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Ice Sheet Mass Balance and Sea Level Portland, Oregon, USA 14 July 2012 ISMASSISMASS 20122012 WorkshopWorkshop IceIce SheetSheet MassMass BalanceBalance andand SeaSea LevelLevel Edward Hanna Francisco Navarro Frank Pattyn OrganizersOrganizers andand sponsorssponsors Organizing and sponsoring: Scientific Committee on Antartic Research (SCAR) International Arctic Science Committee (IASC) World Climate Research Programme (WCRP) with organizing support from WCRP/CliC & APECS Sponsoring: International Council of Scientific Unions (ICSU) International Glaciological Society (IGS) Internat. Association of Cryospheric Sciences (IACS) ISMASSISMASS SteeringSteering CommitteeCommittee From SCAR Buenos Aires 2010 Meeting till autumn 2011: Kees van der Veen, University of Kansas. Christina Hulbe, Portland State University. Francisco Navarro, Technical University of Madrid. Under co-sponsorship of SCAR & IASC, from autumn 2011 till present, interim SC: Frank Pattyn, Un. Libre Bruxelles (representing SCAR). Francisco Navarro, TU Madrid (representing IASC). Edward Hanna, Univ. Sheffield (representing WCRP). ISMASSISMASS 20122012 WorkshopWorkshop aimsaims To assess the current knowledge of the contribution of the Antarctic and Greenland Ice Sheets to SLR (focus on quantifying uncertainties and understanding discrepancies). To analyze how model-based predictions of ice-sheet discharge and melting contributions to sea-level changes can be improved (emphasis on identifying shortcomings and suggesting improvements, and on interactions with oceans and atmosphere). To study other contributions to SLR (e.g. thermal expansion of oceans). To analyze the impacts of SLR on coastal areas. To determine how the renewed SCAR-IASC ISMASS group should be organized to effectively meet its objectives. OutlineOutline ofof AgendaAgenda 08:30-10:00 – Invited lectures (mass balance from remote sensing; glacial isostatic adjustment) 10:00-10:30 – Coffee break 10:30-12:30 – Invited lectures (modelling of ice-sheet dynamics; contributions to seal level rise from thermal expansion of the oceans; impacts of SLR) 12:30-13:30 – Buffet lunch 13:30-15:30 – 3 round tables, 40 min. each 15:30-16:00 – Coffee break 16:00-17:30 – ISMASS group organization session 17:30-18:00 – Presentation of conclusions, and closing FirstFirst blockblock ofof invitedinvited lectures:lectures: MBMB fromfrom remoteremote sensing,sensing, andand GIAGIA 08:30-09:00 – Overview of the Ice Mass Balance Inter- comparison Exercise (IMBIE) project findings (Erik Ivins, JPL, Caltech, USA, and Ben Smith, APL, University of Washington, USA) 09:00-09:30 – What is a GIA model, and why do we need it to determine ice-mass balance? (Pippa Whitehouse, Durham University, UK) 09:30-10:00 – Mass Balance of Antarctic Ice Sheet 1992 to 2008 from ERS and ICESat: Gains Exceed Losses (Jay Zwally, NASA Goddard, USA) SecondSecond blockblock ofof invitedinvited lectures:lectures: ISIS modelling,modelling, thermalthermal exp.exp. oceans,oceans, impactsimpacts 10:30-11:00 – Modelling the evolution of Antarctica and Greenland ice sheets: recent improvements and challenges for the future (Catherine Ritz, LGGE, France) 11:00-11:30 – Convergence of models and reality? Bothersome boundary conditions (Slawek Tulaczyk, University of California Santa Cruz, USA) 11:30-12:00 – Ocean thermal expansion and its contribution to sea-level rise over the past 40 years (1960-present) (Catia Domingues, ACE CRC, Australia) 12:00-12:30 – Global impacts of sea-level rise (Robert Nicholls, University of Southampton, UK) RoundRound tablestables 13:30-14:10 – Ice-sheet MB from remote sensing, and GIA Moderator: Edward Hanna At table: Erik Ivins, Ben Smith, Pippa Whitehouse, Jay Zwally 14:10-14:50 – Modelling of ice-sheet dynamics Moderator: Frank Pattyn At table: Catherine Ritz, Slawek Tulaczyk 14:50-15:30 – Thermal exp. of oceans, and impacts of SLR Moderator: Francisco Navarro At table: Catia Domingues, Robert Nicholls RoundRound tabletable 11 -- RemoteRemote sensing:sensing: relatedrelated ISMASSISMASS 20122012 WorkshopWorkshop aimsaims To assess the current knowledge of the contribution of the Antarctic and Greenland Ice Sheets to SLR (focus on quantifying uncertainties and understanding discrepancies). To analyze how model-based predictions of ice-sheet discharge and melting contributions to sea-level changes can be improved (emphasis on identifying shortcomings and suggesting improvements, and on interactions with oceans and atmosphere). To study other contributions to SLR (e.g. thermal expansion of oceans). To analyze the impacts of SLR on coastal areas. To determine how the renewed SCAR-IASC ISMASS group should be organized to effectively meet its objectives. RoundRound tabletable 1:1: RemoteRemote sensingsensing--somesome keykey pointspoints Poor agreement remains between various observation-based mass balance estimation methods: need to reconcile these. Error estimates & uncertainties - re. delta MB. Need to accurately discriminate 1-2% changes in Antarctic (& Greenland) mass balance (SLE)? Required/continuous coverage of satellite MB observations. RoundRound tabletable 1:1: RemoteRemote sensingsensing--somesome keykey pointspoints Acknowledged more important role of postglacial rebound model corrections in mass balance estimates. Need for more GPS measurements in data-poor regions. Integrating different satellite methods. Palaeoglaciological analogues. Firn compaction also important. Antarctic sea-level contribution reduced compared with previous estimates. Required coverage of satellite MB observations. Surface mass balance uncertain & high impact. Need of field data for SMB and dh/dt model validation. RoundRound tabletable 22 -- IceIce--sheetsheet modellingmodelling:: relatedrelated ISMASSISMASS 20122012 WorkshopWorkshop aimsaims To assess the current knowledge of the contribution of the Antarctic and Greenland Ice Sheets to SLR (focus on quantifying uncertainties and understanding discrepancies). To analyze how model-based predictions of ice-sheet discharge and melting contributions to sea-level changes can be improved (emphasis on identifying shortcomings and suggesting improvements, and on interactions with oceans and atmosphere). To study other contributions to SLR (e.g. thermal expansion of oceans). To analyze the impacts of SLR on coastal areas. To determine how the renewed SCAR-IASC ISMASS group should be organized to effectively meet its objectives. RoundRound tabletable 2:2: IceIce--sheetsheet modellingmodelling There has been a major improvement of ice sheet models since AR4: full-Stokes, higher-order, grounding line migration, dynamic evolution, initialization (inversion). AR5 will incorporate a number of process studies, but a certain degree of (cross)scaling will still be necessary. What improvements are needed for AR6? What is needed in terms of targeted observations/datasets for modellers/process understanding? RoundRound tabletable 2:2: Process./Process./observobserv.. needsneeds Assessments between ARs (7 years is a long time)? Demands a lot of energy. ISMASS as an authority to produce these? LGM to present: reconstructions of the past and Melt Water Pulse 1A. Linking GIA models with ice sheet models linked to GL motion/ocean interaction. Thermal and hydrological processes; widening of ice streams and their margins. RoundRound tabletable 2:2: OtherOther remarks/recommend.remarks/recommend. Calving: calving laws - comprehensive observations linking calving to atmosphere/ocean processes. Basal sliding (plastic vs viscous vs nonlinear). Ice-ocean interactions (coupling models at different scales), observations (melting-refreezing under ice shelves), ocean measurements, cavity shapes (data). Lack of velocity data (evolving over time) - is all data out there properly used? Lack of bedrock data (under-resolution) - raw data are often preferred (unstructured grids). RoundRound tabletable 33 -- ThermosteticThermostetic SLRSLR && SLRSLR impactsimpacts relatedrelated ISMASSISMASS 20122012 WorkshopWorkshop aimsaims To assess the current knowledge of the contribution of the Antarctic and Greenland Ice Sheets to SLR (focus on quantifying uncertainties and understanding discrepancies). To analyze how model-based predictions of ice-sheet discharge and melting contributions to sea-level changes can be improved (emphasis on identifying shortcomings and suggesting improvements, and on interactions with oceans and atmosphere). To study other contributions to SLR (e.g. thermal expansion of oceans). To analyze the impacts of SLR on coastal areas. To determine how the renewed SCAR-IASC ISMASS group should be organized to effectively meet its objectives. RoundRound tabletable 3:3: ThermosteticThermostetic SLRSLR Need to reduce uncertainties introduced by instrumental bias corrections and mapping approaches in estimates of the global evolution of thermosteric sea level and its spatio- temporal variability. Need to improve the quality and consistency of the ocean subsurface measurements (temperature, salinity) to meet the more demanding climate-related requirements. Need to expand the current ocean monitoring system to coastal boundaries/marginal seas; below 2000 m; under sea ice coverage/nearby ice sheets (water properties, mixing and circulation changes). RoundRound tabletable 3:3: ImpactsImpacts ofof SLRSLR What are the impacts of different global sea-level rise scenarios? – With socio-economic developments? – With subsidence? – With and without adaptation? – With and without other climate change (storms)? Understanding
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