On June 23, 1988, [James E. Hansen], the NASA scientist testified before the Senate Committee on Energy and Natural Resources. He expressed to the senators his high degree of confidence in a cause-and-effect relationship between the greenhouse effect and observed warming. Mr. Hansens testimony described three possible scenarios for the future of carbon dioxide emissions. He called Scenario A business as usual, as it maintained the accelerating emissions growth typical of the 1970s and 80s. This scenario predicted the earth would warm 1 degree Celsius by 2018. Scenario B set emissions lower, rising at the same rate today as in 1988. Mr. Hansen called this outcome the most plausible, and predicted it would lead to about 0.7 degree of warming by this year. He added a final projection, Scenario C, which he deemed highly unlikely: constant emissions beginning in 2000. Thirty years of data have been collected since Mr. Hansen outlined his scenarios. And the winner is Scenario C. Global surface temperature has not increased significantly since 2000, discounting the larger-than-usual El Nio of 2015-16. It isnt just Mr. Hansen who got it wrong. Models devised by the United Nations Intergovernmental Panel on Climate Change have, on average, predicted about twice as much warming as has been observed since global satellite temperature monitoring began 40 years ago.