McCarthy, Gerard and Caesar, Levke (2023) Can we trust projections of AMOC weakening based on climate models that cannot reproduce the past? Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 381 (2262). ISSN 1471-2962

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Abstract

The Atlantic Meridional Overturning Circulation (AMOC), a crucial element of the Earth's climate system, is projected to weaken over the course of the twenty-first century which could have far reaching consequences for the occurrence of extreme weather events, regional sea level rise, monsoon regions and the marine ecosystem. The latest IPCC report puts the likelihood of such a weakening as ‘very likely’. As our confidence in future climate projections depends largely on the ability to model the past climate, we take an in-depth look at the difference in the twentieth century evolution of the AMOC based on observational data (including direct observations and various proxy data) and model data from climate model ensembles. We show that both the magnitude of the trend in the AMOC over different time periods and often even the sign of the trend differs between observations and climate model ensemble mean, with the magnitude of the trend difference becoming even greater when looking at the CMIP6 ensemble compared to CMIP5. We discuss possible reasons for this observation-model discrepancy and question what it means to have higher confidence in future projections than historical reproductions. This article is part of a discussion meeting issue 'Atlantic overturning: new observations and challenges'.

Item Type:	Article
Keywords:	Atlantic meridional overturning circulation; climate models; observational reconstructions;
Academic Unit:	Faculty of Social Sciences > Research Institutes > Irish Climate Analysis and Research Units, ICARUS Faculty of Social Sciences > Geography
Item ID:	17729
Identification Number:	https://doi.org/10.1098/rsta.2022.0193
Depositing User:	Vidatum Academic
Date Deposited:	24 Oct 2023 14:19
Journal or Publication Title:	Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
Publisher:	The Royal Society
Refereed:	Yes
URI:	Publisher
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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