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DOI	10.1088/1748-9326/ab63e3
	On the relationship between Atlantic meridional overturning circulation slowdown and global surface warming
	Caesar L.; Rahmstorf S.; Feulner G.
发表日期	2020
ISSN	17489318
卷号	15 期号:2
英文摘要	According to established understanding, deep-water formation in the North Atlantic and Southern Ocean keeps the deep ocean cold, counter-acting the downward mixing of heat from the warmer surface waters in the bulk of the world ocean. Therefore, periods of strong Atlantic meridional overturning circulation (AMOC) are expected to coincide with cooling of the deep ocean and warming of the surface waters. It has recently been proposed that this relation may have reversed due to global warming, and that during the past decades a strong AMOC coincides with warming of the deep ocean and relative cooling of the surface, by transporting increasingly warmer waters downward. Here we present multiple lines of evidence, including a statistical evaluation of the observed global mean temperature, ocean heat content, and different AMOC proxies, that lead to the opposite conclusion: even during the current ongoing global temperature rise a strong AMOC warms the surface. The observed weakening of the AMOC has therefore delayed global surface warming rather than enhancing it. Social Media Abstract: The overturning circulation in the Atlantic Ocean has weakened in response to global warming, as predicted by climate models. Since it plays an important role in transporting heat, nutrients and carbon, a slowdown will affect global climate processes and the global mean temperature. Scientists have questioned whether this slowdown has worked to cool or warm global surface temperatures. This study analyses the overturning strength and global mean temperature evolution of the past decades and shows that a slowdown acts to reduce the global mean temperature. This is because a slower overturning means less water sinks into the deep ocean in the subpolar North Atlantic. As the surface waters are cold there, the sinking normally cools the deep ocean and thereby indirectly warms the surface, thus less sinking implies less surface warming and has a cooling effect. For the foreseeable future, this means that the slowing of the overturning will likely continue to slightly reduce the effect of the general warming due to increasing greenhouse gas concentrations. © 2020 The Author(s). Published by IOP Publishing Ltd.
英文关键词	Atlantic meridional overturning circulation; global surface warming; ocean heat uptake
语种	英语
scopus关键词	Climate models; Global warming; Greenhouse effect; Greenhouse gases; Surface waters; Atlantic meridional overturning circulations; Global surface temperature; Global surface warming; Global-mean temperature; Ocean heat uptake; Overturning circulation; Statistical evaluation; Subpolar North Atlantic; Oceanography; air-sea interaction; cooling; deep water; global climate; global warming; greenhouse gas; heat transfer; meridional circulation; mixing ratio; proxy climate record; surface layer; Atlantic Ocean; Atlantic Ocean (North); Southern Ocean
来源期刊	Environmental Research Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/154121
作者单位	Potsdam Institute for Climate Impact Research (PIK), Member of the Leibniz Association, PO Box 60 12 03, Potsdam, D-14412, Germany; Institute of Physics and Astronomy, University of Potsdam, Potsdam, Germany; Irish Climate Analysis and Research UnitS (ICARUS), Department of Geography, Maynooth University, Maynooth, Ireland
推荐引用方式 GB/T 7714	Caesar L.,Rahmstorf S.,Feulner G.. On the relationship between Atlantic meridional overturning circulation slowdown and global surface warming[J],2020,15(2).
APA	Caesar L.,Rahmstorf S.,&Feulner G..(2020).On the relationship between Atlantic meridional overturning circulation slowdown and global surface warming.Environmental Research Letters,15(2).
MLA	Caesar L.,et al."On the relationship between Atlantic meridional overturning circulation slowdown and global surface warming".Environmental Research Letters 15.2(2020).