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A Community Effort to Inform IPCC-AR5 of Reasonable Ice Sheet Contributions to Sea Level

A Community Effort to Inform IPCC-AR5 of Reasonable Ice Sheet Contributions to Sea Level. Sea -level R esponse to I ce S heet E volution. Origins. Satellite data have captured large and rapid ice-sheet changes Acceleration, thinning, calving, disintegration in multiple locations

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A Community Effort to Inform IPCC-AR5 of Reasonable Ice Sheet Contributions to Sea Level

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  1. A Community Effort to Inform IPCC-AR5 of Reasonable Ice Sheet Contributions to Sea Level Sea-level Response to Ice Sheet Evolution

  2. Origins • Satellite data have captured large and rapid ice-sheet changes • Acceleration, thinning, calving, disintegration in multiple locations • IPCC -AR4 articulated weaknesses in ice sheet models and in understanding of ice dynamic processes • LANL workshop (August 2008; Lipscomb et al. in press) • CCSM is on path to couple advanced-physics ice sheet to NCAR climate model • Not fast enough for IPCC AR5 • “Assessment “ cluster spawned

  3. Goal and Strategy • Goal: provide quantitative estimates of ice sheet contributions to sea level for the 21st century • Inform the IPCC AR5 • Identify upper bound and work toward increasing likelihood • e.g., start with removing all Antarctic ice shelves and activating retreat/thinning of all Greenland outlet glaciers • How bad could it ever possibly get? • complements Ice2Sea

  4. More Strategy • Multiple models • Everyone is more right than any one • Use common “best” data sets • Posted at CISM web site (U/Montana)

  5. Data Sets Available at U/Montana • Present day Antarctica data sets. Right now this consists of: • Mean Annual Surface Temperature • Ice Thickness • Accumulation/Ablation Rate • Ice Surface Elevation • Bed Topography • Basal Heat Flux • Thickness Mask • Surface Velocity • Melt(Ross ice streams) • Surface Balance Velocity • Present day Greenland data sets. Right now this consists of : • Ice Thickness • Bed Topography • Ice Surface Elevation • Precipitation • Basal Heat Flux • Mean Annual Near-surface(2m) Air Temperature

  6. Yet More Strategy • 3 model categories • Whole ice sheet • Ice-stream/ice-shelf • Ice-shelf/ocean

  7. Whole Ice Sheet • Each starts from its own control run • Varying “spin-up” approaches • All use common future climate gleaned from IPCC-AR4 results (thanks to Tom Bracegirdle) • Run for 100, 200 and 500 years • Scenario “experiments” are compared to a model’s own control run • SeaRISE is NOT a model intercomparison project

  8. Participating Whole Ice Sheet Models • CISM/CCSM (built on GLIMMER) • PISM • Penn State U • U Maine • SICOPOLIS • GLAM • ICIES

  9. Regional models • Initialized from control runs of whole ice sheet models • Inform the whole ice sheet models through forcing boundary conditions, e.g., prescribe: • rate of grounding line retreat; • changing ice shelf backpressure; • perimeter thinning • basal lubrication from surface meltwater

  10. Ice-Stream/Ice-Shelf Regional Models • 2D or greater • Hulbe • Goldberg • Bassis (2.25-2.5D; an inverse approach) • Price/Payne (GLAM) • 1D,2D • Dupont • Parizek (no thermodynamics) • Price/Payne (GLAM run as vertical slice in the x,z plane)

  11. Ice-Shelf/Ocean Regional Models • 3D • HYPOP and CISM (Los Alamos National Lab; Ringler/Price/Lipscomb • ROMS (Old Dominion University; Klinck/Dinniman; no dynamical ice yet) • HIM (Ocean) (Geophysical Fluids Dynamics Lab; Little; no dynamical ice yet) • MICOM (Ocean) and CISM (University of Bergen ; Drange) • FESOM (Ocean) (Alfred Wegener Institute; Hellmer; and Hadley Center Ice Sheet) • 2D-Vertical • HYPOP and CISM (Los Alamos National Lab; Ringler/Price/Lipscomb • Stream Function Ocean Flowline Ice (Penn State University; Walker/Dupont; includes an ice stream) • 2D-Horizontal • Plume Ocean, CISM (New York University; Gladish/D.Holland; British Antarctic Survey; P.Holland; and Los Alamos National Lab; Lipscomb)

  12. Timetable • Control runs complete 2Q/2009 • 1st set of experiments complete by 4Q/2009 • Review results and define 2nd set of experiments by 2Q/2010 • Regional models generate prescribed forcing fields • 2nd set of experiments complete by 4Q/2010 • Possible 3rd round of experiments in 2011 • Review results and write papers by 1Q/2012 • Published input must be in press November 2012 • IPCC-AR5 will be finalized in 2014 • Scoping Meeting in July 2009 will set scope and timing

  13. Participants • Robert Bindschadler (NASA GSFC) • Ayako Abe-Ouchi (U. Tokyo) • Andy Aschwanden (ETH) • Richard Alley (Penn State) • Jeremy Bassis (U. Chicago) • Ed Bueler (UAF) • Bea Csatho (U Buffalo) • Mike Dinniman (Old Dominion) • Todd Dupont (UC Irvine) • Jim Fastook (U. Maine) • Carl Gladish (NYU/Courant) • Dan Goldberg (NYU/Courant/GFDL) • Ralf Greve (LTI/Hokaido) • David Holland (NYU/Courant) • Paul Holland (BAS) • Christina Hulbe (Portland State) • Charles Jackson (UTIG) • Jesse Johnson (U. Mont.) • John Klinck (Old Dominion) • Constantine Khroulev (UAF) • Anders Levermann (Potsdam) • Bill Lipscomb (LANL) • Doug MacAyeal (U. Chicago) • Maria Martin (Potsdam) • Byron Parizek (Penn State) • David Pollard (Penn State) • Steve Price (LANL) • Fuyuki Saito (Japan) • Olga Sergienko (Portland State) • Miren Vizcaino Trueba (UC Berkeley) • Slawek Tulaczyk (UC Santa Cruz) • Kees van der Veen (KU/CReSIS) • Ryan Walker (Penn State) • Weili Wang (NASA GSFC) Others are welcome

  14. Interaction • E-mail and Bi-weekly telecoms • 1st meeting at CCSM workshop (Breckenridge, CO) June 18, 2009 • Compare control runs • Specify first set of experiments • Anticipate semi-annual workshops • Documentation:

  15. Interaction • 1st meeting at CCSM workshop (Breckenridge, CO) June 18, 2009 • Compare control runs • Specify first set of experiments Should we meet earlier tomorrow? 8:30am?

  16. http://oceans11.lanl.gov/trac/CISM/wiki/AssessmentGroup http://websrv.cs.umt.edu/isis/index.php/Main_Page

  17. Questions?

  18. IPCC Report Evolution • 1990 – no mention of ice dynamics; time-scale thought too long for focus on 2100 • 1995 – West Antarctic collapse mentioned as high-risk/ low probability event • 2001 – feedback emphasizing importance of ice dynamics all but ignored • 2007 – dramatic ice dynamics clearly identified as a limitation to prediction

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