Population and nature – the human implications

Aaron Bernstein, Science Alert 13 Apr 10;

The population debate has heated up in Australia for many very good reasons, but one of those reasons, which in its own right has serious implications, is not getting much attention. While we - as a species of this planet - may squeeze through the current population-climate bottleneck, others may not. Treasury are now predicting Australia’s population will swell to 36 million by 2050 and globally, a massive human population is estimated to peak at 9 billion people. Combined with climate change, this population increase will conspire to exert a tremendous strain upon the planet. Unless unchecked, the continued increase of our numbers on the planet is more than likely to result in serious consequences for human health and we risk placing short-term advantage over long-term gain at our own peril.

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 variety 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. Here in Australia, many scientists 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, overharvesting (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.

Underlying all these causes rests an already unwieldy and growing human population. What does this vast simplification of the biosphere cost us? Not much based on our current accounting practices. That would be a fair value if not for it deriving 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.

Particularly for antibiotics and cancer treatments we rely upon nature for inspiration. Want a dose of Tamiflu(r) to treat your H1N1? Or vancomycin to treat methicillin resistant Staphylococcus aureus or MRSA (vancomycin is one of our last lines of defense against this superbug)? You'd be out of luck without the Chinese star anise tree and a bacteria 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 hold infectious diseases at bay - the emergence of SARS and Nipah virus can be pinned on human activities that altered ecosystems - or that are needed for productive agriculture. 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 takes me back 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 well-being, 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 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 lacking 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, at least on some level, with it.

Dr Aaron Bernstein is on faculty at Harvard Medical School and its Center for Health and the Global Environment. He practises paediatrics at Children’s Hospital Boston. Along with Nobel Peace Prize recipient Eric Chivian, he co-authored the Oxford University Press book “Sustaining Life: How Human Health Depends on Biodiversity”. The book has been widely acclaimed, including by Al Gore, Kofi Annan, and Gro Brundtland.

He is giving a National Press Club address on Tuesday, 13 April titled “Biodiversity Loss and the Climate-Population Bottleneck”.

Dr Aaron Bernstein’s speaking tour has been made possible thanks to the Thomas Foundation Conservation Oration presented in partnership with The Nature Conservancy.