evidence: Observed Arctic sea ice loss, and mass loss from the Greenland and Antarctic ice sheets, is not explained by natural variability alone. Research indicates that human activity has made a significant contribution to the loss of glacial ice and Arctic sea ice. Read full claim review [...] The statement is definitely false for Arctic sea ice, which is decreasing dramatically since the 1990s as a response to human greenhouse gas emissions. In fact, there is a direct and linear relation between CO2 emitted and sea ice decline: each metric ton CO2 emitted leads to a 3 m2 loss of Arctic sea ice5 . The current loss of sea ice falls outside of natural variability and has been unprecedented in at least the last 1,450 years6. [...] A recent study* suggests that as much as 60 % of the observed loss in late-summer Arctic sea ice extent could have been caused by changes in atmospheric circulation patterns – i.e., natural causes. Natural factors can only explain a part of the observed losses, and multiple studies (reviewed in the latest IPCC report) have shown that it is not possible to explain the observed losses without considering non-natural factors.