| 0.6 +/- 0.2°C warming observed during 20th Century SupportiveArgument1 #5042 The Earth’s globally averaged surface temperature rose by approximately 1.08°F (0.6°C +/- 0.2°C) during the 20th century. |
Source: IPPC Working Group I: The Scientific Basis (2001), Chapter 2"The best estimate of global surface temperature change is a 0.6°C increase since the late 19th century with a 95% confidence interval of 0.4 to 0.8°C." |