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Global Sea Level Rise Laury Miller NOAA Lab for Satellite Altimetry.

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Presentation on theme: "Global Sea Level Rise Laury Miller NOAA Lab for Satellite Altimetry."— Presentation transcript:

1 Global Sea Level Rise Laury Miller NOAA Lab for Satellite Altimetry

2 Why Measure Sea Level Rise? Inundation Will Have a Catastrophic Impact

3 What’s Causing Global Warming?  Net Heat Input Causes Global Warming Top of Atmosphere  Heat Incoming  Heat Outgoing

4 Where Does the Heat Go?  Net Heat Input to Earth System (Levitus et al., GRL, 2004) 84% -- Saved By The Oceans! Amount of Heat Absorbed by Parts of Earth Climate System Over Past 40 Years

5 Church et al., 2004, 2006 Holgate and Woodworth, 2004 1.8 +/- 0.3 mm/yr (1960 to 2000) Satellite altimetry What is the most obvious consequence ? Mean Sea Level Rise, 1870-2000: ~1.7 mm/yr, with an increase in the rate of rise

6 Altimeter Record of Sea Level Rise Over Past 15 Years

7 Sea Level Rise From Topex & Jason-1: 1993-2007 Sea Level Rise is spatially, highly non-uniform GLOSS Tide Gauges Tide gauges are important, but primarily for altimeter calibration

8 Ice Melt More Water, More Mass   Thermal Expansion, More Volume Heat What’s Causing Sea Level Rise?   Sea Level Rise

9 Sea Level Budget Changes With Time Current Rate Nearly Twice the 20th Century Rate Largely Due to Volume Changes VolumeMassVolumeTotalMassTotal 1920 - 1990 1992 - 2003 0.5 mm/yr 1.8 mm/yr 1.3 mm/yr 1.5 mm/yr 1.7 mm/yr 3.2 mm/yr

10 Sources of Ice Melt & Potential Impact on Sea Level 70 m Antarctica 6 m Greenland 0.7 m Mountain Glaciers

11 The loss poses grave environmental dangers … but not Sea Level Rise … (Archimedes Principle) Summer 1979 Summer 2003 Arctic Sea Ice Is Disappearing At Record Rate

12 Cryospheric sea-level rise: glaciers and ice sheets Konrad Steffen, Steve Nerem,CIRES, Univ. of Colorado Ice Melt Contributions to Sea Level Rise: Glaciers & Ice Sheets Mountain Glaciers Are Currently the Biggest Source, But Probably Not For Long.

13 Greenland Is a Growing Worry Its ice sheets are flowing faster towards the ocean during summer. Possibly due to surface melt water cascading down crevases and providing lubrication at the ice/rock interface.

14 How Is The Ocean Heat Distribution Measured? Argo Profiler Array

15 Courtesy of Mathieu Belbeoch, Argo Information Center * ice-free oceans Starting in 2000, Argo Attained Global Coverage of the Oceans* in Nov 2007

16 How accurate are the projections? IPCC projects sea level to rise ~30-80 cm by 2100 Reconstructed record from tide gauges Satellite altimetry The additional land-ice uncertainty Model projection Rahmstorf et al., Science, 2007 Observed sea level is rising at the upper limit of IPCC TAR projection that includes a “land-ice uncertainty” * 4 th Assessment Report


18 Can We Close the Sea Level Budget?  Jason = +3.6 mm/yr  GRACE = +0.8 mm/yr  Argo = -0.5 mm/yr  Argo + GRACE = +0.6 mm/yr ? Willis, Chambers & Nerem, JGR, 2008 Mass Sea Level Volume Sea Level Total Sea Level

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