claim: Fourth Assessment Report ( AR4 ), in which the likely range is given as 2.0°C to 4.5°C, with a best estimate of 3.0°C ( Pat Michaels )
evidence: IPCC authors concluded ECS is very likely to be greater than 1.5 °C ( 2.7 °F ) and likely to lie in the range 2 to 4.5 °C ( 4 to 8.1 °F ), with a most likely value of about 3 °C ( 5 °F ).