Sea Level

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• Sea Level Ice Sheets
• Concern about the Future of Inhabited Coastlines

Presented by Beth Caissie
(thanks to Ken Miller, Rutgers, for many of his
slides)
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Sources Petit et al. (1999) Nature 399, 429-436
and National Oceanic and Atmospheric
Administration (NOAA), USA
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Sea level history over the past 450,000 years
Source Labeyrie et al (2003) In Paleoclimate,
Global Change and the Future, Springer.
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Last interglacial
TODAY
Global Sea Level
Full Glacial
Lambeck et al., 2002, based on tropical
subtropical records
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(No Transcript)
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• Ice from the Ocean makes ice sheets, so sea level
  drops
• When Ice sheets melt, sea level goes up.

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Antarctica
West
East
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Why Is Global Sea Level Rising Today?

• Melting Ice Caps and Glaciers
• Melting land ice adds to ocean volume (sea ice
  does not)
• Greenland is thinning today, but didnt disappear
  during the Last Interglacial

.

• IPCC2001 near 0
• Cazenave Nerem (2004) gt0.15 mm/yr
• Sterns Hamilton (2007) 0.57 mm/y

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Muir Glacier
Why Is Global Sea Level Rising Today?

• Glacial Retreat
• Most glaciers world-wide are in retreat
• Alpine glaciers contribute 0.6 mm/yr to sea level
  rise
• Why are some advancing?
• Increased snow

• 1941, William Field
• 2004, Bruce Molnia

From the Glacier photograph collection. Boulder,
Colorado USA National Snow and Ice Data
Center/World Data Center for Glaciology. http//ns
idc.org/data/glacier_photo/repeat_photography.html

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Why Is Global Sea Level Rising Today?

• Thermal Expansion
• ocean has gained heat
• Warmer water less dense global 20th century
  warming 0.6C
• 1.6 mm/yr sea-level rise

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Should I Sell My Shore House?
Brazil
Atlantic City NJ
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Observations(Tide Gauge and Satellite Altimetry
Data)

• Overall 10-20cm rise in 20th century
• 20th century average rate of sea level rise
  1.70.3mm/yr
• 1950-2000 1.80.3mm/yr
• 1993-2003 accelerated to 3.10.7 mm/yr

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Sea-Level Forecast IPCC 2007
40 cm (1.25 ft) rise by 2100 1 m (3.3 ft) by 2200
IPCC 2007 error 20-60 cm (does not include ice
sheet melting)
2007
http//www.realclimate.org/images/sealevel_1.jpg
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Recent Global Sea Level Rise Estimates
Slide from Rahmstorf web site
Data Church and White (2006) Scenarios 2100 50
140 cm (Rahmstorf 2007) 55 110 cm (high
end, Delta Committee 2008) Scenarios 2200 150
350 cm (high end, Delta Committee
2008) Scenarios 2300 250 510 cm (German
Advisory Council on Global Change, WBGU, 2006)
WBGU
Delta Comm.
Rahmstorf
Data
Best Estimate 80 cm of SL Rise by 2100, 1 m is
not out of the question
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Long Beach Island, NJ
Human stabilized
400 m
Natural movement
Courtesy N. Psuty
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(from Day After Tomorrow)
Sea Level Rise like this? No !
Gradual sea level rise and storm events causing
this? Highly likely!
http//www.learnnc.org/lp/editions/cede_smsandvol/
323
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The Nile River Delta
1 m SL Rise would impact 6.1 Million people
4500 km2 cropland
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Boston
http//www.geo.umass.edu/stategeologist/frame_maps
.htm