New research suggests that environmental activism is more effective than most people think.

Researchers at Michigan State University found that the environmental movement is making a difference -- nudging greenhouse gas emissions down in states with strong green voices.

"We've used new methods developed over the years and new innovations Ken has developed to add in the politics - and find that politics and environmentalism can mediate some environmental impact," researcher Thomas Dietz said in a statement. "Environmentalism seems to influence policies and how well policies that are in place are actually implemented and it also influences individual behavior and the choices people make."

For the study, researchers compared greenhouse gas emissions between all the U.S. states and within each state over time going back to 1990, and determined how emissions correlated with population, gross state product per capita, employment rate, and environmentalism.

They found that a 1 percent increase in environmental activism correlated with reduced emission -- more than enough to compensate for the typical annual increase in emissions.

"Efforts to mitigate emissions take a variety of forms at the state and local level and may have substantial impact even in the absence of a unified national policy,"researchers noted. "Existing regulations can be applied strictly or less stringently, and programs can be pursued enthusiastically or given a low priority. Even without formal policy and programs, the importance of reducing emissions can be widely accepted by individuals and organizations and result in actions that have substantial impact."

Researchers said their findings offer a new way of understanding what drives humans' impact on the environment, one that both see as a first step at turning up the sensitivity of understanding how people are players in the environment's health.

The findings are detailed in this week's Proceedings of the National Academy of Sciences.