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Mass and Volume Contribution to Twentieth-century Global Sea Level Rise L. Miller & B. C. Douglas Nature vol. 428, 2004.

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Presentation on theme: "Mass and Volume Contribution to Twentieth-century Global Sea Level Rise L. Miller & B. C. Douglas Nature vol. 428, 2004."— Presentation transcript:

1 Mass and Volume Contribution to Twentieth-century Global Sea Level Rise L. Miller & B. C. Douglas Nature vol. 428, 2004

2 Could water world really happen? Interaction of temperature change with environmental system Water held in glaciers and small ice caps!! Greenland Ice Sheet 7m GSLR Antarctic+ GLIS 80m GSLR

3 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

4 Gauge Data Total Steric Changes + Eustatic Changes Isostatic Changes

5 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)

6 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)

7 *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 km 3 /yr fresh water *Mass increase 1.35+0.5 mm/yr (Antonov et al., 2002)

8 3 rd 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/yr Avg = 0.7 mm/yr 0 - +

9 Comparison of hydrographic and tide gauge measured sea level change in the Eastern Pacific TSSL = 0.5 mm/yr Gauge data = 2 mm/yr

10 Local comparison a. 0.5 mm/yr c.0.9 mm/yr Gauge data = 1.7 mm/yr b. 0.3 mm/yr

11 Regional comparison in the Eastern N. Atlantic TSSL = 0.2 mm/yr Gauge data = 2.1 & 1.9 mm/yr

12 Regional comparison in the Western N. Atlantic Gauge data =1.9 mm/yr Cabanes etal., 2001 8 sites = 0.5 mm/yr 1 site = 6.7 mm/yr (NA) Avg = 1.2 mm/yr

13 Conclusions *Overall gauge data = 1.5- 2.0 mm/yr GSLR for 20 th 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 !!

14 Ocean freshening, sea level rising, sea ice melting P. Wadhams, W. Munk (GRL., Vol. 31, 2004) Arctic Sea Ice melting = (625 + 125) Km 3 /yr Antarctic Ice thickening = (90 + 3) Km 3 /yr Volume of fresh water = (325 + 105) Km 3 /yr GSLR = mass + volume 0.6 + 0.5 = 1.1 mm/yr

15 Thanks

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17 Total steric sea level change 1.Thermosteric change (TC) 2. Halosteric change (SC)

18 Mass and Volume L. Miller & B. C. Douglas Nature vol. 428 2004


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