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Mass and Volume Contribution to Twentieth-century Global Sea Level Rise. L. Miller & B. C. Douglas. Nature vol. 428, 2004. Could water world really happen?. Interaction of temperature change with environmental system. Greenland Ice Sheet 7m GSLR. Antarctic+ GLIS 80m GSLR. - PowerPoint PPT Presentation
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Mass and Volume Contribution to Twentieth-century Global
Sea Level Rise
L. Miller & B. C. Douglas
Nature vol. 428, 2004
Could water world really happen?
Interaction of temperature change with environmental system
Water held in glaciers and small ice caps!!
Greenland Ice Sheet7m GSLR
Antarctic+ GLIS80m GSLR
But by how much ?
1. Volume Change (Total Steric Sea Level, TSSL)
2. Mass Change (Eustatic change)
Exchange of water with atmosphere and continents
Temperature and salinity variations
Gauge Data
Total Steric Changes +Eustatic Changes
Isostatic Changes
Dynamic Height
Depth difference between two surfaces of constant pressure and gravity.
It is derived from hydrographic data (T, S, P)Ocean General Circulation Models (OGCM)
Different Approaches
Yearly average trend 1993-98 (3.2 + 0.2 mm/yr)TSC (temperature) (0-500m) 1993-98 (3.1 + 0.4mm/yr)Residual sea level (0.2 + 0.2 mm/yr)
5 year data trend
Topex/ Poseidon data from 1993-2001 (Cabanes et al., 2001)
*Global mean TSC (0-3000m) (0.5 + 0.05 mm/yr)*Pseudo global mean TSC using data of 25 gauge sites (1.4 + 0.2 mm/yr)*PSMSL record at 25 tide gauge sites (1.6+0.15 mm/yr)
*TSSL= 0.55 + 0.07 mm/yr*HSC 0.05 + 0.02 mm/yr
*470 + 170 km3/yr fresh water*Mass increase 1.35+0.5 mm/yr
(Antonov et al., 2002)
3rd IPCC report (2001)
IPCC adopted best estimates = 1.5 + 0.5 mm/yr
TSC = 0.7 mm/yr
CG = 0.2-0.4 mm/yr
MC = -0.2-0.6 mm/yr
TWS = -1.1- 0.4 mm/yr Sum = -0.8 –2.2 mm/yrAvg = 0.7 mm/yr
0
-
+
Comparison of hydrographic and tide gauge measured sea level change in the
Eastern Pacific
TSSL = 0.5 mm/yrGauge data = 2 mm/yr
Local comparison
a. 0.5 mm/yr
c. 0.9 mm/yrGauge data = 1.7 mm/yr
b. 0.3 mm/yr
Regional comparison in the Eastern N. Atlantic
TSSL = 0.2 mm/yr
Gauge data = 2.1 &
1.9 mm/yr
Regional comparison in the Western N. Atlantic
Gauge data =1.9 mm/yr
Cabanes etal., 20018 sites = 0.5 mm/yr1 site = 6.7 mm/yr (NA)Avg = 1.2 mm/yr
Conclusions
*Overall gauge data = 1.5- 2.0 mm/yr GSLR for 20th century
Hydrographic data = 0.5 mm/yr
Mass Increase due to freshening = 1.4 mm/yr
* Satellite data = 2.5 mm/yr (1993-2003) Decadal data !!
Ocean freshening, sea level rising, sea ice meltingP. Wadhams, W. Munk(GRL., Vol. 31, 2004)
Arctic Sea Ice melting = (625 + 125) Km3/yr
Antarctic Ice thickening = (90 + 3) Km3/yr
Volume of fresh water = (325 + 105) Km3/yr
GSLR = mass + volume 0.6 + 0.5 = 1.1 mm/yr
Thanks
Total steric sea level change
1.Thermosteric change (TC)
2. Halosteric change (SC)
Mass and Volume
L. Miller & B. C. Douglas
Nature vol. 428 2004