California governor challenges GOP candidates on climate change

Democrats are also looking forward to Thursday's debate among the Republican presidential candidates -- and making demands.

California Gov. Jerry Brown, for example, released an open letter Wednesday asking the GOP candidates what they plan to do about climate change.

“Longer fire seasons, extreme weather and severe droughts aren’t on the horizon, they’re all here -- and here to stay," Brown said in his letter. "This is the new normal. The climate is changing. Given the challenge and the stakes, my question for you is simple: What are you going to do about it? What is your plan to deal with the threat of climate change?”

The GOP candidates gather Thursday in Cleveland.

In general, the Republicans have criticized President Obama's climate change plans as government overreach that will cut jobs in the energy sector and increase utility bills for middle class Americans.