The Sea Level Rise The Sea Level Rise StoryStory

Bruno TremblayBruno Tremblay

McGill UniversityMcGill University

bruno.tremblay@mcgill.ca

Slide from Steven Nerem – University of Colorado

Annual Global Mean Surface Temperatures

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1880 1900 1920 1940 1960 1980 2000

°C

Year [Hansen et al., 2005]

Observed Sea Level Rise

Observed Sea Level RiseLast 20 Kyr BP

Measuring sea level height

Tidal gaugeRadar altimetry

Cause of Sea Level Rise Eustatic:

Water mass added. Steric:

Salinity or temperature change Isostatic:

Change in the level of land (e.g. thermal effect, plate tectonic, compaction effect)

Withdrawal of ground water land subsidence.

Cooling of volcanic island land subsidence.

Short Term Changes in Sea Level

Diurnal-semidiurnal tides Atmospheric pressure – Winds - Evaporation-

precipitations  Water density and currents El Niño/southern oscillation Water mass exchange between Arctic, Atlantic,

Pacific, Indian Oceans River runoff/floods Seiches Tsunamis Abrupt change in land level

Potential Sea Level Rise

Glaciers: 0.5 m Greenland: 6m Antarctica

West: 6m East: 51m

Potential Sea Level Change Contributions

Thermal Expansion: ~1 meter

Mountain Glaciers: 0.5 meters

Greenland Ice Melt: 7 meters

Antarctic Ice Melt: 60 meters

Land Water Storage: < 0.5 meters

Recent contributio

n to observed sea level

rise

Rhone Glacier

1900 2008

Alaska Mass Change from Grace

Ice Sheet Mass Balance

8 mm/yr of precip and calving at equilibrium

Greenland Ice Mass Loss from GRACE

Credit: Roger Braithwaite

362 Gt = 1 mm GMSL

-210 Gt/year = 0.6 mm/year GMSL

Antarctic Ice Mass Flux from InSAR

SLR 0.4 to 0.6 mm/yr

-114 km3/yr

-37±20 km3/yr

+33 km3/yr

-38 km3/yr+48 km3/yr

-2 km3/yr

+5 km3/yr

-22 km3/yr

-3 km3/yr

+5 km3/yr

-2 km3/yr

-56 km3/yr

-2 km3/yr

+21 km3/yr

-4 km3/yr

-33 km3/yr

-4 km3/yr

-49±20 km3/yr

[Rignot, 2005]GRACE

Ice Sheet - Ice Shelf

Wilkins Ice Shelf

Larsen B Ice Shelf

AntarcticaWithout Ice

Recent contributio

n to observed sea level

rise

Sea Level Observations versus Predictions

[Rahmstorf et al., 2007]

Tide Gauge Observations

Satellite Observations

Climate Model Predictions(IPCC 3rd Assessment, 2001)

What to Expect in the Future

The IPCC 4th Assessment: 0.28 - 0.59 m by 2100

Recent study suggests higher rates (0.5 - 1.4 m by 2100).

[Rahmstorf, 2007]

1.4°

5.8°

Greenland Ice Mass Loss Estimates

Luthcke et al. [2006]Krabill et al. [2004]Zwally et al. [2005]Rignot et al. [2006]Velicogna and Wahr [2005]Ramillien et al. [2006]Chen et al. [2006]Velicogna and Wahr [2006]

[Cazenave, 2006]

362 Gt = 1 mm GMSL

Antarctic Ice Mass Loss Estimates

Rignot and Thomas [2002]Zwally et al. [2005]Davis et al. [2005]Velicogna and Wahr [2006]Chen et al. [2006]Ramillien et al. [2006]

[Cazenave, 2006]

362 Gt = 1 mm GMSL

Effects of Sea Level Rise

1 meter 2 meters

4 meters 8 meters GFDL