State dependence of CO 2 forcing and its implications for climate sensitivity.

Publisher: American Association for the Advancement of Science Country of Publication: United States NLM ID: 0404511 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1095-9203 (Electronic) Linking ISSN: 00368075 NLM ISO Abbreviation: Science Subsets: PubMed not MEDLINE; MEDLINE

Publication: : Washington, DC : American Association for the Advancement of Science
Original Publication: New York, N.Y. : [s.n.] 1880-

When evaluating the effect of carbon dioxide (CO 2 ) changes on Earth's climate, it is widely assumed that instantaneous radiative forcing from a doubling of a given CO 2 concentration (IRF 2×CO2 ) is constant and that variances in climate sensitivity arise from differences in radiative feedbacks or dependence of these feedbacks on the climatological base state. Here, we show that the IRF 2×CO2 is not constant, but rather depends on the climatological base state, increasing by about 25% for every doubling of CO 2 , and has increased by about 10% since the preindustrial era primarily due to the cooling within the upper stratosphere, implying a proportionate increase in climate sensitivity. This base-state dependence also explains about half of the intermodel spread in IRF 2×CO2 , a problem that has persisted among climate models for nearly three decades.

Date Created: 20231130 Latest Revision: 20231130

20231201

10.1126/science.abq6872

38033059