Former Gov. Tim Pawlenty's position on climate change has now shifted from "one of the most important issues of our time" to "most of it, maybe all of it, is because of natural causes."

In a wide-ranging interview with the Miami Herald, Pawlenty questioned whether humans have had any effect on climate change.

"The weight of the evidence is that most of it, maybe all of it, is because of natural causes," Pawlenty said. "But to the extent there is some element of human behavior causing some of it — that's what the scientific debate is about."

He continued: "I think it's fair to say that, as to whether and how much — if any — is attributable to human behavior, there's dispute and controversy over it."

Pawlenty has not always taken this attitude toward climate change, of course. 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's theme was "Securing a Clean Energy Future." He touted Minnesota legislation that set a goal of reducing greenhouse gas emissions 15 percent by 2015 and 80 percent by 2050. He said in 2007 that 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 cancelled. Pawlenty participated in an ad with then-Arizona Gov. Janet Napolitano in 2008 sponsored by the Environmental Defense Action Fund.

"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 said in February 2008 at a National Governors Association meeting.

Pawlenty explains that his past support of initiatives to slow climate change and for cap-and-trade 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."