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Improved knowledge of glacial-to-interglacial global temperature change implies that fast-feedback equilibrium climate sensitivity (ECS) is 1.2 +/- 0.3°C (2$σ$) per W/m$^2$. Consistent analysis of temperature over the full Cenozoic era -- including "slow" feedbacks by ice sheets and trace...

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Bibliographic Details
Main Authors: Hansen, James E., Sato, Makiko, Simons, Leon, Nazarenko, Larissa S., Sangha, Isabelle, von Schuckmann, Karina, Loeb, Norman G., Osman, Matthew B., Jin, Qinjian, Kharecha, Pushker, Tselioudis, George, Jeong, Eunbi, Lacis, Andrew, Ruedy, Reto, Russell, Gary, Cao, Junji, Li, Jing
Format: Report
Language:unknown
Published: arXiv 2022
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Online Access:https://dx.doi.org/10.48550/arxiv.2212.04474
https://arxiv.org/abs/2212.04474
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Summary:Improved knowledge of glacial-to-interglacial global temperature change implies that fast-feedback equilibrium climate sensitivity (ECS) is 1.2 +/- 0.3°C (2$σ$) per W/m$^2$. Consistent analysis of temperature over the full Cenozoic era -- including "slow" feedbacks by ice sheets and trace gases -- supports this ECS and implies that CO$_2$ was about 300 ppm in the Pliocene and 400 ppm at transition to a nearly ice-free planet, thus exposing unrealistic lethargy of ice sheet models. Equilibrium global warming including slow feedbacks for today's human-made greenhouse gas (GHG) climate forcing (4.1 W/m$^2$) is 10°C, reduced to 8°C by today's aerosols. Decline of aerosol emissions since 2010 should increase the 1970-2010 global warming rate of 0.18°C per decade to a post-2010 rate of at least 0.27°C per decade. Under the current geopolitical approach to GHG emissions, global warming will likely pierce the 1.5°C ceiling in the 2020s and 2°C before 2050. Impacts on people and nature will accelerate as global ... : 62 pages, 39 figures, 1 table. Revision for journal resubmission ...