McGinn said Montana should continue with its incentives to encourage renewable-power development.

Charette, director of the Marine Corps' Expeditionary Energy Office, said the military's reliance on fossil fuel often makes it more vulnerable to enemies.

Marines in Afghanistan must move fuel convoys through Pakistan, for many weeks, he said. For every 50 fuel and water convoys, one Marine is killed or wounded, he said.

To reduce the threat, the Marine Corps has been developing patrols that use renewable energy, such as small, flexible solar systems to power equipment that had been powered by generators, Charette said.

McGinn said he has studied the science on climate change, and is convinced the science is valid.

He said while the issue has become highly politicized, he noted that 95 percent of climate-change scientists believe change is occurring and is caused by man-made greenhouse gases.

"If I'm a Marine captain in Afghanistan and I've got 95 percent of the intel reports telling me there's a likelihood of a Taliban ambush over the pass that I'm going to escort a fuel convoy on, and I've got five percent of those reports that are table-pounding intel saying ‘No problem,' who do you think I'm going to listen to?" he said.