Last Glacial Maximum pattern effects reduce climate sensitivity estimates

Vincent T. Cooper, Kyle C. Armour, Gregory J. Hakim, Jessica E. Tierney, Matthew B. Osman, Cristian Proistosescu, Yue Dong, Natalie J. Burls, Timothy Andrews, Daniel E. Amrhein, Jiang Zhu, Wenhao Dong, Yi Ming, Philip Chmielowiec

Research output: Contribution to journalArticlepeer-review

Abstract

Here, we show that the Last Glacial Maximum (LGM) provides a stronger constraint on equilibrium climate sensitivity (ECS), the global warming from increasing greenhouse gases, after accounting for temperature patterns. Feedbacks governing ECS depend on spatial patterns of surface temperature (“pattern effects”); hence, using the LGM to constrain future warming requires quantifying how temperature patterns produce different feedbacks during LGM cooling versus modern-day warming. Combining data assimilation reconstructions with atmospheric models, we show that the climate is more sensitive to LGM forcing because ice sheets amplify extratropical cooling where feedbacks are destabilizing. Accounting for LGM pattern effects yields a median modern-day ECS of 2.4°C, 66% range 1.7° to 3.5°C (1.4° to 5.0°C, 5 to 95%), from LGM evidence alone. Combining the LGM with other lines of evidence, the best estimate becomes 2.9°C, 66% range 2.4° to 3.5°C (2.1° to 4.1°C, 5 to 95%), substantially narrowing uncertainty compared to recent assessments.

Original languageEnglish (US)
Article numbereadk9461
JournalScience Advances
Volume10
Issue number16
DOIs
StatePublished - 2024

ASJC Scopus subject areas

  • General

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