California’s governor has provided presidential hopeful Dr. Ben Carson with “overwhelming evidence” of climate change, something that the Republican candidate claimed does not exist.

Last week, Carson appeared in San Francisco as part of his campaigning schedule. At an event, he addressed why the "climate change debate" remains, in his view, "irrelevant." In a tweet published later in the week, Gov. Jerry Brown (D) posted a picture of this letter sent to the retired neurosurgeon.

Dear Dr. Carson, I hope you've enjoyed your visit to the Golden State. It's come to my attention that while you were here you said the following regarding climate science: "I know there are a lot of people who say 'overwhelming science,' but then when you ask them to show the overwhelming evidence, they never show it…There is no overwhelming science that the things that are going on are man-caused and not naturally caused. Gimmie a break." Please find enclosed a flash drive with the complete United Nations Intergovernmental Panel on Climate Change (IPCC) "Synthesis Report," the concluding installment of the Fifth Assessment Report, published earlier this year. This report assessed over 30,000 scientific papers and was written by more than 800 scientists, representing 80 countries around the world, who definitively concluded that: "…human influence on the climate system is clear and growing, with impacts observed across all continents and oceans." This is just one of the thousands of reports authored by the world's top scientists on the subject, including a study published just last month by Columbia University, University of Idaho and NASA Goddard Institute for Space Studies scientists that found climate change has intensified California's drought. These aren't just words. The consequences are real. Please use your considerable intelligence to review this material. Climate change is much bigger than partisan politics. Sincerely, Jerry Brown

The Carson campaign did not immediately respond to Ars’ request for comment. As of publishing, the Carson campaign did not appear to have responded to Gov. Brown, either.

The science is indeed clear about climate change's effects on California's drastic drought, which has gone on for four years now. Groundwater overuse during the drought has reached epic proportions, with the land surface in some locations sinking almost two inches per month as a result.