Stephan Harding (British, born 1953) holds a doctorate in behavioral ecology from the University of Oxford. He is currently head of the master’s in holistic science program at Schumacher College, Dartington, Devon, UK. He is author of Animate Earth: Science Intuition and Gaia, and the presenter of a documentary film of the same name.
Biodiversity is the diversity of life at various levels of organisation, ranging from genes to species, ecosystems, biomes, and landscapes. As far as we can tell, the earth just before the appearance of modern humans was the most biodiverse it has ever been during the 3.5 billion years of life’s tenure on this planet, and before we began to upset things it hosted a total of somewhere between 10 million and 100 million species.The fossil record shows us that there have been five mass extinctions in the last 400 million years or so, all due to natural causes such as meteorite impacts or flood basalt events, or possibly because of drastic internal reorganizations within biotic communities, but the greatest and fastest mass extinction is happening now and is entirely due to the economic activities of modern industrial societies.
We are currently hemorrhaging species at a rate up to 1,000 times the natural rate of extinction, or, more prosaically, every day we are losing a hundred species, mostly in the great tropical forests because of our endless desires for timber, soya, palm oil, and beef. Coral reefs and the marine realm in general are not exempt from our destructive attentions—they too are experiencing catastrophic species declines.
The list of atrocities that our culture has perpetrated on the living world makes for chilling reading. We could have eliminated a quarter of all the organisms on the Earth by 2052. Even by the year 2000, about 11% of all bird species, 18% of mammals, 7% of fish, and 8% of all the world’s plants were threatened with extinction.
According to the Living Planet Index, in the period from 1970 to 2000, the population sizes of forest species declined by 15%, those of freshwater species by a staggering 54%, and those of marine species by 35%. By 2052, we may well have increased the overall rate of species extinctions to around 10,000 times the natural background rate.
The plight of biodiversity in the modern world came home to me recently when I took my nine-year-old son on a visit to our local zoo. What we found there epitomizes the likely relationship between humans and the rest of the biological world in 2052. A sea of humans obsessed with mobile phones, cameras, and a whole plethora of planet-destroying consumer goods seethed and swarmed in a pulsing, chattering crowd around small islands of carefully managed artificial habitat, each containing an exotic species either doomed to extinction or under heavy stress in its dwindling wild home.
The world in 2052 will be a zoo writ large, only far worse, for by then we will have reduced all of the planet’s once vast, unbroken terrestrial ecosystems to tiny islands of habitat surrounded by agribusiness fields crisscrossed with roads, pylons, and sprawling cities, while climate change will have made a great deal of the planet almost uninhabitable for most species, including ourselves, owing to extreme weather events and sea-level rise.
The major drivers of the mass extinction will, by 2052, have revealed themselves far more evidently than they do today. Perhaps the most visible of them all is the destruction and fragmentation of habitats, which I think by then will have laid waste to all of the world’s wild places, most notably the tropical rain forests, which will survive only as a few pitifully small and severely degraded remnants within national parks and reserves.
Another major driver of the mass extinction is the introduction of exotic species, which by 2052 may well have wiped out more species than some of the other major drivers, such as pollution, human population pressures, and overharvesting. Even by 2006, about 4,000 exotic plant species and 2,300 exotic animal species brought to the United States alone had threatened 42% of species on the endangered species list, causing about $138 billion of damage in sectors such as forestry, agriculture, and fisheries.
But perhaps the most pernicious of all the drivers of the mass extinction will have become well entrenched by 2052. I refer of course to climate change. By 2052 the planet will have warmed by 2°C and possibly more, with many disastrous consequences both for humans and for our planet’s biodiversity. One such effect could be the irreversible dieback through wildfires of the Amazon forest. The carbon dioxide released into the atmosphere from such burning could increase the warming to 10°C by the end of the century, a pace more rapid than any other previous episode of natural warming.
Climate change will force species out of their home ranges in search of new habitats. Each species has its own very specific range of tolerance for temperature and moisture, and species are even now moving in an attempt to live within their climatological comfort zones as the climate changes around them. The general trend in a 2003 study of 1,700 species is a poleward movement of 6 kilometres per decade, and a 6-meter-per-decade movement up the sides of mountains.
Virtually the whole biosphere is being uprooted in unprecedented ways. Examples are legion, including the northward march of the boreal forest at the expense of open tundra vegetation; the northward expansion of red foxes in Arctic Canada and the simultaneous shrinking in the range of the arctic fox; the upward movements of alpine plants in the European Alps by 1 to 4 meters per decade; the increasing abundance of warm-water species among the zooplankton, fish, and intertidal invertebrates in the North Atlantic and along the coasts of California; and the extension of lowland Costa Rican birds into higher areas from lower mountain slopes because of changes in the frequency of dry-season mist. By 2006 in Britain and North America thirty-nine butterfly species had moved northward by up to 200 kilometers in twenty-seven years.
By 2052, many terrestrial species will have died out, as the changing climate obliged them to find new homes, yet their forced migrations were made impossible by the severe fragmentation of habitats. In the marine realm, huge numbers of cold-adapted species will have died out in the high latitudes, leaving precious little space for poleward migrating species from the far vaster tropical and subtropical oceans. Ocean acidification—a direct result of the additional carbon dioxide in the atmosphere—will have killed off many species that secrete calcium carbonate in their body parts, such as the corals and coccolithophorid marine algae. Many of these species play essential roles in climate regulation by sequestering carbon and by seeding planet-cooling clouds, so their demise will further warm the earth.
By 2052 ecosystems globally will have been literally torn apart by climate change as the delicate synchronization of events within them is disrupted. The once carefully ordered sequencings of leaf burst, caterpillar emergence, chick hatching, and so on will no longer mesh together as seamlessly as they did, and so these “phenological decouplings” will lead to further collapses of biodiversity in some ecosystems. Since biodiversity is intimately connected to the effectiveness of vital ecosystem functions such as nutrient cycling, water flow regulation, and climate modulation, these losses will make ecosystems less resilient—far less able to buffer the changes thrust upon them by climate change and habitat fragmentation. As a result, by 2052 some land masses in the low and mid latitudes will be well on the way to becoming inhospitable deserts or semideserts.
By 2052, biodiversity loss will have made life very difficult for billions of people who rely directly on the ecosystems around them for their well-being. And those privileged humans in the “developed” world—the people my son and I joined in the zoo that day—what of them? They will also suffer from the consequences of climate change and biodiversity loss, but by 2052 it is possible that technology will have shielded them, for a while at least, from the worst effects. Perhaps for them the initial consequences of the mass extinction will be an immense psychological diminishment—for the wild animals, both large and small, that molded the human psyche with their awesome presences since the dawn of our species will by then have become nothing more than flattened images on those scintillating screens that so fatally disconnect us from the world of nature.