In history, one gathers clues like a detective, tries to present an honest account of what most likely happened, and writes a narrative according to what we know and, where we aren't absolutely sure, what might be most likely to have happened, within the generally accepted rules of evidence and sources.
There has been evidence throughout history of cycles when the earth gets warmer and cycles when the earth gets colder. We should always be wise stewards of the earth and all of our natural resources. But as a policymaker, I won't be guided by the global warming propaganda machine. Al Gore - we need you to return your Nobel Peace Prize!