With apologies to Bill Clinton and Jean Charest
The word is in: we are now deep into the world’s Sixth Great Extinction. Over the 543 million years of the Phanerozoic Eon, that vast period in which life made itself abundantly evident in the fossil record, there have previously been five events that have effected an enormous change in the composition of life on Earth.
The best known of these, the asteroid collision that brought down the terrestrial dinosaurs 65 million years ago, is as rooted in our imaginations as a science fiction thriller. It has been estimated that up to 50% of animal species were extinguished at that time
The most serious, the Permian extinction of 250 millions years ago, wiped out 96% of marine species and over 70% of land vertebrates. It is the only known mass extinction of insects, which are critical today in the proper functioning of ecosystems (yet ever targeted in our economic cross-hairs).
In the end, the extinction we face now may well rank up there with those two, if there is anyone left to do the ranking.
The causes of the other three of these extraordinary transformations are the subjects of considerable scientific debate, even while paleontologists work to fill in the details. Severe glaciation, super-volcanism, bolide or “large body” impacts, gamma ray bursts from supernovas, destabilized methane hydrates (clathrates) — all factor among the plausible explanations for what seems on the face of it implausible: the eradication of vast swathes of life across our planet. That these events could possibly have taken place in the distant past, whether due to the reasons hypothesized or to others not yet imagined, is in itself incredible. That human activities could be responsible for something of comparable scale is in the minds of most members of the public, and the politicians they elect, inconceivable.
And yet the great global winking out of life, at the hands of mankind, is forcing itself into consciousness. It is real and it will impose itself upon us, in the years ahead, as a waking nightmare.
From the beginnings of the environmental movement nearly a half century ago, we have been bombarded with apocalyptic visions of what might become of us, our planet and the civilization we believe sustains us. Rooted deeply in our cold war preoccupations was a fear of a different sort of global heating than what dominates our thinking now, a thermo-nuclear cataclysm of our own making. It was assumed to be a consequence far more dreadful than any that might have emerged from the global hot-war that preceded it. Then, there came Rachel Carson’s Silent Spring to layer upon that a whole new problem to harrow ourselves with, a horrific vision made manifest in peregrine falcons, brown pelicans and other sensitive wildlife being threatened with oblivion. Atomic and chemical onslaughts, potential and real, presented us with the prospects of a world emptied of life as we knew it, including our own. The civilized world tried to fit these matters into its political social and economic reckoning. Then, as now, admonition was met with denial. “We are not that powerful. Nature is resourceful and always bounces back.”
With the older threats lingering in the background, we moved on to new ones: phosphates and pollution of lakes, rivers and seas; acid rain and the destruction of lakes and forests; nuclear power plant meltdowns, aka the China Syndrome; depletion of the protective ozone layer by CFCs and harmful exposure to ultraviolet radiation; overexploitation and contamination of freshwater sources; soil erosion and desertification; and, of course, Climate Change.
Always there has been the reassurance given that “With a bit of ingenuity, and a percentage point taken off the top of GDP, we can work the fixes needed.”
There has been, forever, it seems, the layering of new dangers upon old and the eliciting of fears that with time appear unfounded. We are still here, of course, and we have the comforting reassurances from such as Bjorn Lomborg, author of The Skeptical Environmentalist, that life has never been longer, nor healthier, nor more prosperous than it is right now. We eat a rich variety of foods brought from the four corners of the planet, drive the latest model cars, use the latest iGadgets and fly to some exotic holiday location, all the while paying down the mortgage and those credit card balances. Yes, there are the periodic global financial blips, but they have proved to be manageable and transitory. The environmental “crises” will prove the same. Technology and human ingenuity will always step forward to bail us out. What’s to worry?
Planetary morbidity, that’s what. And each of the eponymous crises contributes, in its own way, to the regression. The real significance of each lies in how they impact the biosphere. It is a far from comprehensive listing.
Since the emergence of our species, Homo sapiens, and especially since the rise of our civilization after the last ice age, mankind has sought willfully to have dominion, as a divinely sanctioned birthright, “over the fish of the sea and the birds of the air and every creature that moves on the ground.” The more we humans have succeeded in transforming the globe to our own ends, the more we have felt justified in doing so. And so today, even in extremis, we continue to believe that we ought “be fruitful and multiply.” The Earth remains, in our thinking, ours to subdue, its riches ours for the taking. There are very few pristine places left on Earth, virtually nowhere to escape the dreadful spoor of our kind. Our ecological footprint is enormous and growing and jeopardizes the economic resource bases of all other living things (see www.rprogress.org/ecological_footprint/about_ecological_footprint.htm) — except, of course those whose needs are compatible with our own and happily keep our company, notably Norway rats, fast-food gulls, houseflies and dandelions. Economic growth still dominates our present mindset, the words repeated mantra-like by our political, corporate and financial pundits. Yet, take note, unconstrained growth is what characterizes cancer, which untreated, as we know, is terminal.
Our association with species loss is not something recent, rather something that appears to have been ongoing since we migrated out of Africa 100,000 years ago. The paleontological record is replete with the extinctions of many extraordinary species concurrent with our progress across the planet. Certainly, periodic climate change could factor in as a major stressor for large animal species, or megafauna, through that timespan, but there is more than a reasonable likelihood that humans were present to push animal populations past the tipping point into extinction. We entered Europe, Asia and from there Australia and the “New World” as an alien species with which indigenous species were ill-equipped to cope. As E.O. Wilson writes in The Future of Life:
“Like the rats, pigs, and assorted diseases they carried with them, they [human beings] met few co-evolved prey and enemies. Adapting to the new environments by culture at a rate thousands of times faster than possible with genes alone, they outpaced any defense that the resident biotas could raise.”
So, then, the great slaughter, of creatures ill-prepared to cope with us interlopers, began. The cave paintings at Lascaux and other sites in France and Spain reveal our hunters’ fascination with such game as aurochs (precursors of domestic cattle), bison, mammoths, horses, lions, hyenas, cave bears and other large animals now long since gone from the wild. Modern man’s arrivals in Australia, New Zealand, North and South America all appear as smoking guns in the case for megafauna exterminations in those places. Our history, going back to the exit from our African cradle, is filled with unhappy examples of our rapacity, behaviour that continues unabated even now in 2010, the International Year of Biodiversity.
Says Wilson “Among the lessons learned is that the decline of any particular species rarely has a single cause. Typically, multiple forces entrained by human activity reinforce one another and either simultaneously or in sequence force the species down.” Wilson, and other conservation biologists, looking to represent the discrete forces at work that reduce the diversity of species and ecological systems, use the acronym HIPPO which stands in for: Habitat destruction, Invasive species, Pollution, Population and Overharvesting. Wilson posits that these forces, other than human population growth, descend in order of importance in the same sequence as the letters HIPPO, with Habitat Destruction having the most devastating effect. He claims that, in the time of our primeval ancestors, the sequence would be the reverse, OPPIH, with overharvesting being the main culprit.
The troubling mechanics of habitat destruction are summed up best in the area-species principle. Simply put, a 90 percent reduction in habitat area allows half of the species to hang on while the other half is eliminated. We might be beguiled by the tenacity of half the species to cling on while most of their habitat is gone, but the loss of the last ten percent, of course, takes all the species with it. Clearly the species losses at the beginning of this accelerative process are not as severe as they are towards the end. As Wilson points out, “The clearcutting of a remnant patch of mountain rainforest can eliminate scores of species in one stroke.” And he reminds us that, globally, the number of habitat fragments at ten percent or less of their original extent is growing rapidly.
If the depredations of invasive species are given second billing, they surely can’t be far from the top in the severity of their impacts. Consider well that the scale of destruction just mentioned has been the handiwork of the preeminent invasive species — us. The devastation we wreak derives from “intelligent” choice, and if we can see the light in time, we might wisely choose to mitigate our impacts. By avoiding the most sensitive ecosystems remaining, while rehabilitating those we have savaged, we might yet save a significant proportion of the species and habitats we have brought to the brink. However, we, the ultimate invasive, will bear witness, hour by hour and day by day as species losses continue to mount. And the passing of many species will go unknown.
While we humans have uniquely sensitive, though far from infallible, powers of prognostication, not so the many alien kind we have drawn in our wake to the World’s further reaches. The species we have introduced to new frontiers, from the great landmasses to the tiniest islands and from the great oceans to inland seas and rivers, number in their inestimable thousands. Even though introduced species compete for space and resources with native ones, most are relatively benign and may coexist in peace. But the ecological record is replete with horror stories of invasives that have proliferated wildly and driven indigenous species into extinction.
Problematic species that we have, sometimes purposefully and other times unwittingly, relocated to new homes simply obey the directives written into their genomes. They are in this respect innocent — something to which we cannot make claim. Yet they nonetheless work their harm by aggressively out-competing native species for food and habitat or by preying upon them. They may also be major transmitters of deadly diseases. On all counts, the ship rat, which stowed away in the holds of our ships, qualifies. Its impact on sensitive ecosystems worldwide, and particularly on small islands with unique flora and fauna, has been extreme. Feral dogs and cats, our erstwhile companions, also hunt to devastating effect on birds and mammals. Garlic mustard and common buckthorn are two common problematic invasives, among others, in Quebec, and other parts of North America, that have the power to transform forest ecosystems by supplanting native plants and denying food for forest animals to which they are unpalatable. Both are allelopathic, which means they release chemicals to the soil that discourage the germination and growth of native competitors. Proliferation of aggressive organisms of any kind puts in train an inexorable process of ecological simplification, that will run its course in its own time. It takes on a life of its own, its imperative to lead, not follow, until it is done.
Pollution is something that human kind is particularly good at. Our ingenuity has allowed us to create synthetic compounds that have now dispersed themselves pole to pole and throughout the Earth’s biomes. We have only to consider the chlorofluorocarbon crisis of the early 1980s that thinned out, and opened up two vast polar holes in, the atmospheric ozone layer that shields all life from the deadly menace of ultraviolet exposure. Our purposeful chemical assault on insects and other “pests” has had many unanticipated and counterproductive consequences. Here, with Rachel Carson’s indictment of pesticides 48 years ago, was the genesis of the environmental movement. But the toxic war on nature continues. A modern case in point — Dr. Tyrone Hayes’ revelations about the hormonal impacts of atrazine, an herbicide of choice, on frogs. He is a target of the corporate denial machine just as Carson had been. Add to this that our artificial world of throwaway plastics has become a planet-wide death machine.
As the human population continues to burgeon, so, too, will our impacts magnify. By mid-century we will add 2 billion people to our current population approaching 7 billion, all with rising expectations. Our numbers now are approaching 1000 times what they were at the end of the ice age 10,000 years ago.
A single biome, the oceans, illustrates how desperately impoverished we can render the natural systems that sustain us, through overharvesting. Since the turn of the twentieth century, humanity has depleted fisheries stocks by up to a staggering 90%. And our rising population will be vying to eat the rest. Top of the food chain predators such as oceanic white tip sharks are hunted for their fins while the rest of the animal is dumped back into the sea. Their numbers, once estimated to be the greatest among sharks, have been decimated by 70% during the last four decades, and they are now listed on the International Union for the Conservation of Nature, IUCN, Red List as Vulnerable. Other sharks also face precipitous declines. It is predicted that breeding populations of Atlantic Bluefin Tuna, a top predator and favourite in Japanese sushi restaurants, will be extinct by 2012. Jellyfish are now rising in rank to that of dominant predator in many seas as overfishing eliminates competitors. The last time they occupied this niche uncontested was half a billion years ago. Meanwhile, small lower food chain species like menhaiden are vacuumed up by factory ships to be used as pet food and fertilizer.
The web of relationships among living things within is complex and dynamic. Species within webs exercise, at once, mutual control and support, all the while undergoing evolutionary renewal and submission to the normal rate of extinction. It would appear that species loss in the intimately woven fabric of the biosphere has accelerated alarmingly to 1,000 to 10,000 times normal, according to the IUCN, in recent decades. The plight of the remarkable migratory shore bird, the red knot, pushed overnight to the edge of oblivion, illustrates brilliantly how fragile the links of interdependency among species can be.
James Lovelock speaks about the close-coupling of the biosphere with the lithosphere, Earth’s rocky crust; with the hydrosphere, that fills the abyss and washes over and through the land; and with the atmosphere, the gaseous envelope that has most recently consumed our attentions. This vital, bio-physical entity Lovelock, a serious scientist and no New Age hippy, has lovingly dubbed Gaia, after the Greek Earth Mother.
He reminds us that through 3 to 4 billion years she has given rise to all the life forms we now know. That she, at each stage of her maturation, tailored the atmosphere to her liking. She has managed the land and the waters and the air to optimize the flourishing of increasingly diverse life, never richer than it has been now. She has had sufficient vigour to bring life back from the most severe of deadly insults, restoring and maintaining temperatures within life’s comfort zone.
But now Gaia is deathly ill. It is to her that we must direct our attentions. The climate change, over which we now fret, is both symptom and driver of the morbidity. The causative pathogen is us, and if we wish to survive the fate we are beginning to foresee, then we must turn our focus away from us and towards the patient. As in the old chestnut, if it hurts, we must stop doing it.
We must seek to reduce the fever of global warming where we can — just listen to the pathogen talking — but it must be Gaia herself who will effect the cure in the end. We must find ways to be her benign accomplice not her antagonist. First up, we must put the C for Climate Change in its proper place at the end of the HIPPO acronym. This may have some resonance, producing after all the first two sounds in the word hypocrisy, a not unknown quantity in our dealings, political and economic. Take note Bill, Jean and others.
In his recent book Deep Economy, Bill McKibben records that ecological economists have assigned ecosystem services a “worth” of $33 trillion per annum, far larger than that of the entire human economy. In truth, the value of the biosphere is inestimable, even more so than that of human life itself. After all it is Gaia that got us here. It’s time we gave her some generous payback and the loving care she deserves.
I will give the last word to another Earth mother, an admonition for an unrepentant future:
“No witch craft, no enemy action had silenced the rebirth of new life in this stricken world. The people had done it themselves.”
Rachel Carson, Silent Spring.