скачать книгу бесплатно
The God Species: How Humans Really Can Save the Planet...
Mark Lynas
Originally published as The God Species: How the Planet Can Survive the Age of HumansThe green movement has got it very wrong.Nature no longer controls our planet – it is humanity, ‘the god species’, that must save the environment we have inflicted unprecedented damage upon. And the tools we must use are the very technologies that environmentalist have told us for years will spell disaster: nuclear power, GM food and geo-engineering.In this blistering and urgent manifesto, Mark Lynas identifies a new future for the green movement and an entirely fresh agenda for how we will save the Earth, and ourselves.
MARK LYNAS
The God Species
How the Planet Can Survive
the Age of Humans
Dedication (#u1d9e4d14-f3ad-5fb4-9f25-56c4c20e765f)
For my family and other animals
Contents
Cover (#u522db0ff-0ec8-533b-acb8-da181ef45d60)
Title Page (#u250bd916-af18-508e-a14e-ba153e22e9d2)
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 (#litres_trial_promo)
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 CO
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.’
(#litres_trial_promo) QED, as I think they say.
(#litres_trial_promo)
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.
(#litres_trial_promo)) 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 CO
. 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 space
(#litres_trial_promo). 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.
(#litres_trial_promo) 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 H
O 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 CO
, but also in combination with other elements, such as with hydrogen as CH
(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 CO
-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 CO
. 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 CO
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 CO
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 CO
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).
(#litres_trial_promo) 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 million
(#litres_trial_promo). 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.
(#litres_trial_promo) 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.’
(#litres_trial_promo) 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.
