On the risk of abrupt changes in the North Atlantic subpolar gyre in CMIP6 models

Annals of the New York Academy of Sciences, Journal Year: 2021, Volume and Issue: 1504(1), P. 187 - 201

Published: July 2, 2021

Abstract CMIP5 models have been shown to exhibit rapid cooling events in their projections of the North Atlantic subpolar gyre. Here, we analyze CMIP6 archive, searching for such new generation models. Four out 35 instabilities. The climatic impacts these are large on decadal timescales, with a substantial effect surface temperature over Europe, precipitation pattern tropics—most notably Sahel and Amazon regions—and possible impact mean atmospheric circulation. mechanisms leading related collapse deep convection gyre, modifying profoundly oceanic Analysis stratification gyre as compared observations highlights that biases explain relatively well spread trends: showing smallest recent period also show weakest warming trends. exhibiting abrupt rank among 11 best this indicator, risk encountering an event up 36.4%, slightly lower than 45.5% estimated

Language: Английский

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The Arctic Ocean in CMIP6 Models: Biases and Projected Changes in Temperature and Salinity

Earth s Future, Journal Year: 2022, Volume and Issue: 10(2)

Published: Feb. 1, 2022

Abstract We examine the historical evolution and projected changes in hydrography of deep basin Arctic Ocean 23 climate models participating Coupled Model Intercomparison Project Phase 6 (CMIP6). The comparison between simulations observational climatology shows that simulated Atlantic Water (AW) layer is too thick majority models, including multi‐model mean (MMM). Moreover, halocline fresh MMM. Overall our findings indicate there no obvious improvement representation CMIP6 compared to CMIP5. change projections reveal sub‐Arctic seas are outstanding warming hotspots, causing a strong trend AW layer. MMM temperature increase averaged over upper 700 m at end 21st century about 40% 60% higher than global SSP245 SSP585 scenarios, respectively. Salinity few hundred meters decrease However, spread salinity large tendency toward stronger not by all models. identified biases projection uncertainties call for concerted effort major improvements coupled

Language: Английский

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Freshwater forcing of the Atlantic Meridional Overturning Circulation revisited

Nature Climate Change, Journal Year: 2022, Volume and Issue: 12(5), P. 449 - 454

Published: April 7, 2022

Language: Английский

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Possibility for strong northern hemisphere high-latitude cooling under negative emissions

Nature Communications, Journal Year: 2022, Volume and Issue: 13(1)

Published: March 1, 2022

Abstract It is well established that a collapse or strong reduction of the Atlantic meridional overturning circulation (AMOC) would substantially cool northern high latitudes. Here we show there possibility such cooling could be amplified under deliberate CO 2 removal and result in temporary undershoot targeted temperature level. We find this behaviour Earth system models AMOC decline response to anthropogenic forcing. Idealized simulations with one these indicate timing negative emissions relative recovery key setting strength cooling. pronounced temperature-fluctuations at latitudes found entail considerable consequences for sea-ice permafrost extent as latitude ecosystems.

Language: Английский

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A new view on abrupt climate changes and the bipolar seesaw based on paleotemperatures from Iberian Margin sediments

Proceedings of the National Academy of Sciences, Journal Year: 2023, Volume and Issue: 120(12)

Published: March 13, 2023

The last glacial cycle provides the opportunity to investigate large changes in Atlantic Meridional Overturning Circulation (AMOC) beyond small fluctuations evidenced from direct measurements. Paleotemperature records Greenland and North show an abrupt variability, called Dansgaard-Oeschger (DO) events, which is associated with of AMOC. These DO events also have Southern Hemisphere counterparts via thermal bipolar seesaw, a concept describing meridional heat transport leading asynchronous temperature between both hemispheres. However, more pronounced cooling during massive releases icebergs known as Heinrich (H) contrary ice-core-based Greenland. Here, we present high-resolution Iberian Margin Bipolar Seesaw Index discriminate without H events. We that seesaw model generates synthetic best resemble Antarctic when using inputs. Our data-model comparison emphasizes role variability hemispheres clear enhancement implying relationship complex than simple flip-flop two climate states linked tipping point threshold.

Language: Английский

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