скачать книгу бесплатно
(#litres_trial_promo) 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.
(#litres_trial_promo)
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.
(#litres_trial_promo) (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.
(#litres_trial_promo) 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.
(#litres_trial_promo) 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.
(#litres_trial_promo)
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.
(#litres_trial_promo) 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.
(#litres_trial_promo) After a decade, just 5–10 per cent of the original coral cover was left,
(#litres_trial_promo) and little more remains to this day.
(#litres_trial_promo) 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.
(#litres_trial_promo) 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.
(#litres_trial_promo) 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.
(#litres_trial_promo) 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.
(#litres_trial_promo)
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.’
(#litres_trial_promo) 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).
(#litres_trial_promo)
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.
(#litres_trial_promo) ‘The flows of ecosystem services can be seen as the “dividend” that society receives from natural capital,’ the TEEB Synthesis Report suggests.
(#litres_trial_promo)
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.
(#litres_trial_promo) 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.
(#litres_trial_promo) 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.
(#litres_trial_promo)
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.
(#litres_trial_promo) 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.
(#litres_trial_promo) 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’.
(#litres_trial_promo) 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 CO
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 CO
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 CO
e (carbon dioxide-equivalent, implying a bundling together of all climate-changing gases rather than only CO
). Two years earlier, the European Union had endorsed a target of limiting temperature rises to 2 degrees Celsius, implying – it was stated – a CO
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 CO
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 CO
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.
(#litres_trial_promo) 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.
(#litres_trial_promo) 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.
(#litres_trial_promo)
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.
(#litres_trial_promo) The stratosphere has cooled as more heat is trapped by the troposphere underneath,
(#litres_trial_promo) whilst the boundary between these two higher and lower atmospheric layers has itself increased in height.
(#litres_trial_promo) Even the position of the tropical zones has begun to shift as the atmosphere circulates differently in response to rising heat.
(#litres_trial_promo)
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.
(#litres_trial_promo) 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.
(#litres_trial_promo)
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’.
(#litres_trial_promo) 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.
(#litres_trial_promo) 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.
(#litres_trial_promo) 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.
(#litres_trial_promo)
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.
(#litres_trial_promo) 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.
(#litres_trial_promo)
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.
(#litres_trial_promo) 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.
(#litres_trial_promo) In May 2008 the polar bear was listed as ‘threatened’ under the US Endangered Species Act thanks to climate change.
(#litres_trial_promo)
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.’
(#litres_trial_promo) Reducing carbon dioxide levels to between 325 and 355 ppm would achieve this initial outcome, Hansen suggests – however, a further reduction, with CO
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’.
(#litres_trial_promo) 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.
(#litres_trial_promo)
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.
(#litres_trial_promo) 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.
(#litres_trial_promo)
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.’
