Sea Level Ice Sheets Concern about the

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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)

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 • • IPCC 2001: 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 20 th 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 -20 cm rise in 20 th century • 20 th century average rate of sea level rise: 1. 7± 0. 3 mm/yr • 1950 -2000 1. 8± 0. 3 mm/yr • 1993 -2003 accelerated to 3. 1± 0. 7 mm/yr

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 Data 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 km 2 cropland

Boston http: //www. geo. umass. edu/stategeologist/frame_maps. htm

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