Transcript Document

Cryospheric and Hydrologic Contributions
to Global Sea Level Change
M. Tamisiea
Proudman Oceanographic Laboratory
R. Steven Nerem
University of Colorado
AGU Meeting of the Americas, August 8-11, 2010
Measurements of Sea Level Change
GRAVITY
Global Mean Sea Level
60
Jason-1 & 2
TOPEX/Poseidon
50
Trend = 3.3 mm/year
40
30
20
10
0
1994
1996
1998
2000
2002
2004
2006
2008
2010
Mean Sea Level
30
20
Global (3.3 mm/yr)
Tropics (3.3 mm/yr)
Northern (2.5 mm/yr)
Southern (3.5 mm/yr)
MSL (mm)
10
0
-10
-20
-30
-40
1996
2000
2004
Year
2008
Area-Weighted Contribution to GMSL
30
Global (3.3 mm/yr)
20
Tropics (1.6 mm/yr)
Northern (0.5 mm/yr)
Southern (1.2 mm/yr)
MSL (mm)
10
0
-10
-20
-30
-40
1996
2000
Year
2004
2008
MSL Rates in 10° Latitude Bands
5
MSL (mm)
4
3
2
1
0
-60
-50
-40
-30
-20
-10
0
10
Latitude
20
30
40
50
60
Spatial Variations in Sea Level Rise 1993-2010
Detrended GMSL and MEI
8
3
Detrended GMSL
MEI
6
2
4
1
0
0
MEI
MSL (mm)
2
-2
-1
-4
-2
-6
-8
-3
1996
2000
2004
Year
2008
Hydrology Model vs GRACE
[Llovel et al., 2010]
Hydrology Model vs Altimeter GMSL
[Llovel et al., 2010]
Hydrology Model vs Tide Gauge GMSL
[Llovel et al., 2010]
GRACE Secular Trends (2002-2009)
GIA Model
Removed
[Wahr, 2009]
Greenland Ice Mass Changes from GRACE
April, 2002 – June, 2010
Rate of Ice mass change:
All Greenland:
Total Greenland ice volume
-239 Gton/yr
South Greenland: -162 Gton/yr
North Greenland: -77 Gton/yr
(1 Gton = 1 km3 of water)
-239 Gton/yr = 0.66 mm/yr sea level rise
[Wahr, 2010]
Antarctica Ice Mass Variations from GRACE
Total Antarctic ice mass
(noisy because of atmospheric pressure errors)
April, 2002 – June, 2010
Rate of ice mass change:
All Antarctica:
-143 Gton/yr
West Antarctica: -155 Gton/yr
East Antarctica:
+15 Gton/yr
Uncertainty of GIA correction:
All Antarctica:
± 80 Gton/yr
West Antarctica: ± 20 Gton/yr
East Antarctica:
Gton/yr
± 55
-143 Gton/yr = 0.40 mm/yr sea level rise
[Wahr, 2010]
Alaskan Glaciers from GRACE
Rate of mass change between April, 2002 and May, 2010
.
Rate of mass change: -55 Gton/yr = 0.15 mm/yr sea level rise
[Wahr, 2010]
Summary of GRACE Ice GMSL
Contributions
GRACE provides mass loss estimates for entire ice sheets.
Between April 2002 and May/June 2010:
Greenland lost ice at a rate of 239 Gton/yr.
Antarctica lost ice at a rate of 143 Gton/yr.
Alaskan glaciers lost ice at a rate of 55 Gton/yr.
Total: 437 Gt/yr, equivalent to 1.2 mm/yr sea level rise.
Global Ocean Mass from GRACE
20
CSR04
15
GFZ04
MSL (mm)
10
5
0
-5
-10
-15
2002
2004
2006
Year
2008
2010
Global Ocean Mass from GRACE
8
CSR04 (1.0 mm/year)
6
GFZ04 (1.4 mm/year)
4
MSL (mm)
2
0
-2
-4
-6
-8
2002
2004
2006
Year
2008
2010
GIA Correction to GRACE Ocean Mass Rate
Current Sea Level Budget
Thermal Expansion: ~ 1.1 mm/year
+
Mountain Glaciers: ~ 1.2 mm/year
+
Greenland Ice Melt: ~ 0.6 mm/year
+
Antarctic Ice Melt: ~ 0.4 mm/year
Land Water Storage: ?
=
Total: ~ 3.3 mm/year