IMAGINE a solar-powered machine that filters water, moderates air temperature and regulates the climate. Some would call it an amazing feat of engineering genius. Most people call it a tree.
Humans have a history of overlooking the many ways by which nature supports us. In North America, pollinators are responsible for one in every three mouthfuls of food, yet we are allowing habitat decline and pesticide use to devastate their numbers. Ten per cent of the world's fish catch comes from coral reefs, yet overfishing, pollution and sedimentation have destroyed or degraded one-third of these underwater gardens.
When it comes to sustaining biodiversity, our track record is not very good.
By 2010, the International Year of Biological Diversity, we were to have seen a significant reduction in global rates of biodiversity loss. This target was adopted in 2002 by the signatories to the Convention on Biological Diversity (CBD). But there has been little progress, and CBD officials concede that "most of the direct drivers of biodiversity loss are projected to remain constant or to increase in the near future."
A substantial barrier to progress has been pervasive ignorance of our economic, social and biophysical dependence on biodiversity. If there is any light on the biodiversity horizon, it is that now people seem to better understand that biodiversity is crucial to our well-being.
More often than not, biodiversity is considered to be a matter of protecting endangered species, especially polar bears, whooping cranes and other media darlings. This is how diversity is treated in the best-known monitoring programs and in most species-at-risk legislation. In contrast, modern science and the CBD recognize three aspects of biodiversity: diversity among species; genetic variations within individuals and populations; and ecosystem diversity, which includes the ways organisms interact with each other and the non-living world around them.
Each aspect of biodiversity facilitates the functioning of an ecosystem. In Canada's boreal forest, for example, species diversity builds resilience to disease and invasive plants. Genetic variation gives forest species the capacity to adapt to changing environmental conditions. These, in turn, combine with the cumulative interactions of forest plants, animals, air and soil to produce the air we breathe, filter the water we drink and absorb the carbon we produce in order to mitigate the impacts of global warming. If the boreal forest is to continue providing these essential "ecosystem services," it requires diversity of species, genetics and ecosystems.
Diverse, natural forests are especially good at delivering ecosystem services. But while a tree plantation may produce timber, paper, biofuel and other commodities, its marginal biodiversity limits disease resistance, soil production and, ultimately, its ability to sustain production over the long term.
Shahid Naeem, professor of Ecology at Columbia University, studies the role of biodiversity in ecosystem functioning. "The greater the biodiversity one finds in forests, farms, fisheries, parks and even urban ecosystems," says Naeem, "the more services they will provide and the more resilient they will be to environmental challenges such as global warming, fires and floods." In other words, he adds, "the more diverse our world, the more productive and stable it will be."
This understanding of biodiversity is the central idea behind the CBD. Ratified by 193 countries at the Rio Earth Summit in 1992, the CBD aimed not just at species preservation, but also at biodiversity protection for the survival of all life, and the adoption of more sustainable approaches to resource management and use.
Unfortunately, drafting the accord was the easy part. "In reality, international environmental instruments all tend to be non-binding," explains Eleanor Sterling, director of the Center for Biodiversity and Conservation at the American Museum of Natural History. …