edu.ucar.opensky::articles:23686 UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact 2025-12-25T15:00:53.225928 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) https://n2t.org/ark:/85065/d7057k67 https://doi.org/10.22033/ESGF/CMIP6.10062 https Related Dataset #1 NCAR CESM2-WACCM model output prepared for CMIP6 AerChemMIP hist-piNTCF https://doi.org/10.7265/N59P2ZTG https Related Dataset #2 NOAA/NSIDC Climate Data Record of Passive Microwave Sea Ice Concentration, Version 3 https://doi.org/10.22033/ESGF/CMIP6.10104 https Related Dataset #3 NCAR CESM2-WACCM model output prepared for CMIP6 AerChemMIP ssp370-lowNTCF Arctic sea ice in two configurations of the CESM2 during the 20th and 21st centuries 2020-09-07T00:00:00Z publication https://n2t.org/ark:/85065/d7057k67 https://doi.org/10.1029/2020JC016133 DeRepentigny, P. author Jahn, A. author Holland, Marika M. author Smith, A. author UCAR/NCAR - Library publisher We provide an assessment of the current and future states of Arctic sea ice simulated by the Community Earth System Model version 2 (CESM2). The CESM2 is the version of the CESM contributed to the sixth phase of the Coupled Model Intercomparison Project (CMIP6). We analyze changes in Arctic sea ice cover in two CESM2 configurations with differing atmospheric components: the CESM2(CAM6) and the CESM2(WACCM6). Over the historical period, the CESM2(CAM6) winter ice thickness distribution is biased thin, which leads to lower summer ice area compared to CESM2(WACCM6) and observations. In both CESM2 configurations, the timing of first ice-free conditions is insensitive to the choice of CMIP6 future emissions scenario. In fact, the probability of an ice-free Arctic summer remains low only if global warming stays below 1.5 degrees C, which none of the CMIP6 scenarios achieve. By the end of the 21st century, the CESM2 simulates less ocean heat loss during the fall months compared to its previous version, delaying sea ice formation and leading to ice-free conditions for up to 8 months under the high emissions scenario. As a result, both CESM2 configurations exhibit an accelerated decline in winter and spring ice area, a behavior that had not been previously seen in CESM simulations. Differences in climate sensitivity and higher levels of atmospheric CO(2)by 2100 in the CMIP6 high emissions scenario compared to its CMIP5 analog could explain why this winter ice loss was not previously simulated by the CESM. UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact PDF Text theme Resource Type 2016-01-01T00:00:00Z publication Copyright author(s). This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License. None eng geoscientificInformation