President Donald Trump's announcement on Thursday that the U.S. will withdraw from the Paris Climate Agreement phases out U.S. commitments to achieve carbon reduction targets and make financial contributions to slow climate change.

It was a move environmentalists found disappointing, at best. But Vanderbilt University law and earth science professors contend initiatives that reduce carbon emissions from corporations and households can fill some of the gap.

They point to the example of Walmart, which reduced carbon emissions worldwide by more than 20 million metric tons by focusing on efficiency in its global supply chain. Google agreed to locate its massive data center in Clarksville, Tennessee, only after the Tennessee Valley Authority agreed to supply it with renewable power.

“There are a billion tons per year of additional emissions reductions that could be achieved over the next decade from private sector action,” said Michael Vandenbergh, the David Daniels Allen Distinguished Professor of Law. “I don't use the word ‘voluntary’ because sometimes the reductions are in response to pressures from an investor or a major customer.”

Vandenbergh serves as director of Vanderbilt's Climate Change Research Network, which includes affiliates from schools and departments across the university. He and others in the network said they saw huge potential for studying the role of corporate and human behavior and of messaging in energy policy.

Often, Americans who resist fixes to climate change are motivated by concern about the fact the fixes involve government regulation, their research shows.

“Almost everybody looking at what to do about climate change assumes it has to be fixed with policies coming from national or international government,” said Jonathan Gilligan, associate professor of earth and environmental sciences. “Those climate responses are important, but let's get real here. Congress isn't going to pass any major bill to restrict carbon dioxide in the near future. The private sector is beginning to realize that the rest of us must do our part.”

Their research also looks at getting individuals to modify simple behaviors—for instance, understanding that many Americans believe myths about the benefits of idling their cars, leading them to waste money and emit additional air pollution. Vandenbergh and Gilligan won the Morrison Prize for the most effective sustainability-related legal academic article published in North America last year.

Vandenbergh and post-doctoral social psychology researcher Alexander Maki recently finished an online study that showed conservative Americans—the least likely to support policy to slow climate change—are more open to reducing carbon emissions when policies are presented through the lens of private governance.

Participants first were asked what they thought about private governance and federal policies surrounding climate change. Then they were randomized and asked to read about a public cap and trade policy, federal regulations or private climate governance. After reading about one of the policy approaches, they again reported their policy views.

“We found that those who read about private governance were the most likely to support private governance approaches,” Maki said. “But we saw particularly large increases in support among conservatives, and this support for private climate governance led them also to support efforts to reduce carbon emissions.

“We started the study with the concern that increasing support for private governance approaches may make people feel like there is not a need for federal intervention, but we didn't find the message about private governance decreased support for federal policies targeting climate change, even among conservatives.”