Unit Affiliation: Ocean and Climate Physics, Lamont-Doherty Earth Observatory (LDEO)
The purpose of this project is to illustrate the fate of Arctic sea ice over the next decades. Part A of the project looks at results from an ensemble of global climate model projections. The objective of Part A is to explore the various pathways of future ice loss as simulated by different climate models driven by two radiative forcing scenarios. The impact of climate change on Arctic conditions is diagnosed through sea ice concentration, sea ice thickness and snow depth over ice. Part B completes the picture by running a high-resolution (18km) regional ocean and ice model, providing finer spatial details of ice conditions projected by the GFDL Climate Model version 3 under the business-as-usual RCP8.5 forcing scenario.
OUTCOMES: This work has analyzed an ensemble of CMIP5 participating GCMs to document projected Arctic sea ice retreat. Climatological averages of sea ice concentration, thickness and snow depth were computed for the historical period and two future scenarios going from 2006 to 2100. Ice free days gradients were computed in each case to display the patterns of sea ice retreat. An additional analysis focused on ice concentrations according to its thickness was performed with CCSM4 projections to study the fate of multi-year ice. In the second part of this work, the MITgcm was used to simulate sea ice conditions in the Arctic from 1992 to 2080. The coupled ocean and ice model was driven by atmospheric forcing from JRA-25 reanalyses from 1992 to 2006 and with a climate projection from GFDL-CM3 from 2006 to 2080. Results agree well with sea ice extent and volume observations over the historical period. Sea ice projections indicate a complete disapearance of September sea ice around 2050. Additional runs will be performed to investigate the effect of lateral boundary conditions and bias corrections on the results.