claim: But we do have other reliable indicators of temperatures before the late 1800s, and the evidence shows temperatures have been warmer than today for most of the past several thousand years, including warmer-than-present temperatures for most of the human civilization time period
evidence: It is likely that anthropogenic (i.e., human-induced) warming, such as that due to elevated greenhouse gas levels, has had a discernible influence on many physical and biological systems.