A letter has been sent by California Gov. Jerry Brown to Republican presidential candidate Ben Carson regarding what the retired neurosurgeon has claimed. Carson claims that there is no solid proof that human beings are causing global warming.

Carson talked regarding the matter in an interview with the San Francisco Chronicle that was carried out when he visited The Golden State.

Brown wrote to Carson prior to citing global warming claim by the presidential candidate, "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".

Brown also told Carson that a USB flash drive was also included that is "with the complete United Nations Intergovernmental Panel on Climate Change" (IPCC) report. He said that it is among many studies, which show that climate change is a result of man's actions.

Brown wrote that the results of the study are real. The Democratic governor asked him to use his substantial intelligence for reviewing the material and said that climate change is much larger than politics.

Carson's campaign was asked for comment, but there was no response till the time of publication. On Thursday, Carson received the flash drive that included the proof for climate change that he has been seeking.

The United Nations Environment Program and the World Meteorological Organization has created IPCC.