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James Hansen

person · Climate scientist; former director, NASA GISSCredibility: 71%

Why this score? Former director of NASA GISS; his 1988 Senate-testimony scenarios were an early quantified warming forecast largely borne out. Later solo claims (sea-level rise rates, policy prognoses) have at times run ahead of assessed consensus - score each claim on its own record.

Tracked Statements (1)

The earth is warmer in 1988 than at any time in the history of instrumental measurements... With about 99 percent confidence we can state that the warming during this time period is a real warming trend... In my opinion, the greenhouse effect has been detected, and it is changing our climate now.±

— James Hansen · Jun 23, 1988
Context: Detection vindicated: the 1980s warming was real and human-caused, as every later assessment confirmed. His intermediate Scenario B ran a little hot — observed warming tracked close to but somewhat below it, about 30% slower over 1970–2016 than Scenario B projected, mainly because the model's 4.2°C sensitivity was high and the halocarbons it assumed kept growing were later cut by the Montreal Protocol (Carbon Brief/Hausfather).