Story highlights Jeb Bush says it's not clear what percentage of climate change is man-made

He says government should provide incentives for methods like hydraulic fracking and horizontal drilling

Bedford, New Hampshire (CNN) Jeb Bush hit back against President Obama's claim that climate change runs an immediate risk, saying Wednesday that while it shouldn't be ignored, it's still not "the highest priority."

As he has before, Bush acknowledged "the climate is changing" but stressed that it's unknown why. "I don't think the science is clear of what percentage is man-made and what percentage is natural. It's convoluted," he said at a house party in Bedford, New Hampshire.

"For the people to say the science is decided on this is really arrogant, to be honest with you," he continued. "It's this intellectual arrogance that now you can't have a conversation about it, even. The climate is changing. We need to adapt to that reality."

Earlier Wednesday, Obama warned in a commencement speech to the U.S. Coast Guard Academy that climate change "constitutes a serious threat to global security (and) an immediate risk to our national security."

Shaking his head as the host of the house party, Richard Ashooh, quoted Obama's remarks, Bush chided the President for taking what he argued was the wrong path in addressing the problem.

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