Global warming in the pipeline
Authors: James E. Hansen (Climate Science, Awareness and Solutions, Columbia University Earth Institute, New York, NY, USA), Makiko Sato (Climate Science, Awareness and Solutions, Columbia University Earth Institute, New York, NY, USA), Leon Simons (The Club of Rome Netherlands, 's-Hertogenbosch, The Netherlands), Larissa S. Nazarenko (NASA Goddard Institute for Space Studies, New York, NY, USA), Karina von Schuckmann (Mercator Ocean International, Ramonville St.-Agne, France), Norman G. Loeb (NASA Langley Research Center, Hampton, VA, USA), Matthew B. Osman (Department of Geosciences, University of Arizona, Tucson, AZ, USA), Pushker Kharecha (Climate Science, Awareness and Solutions, Columbia University Earth Institute, New York, NY, USA), Qinjian Jin (Department of Geography and Atmospheric Science, University of Kansas, Lawrence, KS, USA), George Tselioudis (NASA Goddard Institute for Space Studies, New York, NY, USA), Andrew Lacis (NASA Goddard Institute for Space Studies, New York, NY, USA), Reto Ruedy (NASA Goddard Institute for Space Studies, New York, NY, USA), Gary Russell (NASA Goddard Institute for Space Studies, New York, NY, USA), Junji Cao (Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China), Jing Li (Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing, China)
Abstract: Improved knowledge of glacial-to-interglacial global temperature change implies that fast-feedback equilibrium climate sensitivity is at least ~4{\deg}C for doubled CO2 (2xCO2), with likely range 3.5-5.5{\deg}C. Greenhouse gas (GHG) climate forcing is 4.1 W/m2 larger in 2021 than in 1750, equivalent to 2xCO2 forcing. Global warming in the pipeline is greater than prior estimates. Eventual global warming due to today's GHG forcing alone -- after slow feedbacks operate -- is about 10{\deg}C. Human-made aerosols are a major climate forcing, mainly via their effect on clouds. We infer from paleoclimate data that aerosol cooling offset GHG warming for several millennia as civilization developed. A hinge-point in global warming occurred in 1970 as increased GHG warming outpaced aerosol cooling, leading to global warming of 0.18{\deg}C per decade. Aerosol cooling is larger than estimated in the current IPCC report, but it has declined since 2010 because of aerosol reductions in China and shipping. Without unprecedented global actions to reduce GHG growth, 2010 could be another hinge point, with global warming in following decades 50-100% greater than in the prior 40 years. The enormity of consequences of warming in the pipeline demands a new approach addressing legacy and future emissions. The essential requirement to "save" young people and future generations is return to Holocene-level global temperature. Three urgently required actions are: 1) a global increasing price on GHG emissions, 2) purposeful intervention to rapidly phase down present massive geoengineering of Earth's climate, and 3) renewed East-West cooperation in a way that accommodates developing world needs.
Explore the paper tree
Click on the tree nodes to be redirected to a given paper and access their summaries and virtual assistant
Look for similar papers (in beta version)
By clicking on the button above, our algorithm will scan all papers in our database to find the closest based on the contents of the full papers and not just on metadata. Please note that it only works for papers that we have generated summaries for and you can rerun it from time to time to get a more accurate result while our database grows.