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: A 2018 systematic review study estimated that ice loss across the entire continent was 43 gigatons (Gt) per year on average during the period from 1992 to 2002, but has accelerated to an average of 220 Gt per year during the five years from 2012 to 2017.