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 Sheet 7m GSLR Antarctic+ GLIS 80m 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 ( mm/yr) TSC (temperature) (0-500m) ( mm/yr) Residual sea level ( mm/yr) 5 year data trend Topex/ Poseidon data from (Cabanes et al., 2001)

*Global mean TSC (0-3000m) ( mm/yr) *Pseudo global mean TSC using data of 25 gauge sites ( mm/yr) *PSMSL record at 25 tide gauge sites ( mm/yr) *TSSL= mm/yr *HSC mm/yr * km 3 /yr fresh water *Mass increase mm/yr (Antonov et al., 2002)

3 rd IPCC report (2001) IPCC adopted best estimates = mm/yr TSC = 0.7 mm/yr CG = mm/yr MC = mm/yr TWS = mm/yr Sum = -0.8 –2.2 mm/yr Avg = 0.7 mm/yr 0 - +

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

Local comparison a. 0.5 mm/yr c.0.9 mm/yr Gauge 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., sites = 0.5 mm/yr 1 site = 6.7 mm/yr (NA) Avg = 1.2 mm/yr

Conclusions *Overall gauge data = 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 ( ) Decadal data !!

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