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