The response of the Southern Ocean and Antarctic sea ice to
Details of Research
TitleThe response of the Southern Ocean and Antarctic sea ice to freshwater from ice shelves in an earth system modelAbstractThe possibility that recent Antarctic sea ice expansion resulted from an increase in freshwater reaching the Southern Ocean is investigated here. The freshwater flux from ice sheet and ice shelf mass imbalance is largely missing in models that participated in phase 5 of the Coupled Model Intercomparison Project (CMIP5). However, on average, precipitation minus evaporation (P2E) reaching the Southern Ocean has increased inCMIP5 models to a present value that is about 2600 Gt yr-1 greater than preindustrial times and 5-22 times larger than estimates of themass imbalance of Antarctic ice sheets and shelves (119-544Gt yr-1). Two sets of experiments were conducted from 1980 to 2013 in CESM1(CAM5), one of the CMIP5 models, artificially distributing freshwater either at the ocean surface to mimic iceberg melt or at the ice shelf fronts at depth.An anomalous reduction in vertical advection of heat into the surface mixed layer resulted in sea surface cooling at high southern latitudes and an associated increase in sea ice area. Enhancing the freshwater input by an amount within the range of estimates of the Antarctic mass imbalance did not have any significant effect on either sea ice area magnitude or trend. Freshwater enhancement of 2000 Gt yr-1 raised the total sea ice area by 1 — 106km2, yet this and even an enhancement of 3000Gt yr-1 was insufficient to offset the sea ice decline due to anthropogenic forcing for any period of 20 years or longer. Further, the sea ice response was found to be insensitive to the depth of freshwater injection. Copyright 2016 American Meteorological Society.AcknowledgementsWe thank three anonymous reviewers whose detailed and thoughtful comments helped greatly in preparing the manuscript. We thank Dr. Torge Martin for providing the iceberg melt distributions from his earlier study and for helpful discussions. CMB gratefully acknowledges receiving a Fulbright U.S. Senior Scholar award along with the support of Fulbright New Zealand and funding from the National Science Foundation through Grant PLR-1341497. PJL and IJS were supported through University of Otago Research Grant 111030 and two subcontracts to NIWA: one for the Ministry of Business, Innovation, and Employment funded project 'Climatic variability in the Ross Sea region of Antarctica and its potential influences on the marine ecosystem'(CO1X1226), and one from Crown Research Institute core funding. The authors wish to acknowledge the contribution of NeSI high-performance computing facilities to the results of this research. NZÅ› national facilities are provided by the NZ eScience Infrastructure and funded jointly by NeSIÅ› collaborator institutions and through the Ministry of Business, Innovation and EmploymentÅ› Research Infrastructure programme. We thank Peter Maxwell in particular for his assistance in running CESM1(CAM5) on the cluster. We would like to acknowledge high-performance computing support from Yellowstone (ark:/85065/d7wd3xhc) provided by NCARÅ› Computational and Information Systems Laboratory, sponsored by the National Science Foundation. AGPÅ› initial involvement in the project was supported by a University of Otago Summer Scholarship from the Polar Environments Research Theme, and his continued involvement through a Kelly TarltonÅ› Antarctic Scholarship (awarded through the Antarctica New Zealand Postgraduate Research Scholarships Programme). We acknowledge the CESM1(CAM5) Large Ensemble Community Project and the World Climate Research Programme's Working Group on Coupled Modelling, which is responsible for CMIP. We thank the climate modelling groups (shown in Fig. 5 of this paper) for producing and making available their model output. For CMIP, the U.S. Department of EnergyÅ› Program for Climate Model Diagnosis and Intercomparison provides coordinating support and led development of software infrastructure in partnership with the Global Organization for Earth System Science Portals.Funding DetailsPLR-1341497, NSF, National Science Foundation
Details
1st AuthorPauling, A.AuthorPauling, A.Bitz, C.Smith, I.Langhorne, P.Year2016JournalJournal of ClimateVolume29Number5Pages1655-1672DOI10.1175/JCLI-D-15-0501.1URLhttps://www.scopus.com/inward/recor.....d730c3783f32f675b89fcda33KeywordsClimate modelsGlaciersOceanographySea iceSurface watersWater, AntarcticaFreshwaterGeneral circulation modelGeographic locationIce shelvesOceanic mixed layers, Ice, freshwater inputgeneral circulation modelice sheetice shelfmixed layersea ice, AntarcticaSouthern Ocean, rank5Author KeywordsAntarcticaAtm/Ocean Structure/PhenomenaFreshwaterGeneral circulation modelsGeographic location/entityIce shelvesModels and modelingOceanic mixed layerSea ice
Other
TypeArticleCitationPauling, A., Bitz, C., Smith, I. and Langhorne, P. (2016). The response of the Southern Ocean and Antarctic sea ice to freshwater from ice shelves in an earth system model. Journal of Climate, 29(5): 1655-1672 IdentifierPauling2016Relevancerank5
Langhorne, P., The response of the Southern Ocean and Antarctic sea ice to , [Pauling2016]. Antarctica NZ, accessed 17/03/2025, https://adam.antarcticanz.govt.nz/nodes/view/63715, 10.1175/JCLI-D-15-0501.1