© It’s the Planet 2008

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Why is biodiversity important?

There have been five mass extinction events in the past, when species losses were huge, synchronous and global in scale.  The last of these occurred about 65 million years ago and wiped out the dinosaurs (except their bird descendants) and at least 70 % of all other species.  For several million years, a period 100 times greater than the entire known history of Homo sapiens, the planet's destroyed ecosystems underwent a slow, laborious recovery.

The evidence shows that species loss today is accelerating.  According to Robert May “we can see we are on the breaking the tip of what will be the sixth great wave in the extinction of life on Earth, differing from the five big previous ones, ... by being deliberately associated with our activities”.  It's taking place, in real time, and this time it is down to us.

In 2007, of 41,415 species assessed for the International Union for the Conservation of Nature (IUCN) Red List of Threatened Species, 16,306 (39 %) were categorized as threatened with extinction: one in three amphibians, one quarter of the world's pines and other coniferous trees, one in eight birds and one in four mammals. Another study identified 595 "centers of imminent extinction" in tropical forests, on islands and in mountainous areas. Disturbingly, only one-third of the sites surveyed were legally protected, and most were surrounded by areas densely populated by humans.

Should our only concern be for the future welfare of ourselves and our children? Assuming that we survive the current mass extinction event, won't we do okay? After all, we could argue that the disappearance of more than a few species is regrettable, but we can't compromise an ever-expanding population and a global economy whose collapse would leave billions to starve. This, however, ignores an essential fact about all those species: they live together in tightly networked ecosystems responsible for providing the habitats and ecosystem services which we need in order to thrive. Pollination of flowers by diverse species of wild bees, wasps, butterflies and other insects, not just managed honeybees, accounts for more than 30 % of all food production that humans depend upon. Our future welfare and the survival of other species are not separate issues but are intimately connected.

As an example, consider the fact that climate change is already threatening us with the spread of infectious diseases, which will move farther north and to higher elevations as temperatures escalate.  While the insects which carry these diseases are proliferating, three quarters of all birds species -- a formidable first line of defence against the threat of disease-carrying insects -- are on the decline. To add to the problem, 26% of bat species are threatened with extinction.  It is estimated that bat colonies in Texas alone eat 250 tons of insects every night.  Are we to increase using pesticides to combat insect pests, causing yet more damage to the world’s animal species and to ourselves?  This would be the price of losing major insect predators.

If we sleep walk into this future of vastly diminished biodiversity, what might it look like?  It is not a pretty picture. The tropics and coral reefs, major sources of the planet's biological diversity, will be hugely debilitated, and the 21st century may mark the end of the line for the evolution of large mammals.  Disrupted ecosystems will provide vacant niches to all those opportunistic invader species that have already demonstrated their capacity to wipe out native plants and animals, and we will find ourselves largely embraced by a pest and weed ecology ideal for the flourishing of invasive species and new, potentially dangerous microbes to which we haven't build up a biological resistance.

The sixth extinction event is under way and we have spectacularly failed so far to recognise that it is not just happening ‘out there’ but will affect all of us.