Green thinking can produce dividends, it seems (Image: Afton Almaraz/Getty)

Environmentalism seems to work.

In the US, states with higher support for the environmental movement have lower carbon emissions, and the strength of these movement over time in each state affects their emissions.

That’s the message from a study looking at the impact of the environmental movement on actual emissions of carbon dioxide in each state from 1990 onwards.


“Our major finding is that states with higher levels of environmentalism have lower emissions than we would otherwise expect,” says Thomas Dietz of Michigan State University in East Lansing, Michigan. “Also, as states become more environmentalist over time, their emissions increase less than you would otherwise expect.”

The dominant factors driving increases in greenhouse gas emissions are population growth and increasing affluence, Dietz says: put simply, when there are more people with more money, consumption of goods and energy rises.

But the study finds that environmentalism is the factor that most strongly counteracts this trend, through people cycling instead of driving, for example, or through adoption of renewable energy sources such as solar, and through stronger enforcement of measures to counter emissions, such as mandatory insulation in homes.

Voting record

As a proxy measure for how strong the environmental movement in each state has been since 1990, Dietz and his colleagues relied on the voting records of members of Congress from each state as rated by the League of Conservation Voters, an environmental group.

“We’re not saying it’s the voting of members of Congress per se that is producing the effect,” he says. “Rather, the voting record is a pretty good indicator of how green the state is.”

They found that even if the main drivers of emissions continue to grow, local environmental movements can substantially counteract them. For example, a 1-per-cent increase in a state’s environmental score more than neutralises typical annual increase in emissions in a state as a result of population growth.

They also ruled out other factors, showing for example that a state’s political allegiance or trade union strength had negligible impacts on emissions compared with environmentalism.

“What we’re showing is that environmentalism, broadly defined, seems to have a substantial effect,” says Dietz. That broad definition encompasses not just the existence of campaigning organisations but also which policies are adopted, how strictly regulations are enforced and how companies and individual consumers may be acting voluntarily to cut emissions.

But not everyone is convinced. “Inferring public opinion in a state from the voting behaviour of elected representatives in the US Congress is, in my opinion, unfounded,” says Jon Krosnick of Stanford University in California.

He says the results are not sufficient to conclude that pro-environmental orientations of representatives in the US Congress actually caused reduced greenhouse gas emissions in their states.

Journal reference: PNAS, DOI: 10.1073/pnas.1417806112