Energy Secretary Steven Chu said Wednesday that scientific evidence of climate change is getting more and more powerful, comments that come as global warming legislation remains moribund in Congress and Environmental Protection Agency regulations are facing ongoing GOP assaults.

“Over the last couple of years, the dispassionate, hard science evidence has been mounting, increasing,” said Chu, speaking at an energy forum hosted by The New York Times.

Chu noted that “we don’t understand everything” and that in past years scientists have actually underestimated the pace of some changes, including sea level rise.

{mosads}“It is rising even faster than we thought. The number of violent rainstorms have increased faster than we thought,” he said at the event in New York, adding that though there are “bumps and wiggles” that are not understood, trends are clear in the long term.

“The debate is how much will it change. There are feedbacks both positive and negative that we are trying to understand,” said Chu, a Nobel Prize-winning physicist.

The vast majority of scientists say global warming is occurring and human activities are a key factor. A small minority call data on warming trends and the human contribution inconclusive or inaccurate.

That skepticism has become a mainstream position among Republicans, who also argue that regulations to curb climate change are unnecessary and would be economically harmful.

But climate aside, Chu said there’s a powerful economic case for the United States supporting the development of renewable energy sources and industries, noting that “the world is going in this direction.”

“Don’t you want to be selling rather than buying? You don’t even have to think about [climate] to say there are new technologies coming. It is our lead to lose. We are still the greatest innovative country in the world and here is a worldwide market that is going to grow and grow and grow,” he said.

Chu’s comments come at a sensitive time for the Energy Department, which is under heavy GOP attack over the 2011 bankruptcy of Solyndra, the California solar panel company that had received a $535 million loan guarantee in 2009.

The administration plans to proceed with more loan guarantees, but other green-energy programs and EPA rules face hurdles.

For instance, tax credits for renewable power projects are slated to lapse at year’s end and their renewal is a question mark.

And a stimulus-law program that provided Treasury Department grants in lieu of tax credits for such projects — a response to the collapse of the tax financing market during the financial downturn — has expired despite administration efforts to extend it.

Chu said he was hopeful the failure of Solyndra — which Republicans have used as the basis for wider criticisms of Energy Department loan programs — won’t sap support for efforts to spur green-energy innovation.

“I hope the United States does not lose its appetite for moving forward,” Chu said in the interview with Times columnist Tom Friedman.

He noted that the loan guarantee program was designed with some risk in mind, and that Congress appropriated billions of dollars to cover potential losses.

“I think some people forgot that that was the design of the program,” he said, adding that setbacks are unfortunate but that many of the loans and loan guarantees are performing well.

He said the roughly $6 billion loan provided to Ford Motor Co. preserved and created jobs, and noted that many of the loan guarantees have been for renewable power projects, including ones that have agreements with utilities to purchase their power.

“We think those are fairly safe loans,” he said. Loan guarantees for manufacturers like Solyndra have been much fewer in number.

However, some other companies supported by Energy Department loan guarantees or grants have faced financial problems as well.

Referring to support for green energy broadly, Chu said the goal is to back emerging technologies that will reach wide commercial adoption without long-term federal support.

There should instead be “short-leash” subsidies, perhaps in the 10-year range, he said, and that the private sector must be confident a technology can survive without subsidy.

“We want to create self-sustaining entities,” Chu said.

While lawmakers are battling over various types of green energy support, it has been Solyndra and the loan guarantee program that has placed Chu in the hotseat on Capitol Hill.

Asked what he has learned from Solyndra specifically, Chu sighed audibly.

“Many things,” he told Friedman. “I can tell you over a beer.”