科学美国人60秒:Human Health Depends on a Healthy Environment

What is the value of an intact rainforest? From a people perspective, maybe it's more useful turned into lumber and cropland.

The responses to such arguments have often cited what are called ecosystem services. These are the keys to life that natural systems provide for free—think: breathable air and potable water. Other counters point to the psychological benefits of the natural world. Now we have a new reason for conservation: human health.

Turns out forest fires set to clear land in Indonesia generate the kind of soot that lodges in lungs and shortens lives across Southeast Asia. Dams and irrigation projects upriver in Africa increase the population of malarial mosquitoes downriver. These are just two of the examples from a new analysis in Proceedings of the National Academy of Sciences.

Then consider big upheavals like global warming. Climate change means more deadly heat waves, allergies, infectious diseases and, potentially, a breakdown in food supplies. All obviously bad for human health.

Our understanding of these complex interactions is incomplete. For example, a given forest clearing may be good for some people's well-being but not others, both now and in the future. A better understanding of nature’s value will probably prove vital for human health in the 21st century.

—David Biello