“Think globally, act locally” makes for a nice bumper sticker — but is it an effective policy for coping with global climate change? Can local actions make a difference in a process principally driven by worldwide trends?

The short answer is “no,” according to the Intergovernmental Panel on Climate Change. We cannot do much locally to lessen the effects of global drivers; therefore, our local policies must focus on adaptation.

There is more to the story, however, according to Charles Perrings, a professor of environmental economics at Arizona State University. While it is true that there is little to be done locally to affect global causes, Perrings says, there is quite a bit to be done to lessen the effects of climate change in our own backyards. The trick is to work locally to diversify our ecosystems to make them more resilient for what is to come.

Perrings’ argument, which he will present Feb. 17 at the American Association for the Advancement of Science annual meeting, is based upon the findings of the 2005 United Nations’ Millennium Ecosystem Assessment (MA). Like the IPCC report, the MA is a comprehensive synthesis of existing information, scientific literature and data; but whereas the IPCC report discusses climate change generally, the MA focuses on improving ecosystem management and human well-being.

“The MA points to the value of regulating ecosystems locally to function over a range of environmental conditions,” Perrings says. “The challenge now is to deepen our understanding of diversity’s impact on both the supply of valued goods and the severity of harmful events.”

Understanding the value of ecosystem change is one more tile in the global climate change mosaic, one that, according to Perrings, scientists and policymakers must understand if they are to accurately assess costs and benefits of proposed actions, track ecological assets and develop means of remedying the problem.

“The vulnerability of many communities depends on local ecosystem structure and local biodiversity,” Perrings says.