evidence: According to the IPCC, our planet’s actual climate sensitivity is unlikely to be as large as these models suggest, which raises the question of why we would use them if their climate sensitivities are likely unrealistic. Climate sensitivity describes how much global temperatures will rise in response to human-caused greenhouse gas emissions. The best estimate is 3°C of warming for a doubling of pre-industrial carbon dioxide levels, with a likely range of 2.5 to 4°C, but ongoing research aims to narrow this range. [...] Models with a middle-of-the-road climate sensitivity near 3°C often better reproduce the temperature variations of this historical period than those with a large climate sensitivity.