{"title":"Northern Hemisphere ice sheets and ocean interactions during the last glacial period in a coupled ice sheet-climate model","authors":"Louise Abot, Aurélien Quiquet, Claire Waelbroeck","doi":"10.5194/cp-2024-51","DOIUrl":null,"url":null,"abstract":"<strong>Abstract.</strong> This study examines the interactions between the Northern Hemisphere ice sheets and the ocean during the last glacial period. We explore the consequences of an ocean subsurface warming on ice sheet dynamics and the associated feedbacks, using the climate model of intermediate complexity iLOVECLIM coupled with the ice sheet model GRISLI. Our study shows that amplified oceanic basal melt rates lead to significant freshwater release from both increased calving and basal melt fluxes. Inland, dynamic thinning occurs over the Eurasian and Iceland ice sheets, leading to destabilization, while the coasts of Greenland and the eastern part of the Laurentide ice sheet are thickening. There, the increased oceanic basal melt rates lead to a reduction in the thickness of the ice shelves and the ice flow at the grounding line, resulting in upstream accumulation. Nevertheless, the influx of fresh water temporarily increases sea-ice extent, reduces convection in the Labrador Sea, weakens the Atlantic meridional overturning circulation, lowers surface temperatures in the Northern Hemisphere and increases the subsurface temperatures in the Nordic Seas. The release of cold and fresh water leads to a decrease in ice sheet discharge (negative feedback) for the Greenland and Eurasian ice sheets. The Laurentide ice sheet is rather stable due to low background temperatures and salinity at shelf drafts in the Baffin Bay and Labrador Sea in the model. Still, we show that we are able to trigger a grounding line retreat by imposing ad-hoc oceanic melt rates (10 m/yr). However, continental ice loss stops as soon as we halt the perturbation. This study emphasizes the complex feedback mechanisms at the ocean-ice sheet interface, stressing the necessity for more accurately constrained model results to enhance our understanding of past changes and the predictions of future ice sheet behaviour and sea level rise.","PeriodicalId":10332,"journal":{"name":"Climate of The Past","volume":"31 1","pages":""},"PeriodicalIF":3.8000,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Climate of The Past","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.5194/cp-2024-51","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Abstract. This study examines the interactions between the Northern Hemisphere ice sheets and the ocean during the last glacial period. We explore the consequences of an ocean subsurface warming on ice sheet dynamics and the associated feedbacks, using the climate model of intermediate complexity iLOVECLIM coupled with the ice sheet model GRISLI. Our study shows that amplified oceanic basal melt rates lead to significant freshwater release from both increased calving and basal melt fluxes. Inland, dynamic thinning occurs over the Eurasian and Iceland ice sheets, leading to destabilization, while the coasts of Greenland and the eastern part of the Laurentide ice sheet are thickening. There, the increased oceanic basal melt rates lead to a reduction in the thickness of the ice shelves and the ice flow at the grounding line, resulting in upstream accumulation. Nevertheless, the influx of fresh water temporarily increases sea-ice extent, reduces convection in the Labrador Sea, weakens the Atlantic meridional overturning circulation, lowers surface temperatures in the Northern Hemisphere and increases the subsurface temperatures in the Nordic Seas. The release of cold and fresh water leads to a decrease in ice sheet discharge (negative feedback) for the Greenland and Eurasian ice sheets. The Laurentide ice sheet is rather stable due to low background temperatures and salinity at shelf drafts in the Baffin Bay and Labrador Sea in the model. Still, we show that we are able to trigger a grounding line retreat by imposing ad-hoc oceanic melt rates (10 m/yr). However, continental ice loss stops as soon as we halt the perturbation. This study emphasizes the complex feedback mechanisms at the ocean-ice sheet interface, stressing the necessity for more accurately constrained model results to enhance our understanding of past changes and the predictions of future ice sheet behaviour and sea level rise.
期刊介绍:
Climate of the Past (CP) is a not-for-profit international scientific journal dedicated to the publication and discussion of research articles, short communications, and review papers on the climate history of the Earth. CP covers all temporal scales of climate change and variability, from geological time through to multidecadal studies of the last century. Studies focusing mainly on present and future climate are not within scope.
The main subject areas are the following:
reconstructions of past climate based on instrumental and historical data as well as proxy data from marine and terrestrial (including ice) archives;
development and validation of new proxies, improvements of the precision and accuracy of proxy data;
theoretical and empirical studies of processes in and feedback mechanisms between all climate system components in relation to past climate change on all space scales and timescales;
simulation of past climate and model-based interpretation of palaeoclimate data for a better understanding of present and future climate variability and climate change.