James Hansen: "The 2C Target Is Dead Because Global Energy Use Is Rising And Will Continue To Rise"

The pace of global heating has been significantly underestimated, according to renowned climate scientist Prof James Hansen, who said the international 2C target is “dead”. A new analysis by Hansen and colleagues concludes that both the impact of recent cuts in sun-blocking shipping pollution, which has raised temperatures, and the sensitivity of the climate to increasing fossil fuels emissions are greater than thought.

The group’s results are at the high end of estimates from mainstream climate science but cannot be ruled out, independent experts said. If correct, they mean even worse extreme weather will come sooner and there is a greater risk of passing global tipping points, such as the collapse of the critical Atlantic ocean currents. Hansen, at Columbia University in the US, sounded the alarm to the general public about climate breakdown in testimony he gave to a UN congressional committee in 1988.

“The Intergovernmental Panel on Climate Change (IPPC) defined a scenario which gives a 50% chance to keep warming under 2C – that scenario is now impossible,” he said. “The 2C target is dead, because the global energy use is rising, and it will continue to rise.” The new analysis said global heating is likely to reach 2C by 2045, unless solar geoengineering is deployed.

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Hansen’s team took a simpler approach, calculating the potential range in temperature rises for a doubling of CO2 and then using data on how much heat the Earth has trapped to estimate the most likely climate sensitivity. Their estimate is 4.5C. Cloud formation, which is affected by global heating and aerosol pollution, is a key source of the uncertainties. Anomalously high temperatures have continued in January 2025, which set a new record for the month and confounded expectations that temperatures would drop with the current La Niña, the cooler part of the El Niño cycle. “This unexpected record may presage higher temperatures this year than many of us thought,” said Hausfather. Hansen’s group also argues that the accelerated global heating they predict will increase ice melting in the Arctic.

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https://www.theguardian.com/environment/2025/feb/04/climate-change-target-of-2c-is-dead-says-renowned-climate-scientist