Читать книгу The God Species: How Humans Really Can Save the Planet... - Mark Lynas - Страница 7

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.