# Presentation: 185682

## Reaching for the Grail: Predicting Sea Level Contributions from Dynamic Ice Sheets for 2100 before 2100

## 1990: How will the potentially unstable West Antarctic ice sheet affect future sea level?
1999: How will the unstable West Antarctic ice sheet affect future sea level?
2009:

- 1999: How will the unstable West Antarctic ice sheet affect future sea level?
- 2009:

## IPCC Report Evolution

- 1990 – no mention of ice dynamics; time-scale thought too long for focus on 2100

## 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

## 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

## 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

## “...but..flow rates could increase or decrease in the future.” 

**“...****but..flow rates could increase or decrease in the future.” **
**“****Larger values cannot be excluded...”**
**“...****understanding of these effects is too limited to assess their likelihood or provide a best estimate or an upper bound for sea level rise.”**

## 2008 LANL Workshop “Assessment Cluster” 

- Richard Alley
- Jeremy Bassis
- Ed Bueler
- Robert Bindschadler
- Mike Dinniman
- Todd Dupont
- Jim Fastook
- Carl Gladish
- Dan Goldberg
- David Holland
- Paul Holland
- Christina Hulbe
- Charles Jackson

- Jesse Johnson
- John Klinck
- Bill Lipscomb
- Doug MacAyeal
- Byron Parizek
- David Pollard
- Steve Price
- Christian Schoof
- Olga Sergienko
- Miren Vizcaino Trueba
- Slawek Tulaczyk
- Kees van der Veen
- Ryan Walker

- Participation is not closed

## Goals

- Provide quantitative estimates and uncertainties of land-ice contributions to sea level in time for next IPCC
- Inform land ice model in CCSM

## Approach

- Define extreme scenarios
- Run multiple models
- Compare ensemble results
- Refine scenarios based on results from other domains

## Domains

- Whole ice sheet
- Ice-stream/ice-shelf
- Ice-shelf/ocean

## Whole Ice Sheet 

- Richard Alley
- Jeremy Bassis
- Ed Bueler (PISM)
- Robert Bindschadler
- Mike Dinniman
- Todd Dupont
- Jim Fastook
- Carl Gladish
- Dan Goldberg
- David Holland
- Paul Holland
- Christina Hulbe (CCSM)
- Charles Jackson

- Jesse Johnson (CCSM)
- John Klinck
- Bill Lipscomb (CCSM)
- Doug MacAyeal
- Byron Parizek (2D only)
- David Pollard
- Steve Price (GLIMER)
- Christian Schoof
- Olga Sergienko (SYCOPOLIS)?
- Miren Vizcaino Trueba
- Slawek Tulaczyk
- Kees van der Veen
- Ryan Walker

## Ice-Stream/Ice-Shelf

- Richard Alley
- Jeremy Bassis (inverse approach)
- Ed Bueler
- Robert Bindschadler
- Mike Dinniman
- Todd Dupont
- Jim Fastook
- Carl Gladish
- Dan Goldberg
- David Holland
- Paul Holland
- Christina Hulbe
- Charles Jackson

- Jesse Johnson
- John Klinck
- Bill Lipscomb
- Doug MacAyeal
- Byron Parizek
- David Pollard
- Steve Price
- Christian Schoof
- Olga Sergienko
- Miren Vizcaino Trueba
- Slawek Tulaczyk
- Kees van der Veen
- Ryan Walker

## Ice-Shelf/Ocean 

- Richard Alley
- Jeremy Bassis
- Ed Bueler
- Robert Bindschadler
- Mike Dinniman (ROMS)
- Todd Dupont
- Jim Fastook
- Carl Gladish
- Dan Goldberg
- David Holland
- Paul Holland
- Christina Hulbe
- Charles Jackson

- Jesse Johnson
- John Klinck (ROMS)
- Bill Lipscomb
- Doug MacAyeal
- Byron Parizek
- David Pollard
- Steve Price
- Christian Schoof
- Olga Sergienko
- Miren Vizcaino Trueba
- Slawek Tulaczyk
- Kees van der Veen
- Ryan Walker
- Chris Little (?)

## Preliminary Scenarios (whole ice sheet domain)

- Greenland
- Surface melt (via IPCC) directly into ocean
- Surface melt lubricates whole bed and stays
- Spatially variable basal lubrication
- Remove all ice below equilibrium line
- Antarctica
- Remove all ice shelves
- Drain all subglacial lakes and lubricate bed
- Remove West Antarctica

## Timetable

- Mid- December 2008
- White papers defining scenarios for each domain
- ??
- Distribute input and forcing fields
- Rely on “data sets cluster”
- ??
- Compare results
- Draw conclusions
- More runs?
- Mid-2010
- Write papers for publication by 2011 to satisfy IPCC-5 deadline