Transcript 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)

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)
Sources: Petit et al. (1999) Nature 399, 429-436 and National Oceanic and
Atmospheric Administration (NOAA), USA
Sea level history over the past 450,000 years
Source: Labeyrie et al (2003) In: Paleoclimate, Global Change and the Future, Springer.
Last interglacial
Full Glacial
Global Sea Level
Lambeck et al., 2002, based on tropical & subtropical records
TODAY
Ice from the
Ocean makes
ice sheets, so
sea level
drops
When Ice
sheets melt,
sea level
goes up.
Antarctica
West
East
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 didn’t disappear during the Last Interglacial
•
•
IPCC2001: near 0
Cazenave & Nerem (2004): >0.15 mm/yr
•
Sterns & Hamilton (2007): 0.57 mm/y
Why Is Global Sea Level Rising Today?
Muir Glacier
1941, William Field
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
2004, Bruce Molnia
From the Glacier photograph collection. Boulder, Colorado USA: National Snow and Ice Data Center/World Data Center for Glaciology.
http://nsidc.org/data/glacier_photo/repeat_photography.html
Why Is Global Sea Level Rising Today?
Thermal Expansion:
• ocean has gained heat
• Warmer water less dense global 20th century warming
~0.6°C
• 1.6 mm/yr sea-level rise
Should I Sell My Shore House?
Brazil
Atlantic City NJ
Observations
(Tide Gauge and Satellite Altimetry Data)
•Overall 10-20cm rise in 20th century
•20th century average rate of sea level rise: 1.7±0.3mm/yr
•1950-2000 1.8±0.3mm/yr
•1993-2003 accelerated to 3.1±0.7 mm/yr
Fi g ur e 5 . 1 3
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
Recent Global Sea Level Rise Estimates
WBGU
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)
Delta Comm.
Slide from Rahmstorf web site
Best Estimate = 80 cm of SL Rise by 2100, 1 m is not out of the question
Long Beach Island, NJ
Human stabilized
Natural movement
400 m
Courtesy N. Psuty
(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
The Nile River Delta
1 m SL Rise would impact
6.1 Million people
4500 km2 cropland
Boston
http://www.geo.umass.edu/stategeologist/frame_maps.htm