California governor challenges GOP candidates on climate change
California Governor Jerry Brown speaks during a news conference in San Francisco, on Jan. 17, 2014 (AFP Photo/Justin Sullivan)

Democratic California Governor Jerry Brown on Wednesday sent a letter to all Republican presidential candidates pressing them to discuss their plans to deal with climate change.

The letter, sent a day ahead of the Republican primary debate in Cleveland, attributed California's raging wildfires and years-long drought to global warming caused by human activity, a theory generally rejected by the Republican Party.

"Longer fire seasons, extreme weather and severe droughts aren't on the horizon, they're all here - and here to stay," Brown said. "Given the challenge and the stakes, my question for you is simple: What are you going to do about it?"

Brown recently enacted an aggressive plan to cut California's greenhouse gas emissions 40 percent by 2030.

Last month, he urged governors and mayors at a Vatican conference to "fight the propaganda" of big business interests that deny that climate change is human induced.