Global Sea Level Rise: Laury Miller

Global Sea Level Rise

Laury Miller NOAA Lab for Satellite Altimetry

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

What’s Causing Global Warming?

Heat Incoming

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Heat Outgoing

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Top of Atmosphere

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Net Heat Input Causes Global Warming

Where Does the Heat Go? Amount of Heat Absorbed by Parts of Earth Climate System Over Past 40 Years Net Heat Input to Earth System



(Levitus et al., GRL, 2004)

84% -- Saved By The Oceans!

What is the most obvious consequence? Mean Sea Level Rise, 1870-2000: ~1.7 mm/yr, with an increase in the rate of rise Satellite altimetry

Holgate and Woodworth, 2004 1.8 +/- 0.3 mm/yr (1960 to 2000)

Church et al., 2004, 2006

Altimeter Record of Sea Level Rise Over Past 15 Years

Sea Level Rise From Topex & Jason-1: 1993-2007

GLOSS Tide Gauges

•Sea Level Rise is spatially, highly non-uniform • Tide gauges are important, but primarily for altimeter calibration

What’s Causing Sea Level Rise? Ice Melt

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Heat

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More Water, More Mass

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Thermal Expansion, More Volume

Sea Level Rise

Sea Level Budget Changes With Time Current Rate Nearly Twice the 20th Century Rate Largely Due to Volume Changes

1920 - 1990

1992 - 2003 3.2 mm/yr

1.8 mm/yr 1.3 mm/yr 0.5 mm/yr

1.7 mm/yr 1.5 mm/yr

Sources of Ice Melt & Potential Impact on Sea Level 70 m

6m Antarctica

Greenland

0.7 m Mountain Glaciers

Arctic Sea Ice Is Disappearing At Record Rate

Summer 1979

Summer 2003

The loss poses grave environmental dangers … but not Sea Level Rise … (Archimedes Principle)

Cryospheric sea-level rise: glaciers sheets Ice Melt Contributions to Sea and Levelice Rise: Glaciers & Ice Sheets Sea Level Rise (%) [IPCC, 2006]] 100% = 1.28 mm a-1

Mountain Glaciers Are Currently the Biggest Source, But Probably Not For Long.

Antarctica 10

Sea Level Rise (%) [Meier et al., 2007] 100% = 1.8 mm a-1

Greenland 20

Antarctica 10

Glaciers 70

Greenland 28

Glaciers 62

Sea Level Rise (%) [latest GRACE data)] 100% = 2.2 mm a-1 Antarctica 20

Glaciers 50

Konrad Steffen, Steve Nerem,CIRES, Univ. of Colorado

Greenland 30

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.

How Is The Ocean Heat Distribution Measured? Argo Profiler Array

Starting in 2000, Argo Attained Global Coverage of the Oceans* in Nov 2007

* ice-free oceans

Courtesy of Mathieu Belbeoch, Argo Information Center

How accurate are the projections? IPCC projects sea level to rise ~30-80 cm by 2100

Reconstructed record from tide gauges

Satellite altimetry

Model projection

The additional land-ice uncertainty

Observed sea level is rising at the upper limit of IPCC TAR projection that includes a “land-ice uncertainty” * 4th Assessment Report

Rahmstorf et al., Science, 2007

Can We Close the Sea Level Budget? Total Sea Level

Jason = +3.6 mm/yr  Argo + GRACE = +0.6 mm/yr

?

Volume Sea Level  Argo = -0.5 mm/yr Mass Sea Level  GRACE = +0.8 mm/yr Willis, Chambers & Nerem, JGR, 2008