Constraining CMIP6 estimates of Arctic Ocean temperature and salinity in 2025-2055

Global climate models (CMIP6 models) are the basis for future predictions and projections, but these models typically have large biases in their mean state of the Arctic Ocean. Considering a transect across the Arctic Ocean, with a focus on the depths between 100-700m, we show that the model spread...

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Main Authors: Helene Reinertsen Langehaug, Hanne Sagen, A. Stallemo, Petteri Uotila, L. Rautiainen, Steffen Malskær Olsen, Marion Devilliers, Shuting Yang, E. Storheim
Format: Article
Language:English
Published: Frontiers Media S.A. 2023-10-01
Series:Frontiers in Marine Science
Subjects:
Online Access:https://www.frontiersin.org/articles/10.3389/fmars.2023.1211562/full
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author Helene Reinertsen Langehaug
Hanne Sagen
A. Stallemo
Petteri Uotila
L. Rautiainen
Steffen Malskær Olsen
Marion Devilliers
Shuting Yang
E. Storheim
author_facet Helene Reinertsen Langehaug
Hanne Sagen
A. Stallemo
Petteri Uotila
L. Rautiainen
Steffen Malskær Olsen
Marion Devilliers
Shuting Yang
E. Storheim
author_sort Helene Reinertsen Langehaug
collection DOAJ
description Global climate models (CMIP6 models) are the basis for future predictions and projections, but these models typically have large biases in their mean state of the Arctic Ocean. Considering a transect across the Arctic Ocean, with a focus on the depths between 100-700m, we show that the model spread for temperature and salinity anomalies increases significantly during the period 2025-2045. The maximum model spread is reached in the period 2045-2055 with a standard deviation 10 times higher than in 1993-2010. The CMIP6 models agree that there will be warming, but do not agree on the degree of warming. This aspect is important for long-term management of societal and ecological perspectives in the Arctic region. We therefore test a new approach to find models with good performance. We assess how CMIP6 models represent the horizontal patterns of temperature and salinity in the period 1993-2010. Based on this, we find four models with relatively good performance (MPI-ESM1-2-HR, IPSL-CM6A-LR, CESM2-WACCM, MRI-ESM2-0). For a more robust model evaluation, we consider additional metrics (e.g., climate sensitivity, ocean heat transport) and also compare our results with other recent CMIP6 studies in the Arctic Ocean. Based on this, we find that two of the models have an overall better performance (MPI-ESM1-2-HR, IPSL-CM6A-LR). Considering projected changes for temperature for the period 2045-2055 in the high end ssp585 scenario, these two models show a similar warming in the Mid Layer (300-700m; 1.1-1.5°C). However, in the low end ssp126 scenario, IPSL-CM6A-LR shows a considerably higher warming than MPI-ESM1-2-HR. In contrast to the projected warming by both models, the projected salinity changes for the period 2045-2055 are very different; MPI-ESM1-2-HR shows a freshening in the Upper Layer (100-300m), whereas IPSL-CM6A-LR shows a salinification in this layer. This is the case for both scenarios. The source of the model spread appears to be in the Eurasian Basin, where warm waters enter the Arctic. Finally, we recommend being cautious when using the CMIP6 ensemble to assess the future Arctic Ocean, because of the large spread both in performance and the extent of future changes.
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spelling doaj.art-8b0123707dbf4b35a240859672450fa82023-10-25T06:05:12ZengFrontiers Media S.A.Frontiers in Marine Science2296-77452023-10-011010.3389/fmars.2023.12115621211562Constraining CMIP6 estimates of Arctic Ocean temperature and salinity in 2025-2055Helene Reinertsen Langehaug0Hanne Sagen1A. Stallemo2Petteri Uotila3L. Rautiainen4Steffen Malskær Olsen5Marion Devilliers6Shuting Yang7E. Storheim8Nansen Environmental and Remote Sensing Center and Bjerknes Centre for Climate Research, Bergen, NorwayNansen Environmental and Remote Sensing Center, Bergen, NorwayNansen Environmental and Remote Sensing Center, Bergen, NorwayInstitute for Atmospheric and Earth System Research (INAR)/Physics, University of Helsinki, Helsinki, FinlandFinnish Meteorological Institute, Helsinki, FinlandDanish Meteorological Institute, Copenhagen, DenmarkDanish Meteorological Institute, Copenhagen, DenmarkDanish Meteorological Institute, Copenhagen, DenmarkNansen Environmental and Remote Sensing Center, Bergen, NorwayGlobal climate models (CMIP6 models) are the basis for future predictions and projections, but these models typically have large biases in their mean state of the Arctic Ocean. Considering a transect across the Arctic Ocean, with a focus on the depths between 100-700m, we show that the model spread for temperature and salinity anomalies increases significantly during the period 2025-2045. The maximum model spread is reached in the period 2045-2055 with a standard deviation 10 times higher than in 1993-2010. The CMIP6 models agree that there will be warming, but do not agree on the degree of warming. This aspect is important for long-term management of societal and ecological perspectives in the Arctic region. We therefore test a new approach to find models with good performance. We assess how CMIP6 models represent the horizontal patterns of temperature and salinity in the period 1993-2010. Based on this, we find four models with relatively good performance (MPI-ESM1-2-HR, IPSL-CM6A-LR, CESM2-WACCM, MRI-ESM2-0). For a more robust model evaluation, we consider additional metrics (e.g., climate sensitivity, ocean heat transport) and also compare our results with other recent CMIP6 studies in the Arctic Ocean. Based on this, we find that two of the models have an overall better performance (MPI-ESM1-2-HR, IPSL-CM6A-LR). Considering projected changes for temperature for the period 2045-2055 in the high end ssp585 scenario, these two models show a similar warming in the Mid Layer (300-700m; 1.1-1.5°C). However, in the low end ssp126 scenario, IPSL-CM6A-LR shows a considerably higher warming than MPI-ESM1-2-HR. In contrast to the projected warming by both models, the projected salinity changes for the period 2045-2055 are very different; MPI-ESM1-2-HR shows a freshening in the Upper Layer (100-300m), whereas IPSL-CM6A-LR shows a salinification in this layer. This is the case for both scenarios. The source of the model spread appears to be in the Eurasian Basin, where warm waters enter the Arctic. Finally, we recommend being cautious when using the CMIP6 ensemble to assess the future Arctic Ocean, because of the large spread both in performance and the extent of future changes.https://www.frontiersin.org/articles/10.3389/fmars.2023.1211562/fullCentral Arctic Oceanclimate modelstemperaturesalinityfuture scenarios frontiers
spellingShingle Helene Reinertsen Langehaug
Hanne Sagen
A. Stallemo
Petteri Uotila
L. Rautiainen
Steffen Malskær Olsen
Marion Devilliers
Shuting Yang
E. Storheim
Constraining CMIP6 estimates of Arctic Ocean temperature and salinity in 2025-2055
Frontiers in Marine Science
Central Arctic Ocean
climate models
temperature
salinity
future scenarios frontiers
title Constraining CMIP6 estimates of Arctic Ocean temperature and salinity in 2025-2055
title_full Constraining CMIP6 estimates of Arctic Ocean temperature and salinity in 2025-2055
title_fullStr Constraining CMIP6 estimates of Arctic Ocean temperature and salinity in 2025-2055
title_full_unstemmed Constraining CMIP6 estimates of Arctic Ocean temperature and salinity in 2025-2055
title_short Constraining CMIP6 estimates of Arctic Ocean temperature and salinity in 2025-2055
title_sort constraining cmip6 estimates of arctic ocean temperature and salinity in 2025 2055
topic Central Arctic Ocean
climate models
temperature
salinity
future scenarios frontiers
url https://www.frontiersin.org/articles/10.3389/fmars.2023.1211562/full
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