What's biodiversity worth?

G Magazine

Over the next two weeks, the fate of the 17-year old U.N. Convention on Biological Diversity is being discussed by world officials in Nagoya, Japan. But why does our future wellbeing depend so heavily on biological diversity?

Biodiversity is in our hands

The emergence of SARS and the Nipah virus can be pinned on human activities that altered ecosystems.

Credit: iStockphoto

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The population debate has heated up in Australia for many very good reasons, but one of those is not getting much attention. Population is a hot topic at the moment, but while we, as a species, may squeeze through the current population-climate bottleneck, others may not. And this could lead to devastating results for our planet.

The only truly irreversible consequence of environmental degradation, whatever the cause, is a loss of biological diversity, namely the variety of life on Earth. Once a gene, species or ecosystem disappears, it is gone forever. It's no secret that biodiversity, a word that encapsulates the diversity of life - from individual species, to the genes they possess and the ecosystems they form - is disappearing. A conservative estimate puts the pace of species extinctions today on par with 65 million years ago when 50 per cent of all species went extinct, including the dinosaurs.

Many scientists here predict that Northern Australia is facing a new and potentially catastrophic wave of mammal extinctions. Some unique species to Australia have already disappeared from more than 90 per cent of their past range and many formerly abundant animals such as the northern quoll, golden bandicoot and bilby are declining, and doing so very rapidly. The declines are being reported from pastoral lands, indigenous lands and national parks alike.

Pollution, over-harvesting (especially of seafood) and invasive species all contribute to biodiversity loss, but the lion's share of the problem at present owes to the degradation or outright destruction of habitats on land, in freshwater bodies or at sea. At mid-century, climate change will likely overtake habitat loss as the leading driver of species extinction.

Underlying all these causes rests an already unwieldy and growing human population. What does this domination of the biosphere cost us? Not much based on our current accounting practices. That would be a fair value if it were not derived from a dangerous delusion - perhaps the most dangerous of our time - that somehow we can wipe out vast swaths of the living world without that loss affecting ourselves.

For antibiotics and cancer treatments in particular, we rely upon nature for inspiration. Want a dose of Tamiflu to treat your H1N1? Or vancomycin to treat methicillin-resistant Staphylococcus aureus (MRSA), one of our last lines of defence against this superbug? You'd be out of luck if not for the Chinese star anise tree and a bacterium known as Amycolatopsis orientalis.

We may lose new blockbuster drugs as we lose species, but this loss is, among the other value that biodiversity holds, comparatively small. More costly has been the dismantling of ecosystems, such as those that are needed for productive agriculture or that hold infectious diseases at bay - the emergence of SARS and the Nipah virus can be pinned on human activities that altered ecosystems. Topsoil erosion, the loss of pollinators, and the spread of crop pests and pathogens all relate to lapses in sound management of our natural capital.

And that comes to the ledger. If we are to find our way to sustainability, we need to have a better accounting of the value of nature's services to our own wellbeing, a task that scientists and economists have just begun to grapple with. Costing out the value of lost species to pharmaceutical development or scientific progress (much of biomedical science depends on insights or materials provided from nature) is relatively straightforward, although valuing what we only know comes to perhaps 1 in 10 of all species. More daunting will be sorting out how changes to local ecosystems, even in the absence of outright species extinctions, may degrade our quality of life. Until we have this knowledge at hand, it will be next to impossible to have a balanced nature budget.

But even before we can start valuing nature and its services, we may have another bridge to cross. What has enabled our poor accounting has been the gradual erosion of our relationship with nature. Most humans, and particularly those living in the developed world and in cities, have literally lost sight of nature and lack a direct attachment to it. Discovering how damage to the biosphere may harm humanity becomes a still taller order.

To ensure the healthiest possible future, then, we must also find ways to relearn that we have a vital bond with nature and that ultimately, we share a common fate with it.

Dr Aaron Bernstein is from the Centre for Health and the Global Environment at Harvard Medical School. Along with Nobel Peace Prize recipient Dr Eric Chivian, he co-authored the Oxford University Press book Sustaining Life: How Human Health Depends on Biodiversity.