NEF’s ‘Happy Planet Index’ was recently topped by Costa Rica (with the Dominican Republic in second place and Jamaica in third), apparently suggesting that the best country in the world to live is one where 10 per cent of the population still survive on just $2 a day.⁵⁶ Certainly, the fact that GDP does not necessarily equate to happiness is an important point to make. But it won’t cut much ice with the billions of people – a majority of humanity – who are poor, insecure or malnourished in today’s world. For them economic growth is not a choice but a necessity.

So reducing human population and economic growth is neither possible nor desirable. Luckily there is a third way: we can reduce the carbon intensity of the economy, so that for each unit of GDP produced, less and less carbon needs to be emitted. This means deploying low-carbon technologies across the board so that the energy that is needed to drive economic activity can be generated without additional greenhouse gases. What we need, in other words, is an economy-wide technofix.

TECHNOLOGIES FOR 350

My own perspective on tackling climate change has shifted since I was appointed adviser to President Nasheed of the Maldives in 2009. The president, whose country is of course early on the list of those liable to be wiped out by rising sea levels, had just announced his ambition for his nation to become the first carbon-neutral country in the world, by 2020. Suddenly, having spent most of my life as a journalist, I was confronted with the challenges of real energy supply in a real developing country. All my Green ideology – of tackling corporate power, reducing consumption, challenging economic growth and so on – was going to be of little help with this intensely practical challenge. To be carbon-neutral the Maldives would have to stop burning diesel in electric generators on every one of its 300 or so inhabited islands, and shift instead to an energy system entirely based on renewables. It would have to do this in a way that would not raise people’s energy bills, and would provide opportunities for new business. I found myself in a world where discussions of wind and solar hybrids, battery storage options, biomass and waste-to-energy, and electrical grid load-balancing came to the fore. I began to think less like an ideologue and more like an engineer.

This, on a far grander scale, is the same challenge that confronts the world. To achieve the planetary boundary of 350 ppm, the global economy needs to be carbon-neutral by mid-century and carbon-negative thereafter. Meeting this target means we all – Greens included – need to start thinking like engineers. This is a huge industrial building project, converting the energy basis of civilisation from fossil fuels to a variety of cleaner sources. If we do it right, it will not be a burden or a cost to the world’s economy, but a source of enormous potential future growth, innovation and job creation. The sheer amount of economic activity implied by the transition is staggering: to reduce the emissions of the United States by a third, for example, would (using current technologies) involve constructing 145 nuclear plants, 33,000 solar thermal power stations and 130,000 large wind turbines. In Germany, the same ambition of a 30 per cent emissions cut implies 21 nuclear plants, 4,800 solar stations and 20,000 additional windmills.⁵⁷

Different technologies can be substituted according to different circumstances or national preferences, of course. The Austrians, for example, despise nuclear power. (The country spent $1 billion building a nuclear plant, and then had a referendum in 1978 that was won by the anti-nuclear lobby. The plant, called Zwentendorf, was never opened, and coal-burning power stations built instead.) For the Maldives I would not suggest any nuclear power stations, because each island operates as a separate independent energy entity and nuclear plants are simply too big to be appropriate. Moreover, the country is drenched in solar radiation for most of the year – its main constraint, in fact, is the land space needed to capture the sun’s energy. But very large, densely populated nations outside the tropics are likely to need substantial nuclear generation. This may be difficult for many Greens to swallow, but as I will show in future chapters, nuclear power is nothing like the environmental threat it has long been made out to be. Instead, by displacing coal from our energy mix, it can be a net win for the biosphere. China, for instance, has 13 operational nuclear plants and 150 more under construction or on the drawing board.⁵⁸ Each 1-gigawatt nuclear plant will displace 6 million tonnes of annual CO₂ emissions, making this one of the best pieces of climate-related news anywhere in the world.⁵⁹ That should be the end of the matter so far as environmentalists are concerned: nuclear is Green.

To cut global emissions in half by 2050 (with growing energy consumption in the meantime) would require the construction of 12,000 nuclear power stations – with one plant coming online every single day between now and then (assuming we start in 2015). I mention this only as an illustrative exercise, for no one – not even the nuclear industry – suggests that we try to deal with climate change using nuclear power only. Such a level of new-build sounds impossible, but consider that over the last fifty years humans have constructed two large dams per day, half of those in only one country – China.⁶⁰

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