Former Gov. Tim Pawlenty's position on climate change has now shifted from "one of the most important issues of our time" to questioning whether humans have had any effect on climate change at all.

In a wide-ranging interview with the Miami Herald, Pawlenty said that "the weight of the evidence is that most of it, maybe all of it, is because of natural causes. But to the extent there is some element of human behavior causing some of it -- that's what the scientific debate is about."

It wasn't too long ago that Pawlenty took a much more muscular approach to climate change. Shortly into his second term as governor, the Minnesota Republican made a big push for clean energy.

When he was named chair of the National Governors Association, Pawlenty had the theme of "Securing a Clean Energy Future." He touted Minnesota legislation that set an ambitious goal of reducing greenhouse gas emissions 15 percent by 2015 and 80 percent by 2050. In 2007 he said he wanted the Upper Midwest to become "the Saudi Arabia of renewable energy."

Pawlenty had teamed up with explorer Will Steger, planning a trip with him to the Arctic before he ultimately canceled. He joined with then-Arizona Gov. Janet Napolitano, a Democrat, in 2008 for an ad sponsored by the Environmental Defense Action Fund that pushed Congress to act on clean-energy standards. At one point, he called U.S. actions on energy "unsustainable" and, in calling for new carbon emission standards, said that "we have an unbelievable and unhealthy amount of our economy hooked to fossil fuels."

At a National Governors Association meeting in February 2008, Pawlenty said, "What you're seeing now is a great momentum and in many ways a bipartisan consensus about the need to make progress in this area."

Pawlenty has since apologized for his support of cap-and-trade and said that his past support of initiatives to slow climate change and limit carbon emissions were "clunkers" in his record. Pawlenty has said that every presidential candidate at one point supported climate change legislation.

At an event with Steger in January 2008, Pawlenty referenced the fact that some people did not believe in climate change. But he said that shouldn't be an excuse not to act.

"Suppose the whole thing is a hoax," Pawlenty said. "The worst thing we'll do in the process is clean up the world and leave a better planet for our children and grandchildren."

Jeremy Herb • 202-408-2723