25% Higher Sea Level Rise Than Predicted If West Antarctic Ice Sheet Melts
This is the effect of a 6 meter sea level rise on the southeastern United States, Mexico and the Caribbean. Image: Center for Remote Sensing of Ice Sheets
I don't want to alarm anyone, as there's still debate going on about how much of West Antarctic Ice Sheet will actually melt because of global climate change, but should all of it melt sea level rise in North America and the nations in the southern Indian Ocean is likely to be a bit more than previous estimates indicated: 25% more in fact. Here's why:Sea Level Rise Won't Be Uniform Across the GlobeAccording to new research carried out by geophysicist Jerry Mitrovica, physics grad student Natalya Gomez and geoscientist Peter Clark, if the entire West Antarctic Ice Sheet melts sea level rise will be about 6-7 meters. And, unlike previous estimates which assumed that sea level rise would be evenly distributed throughout the globe, that's too simplified an assumption because of these factors,
1. When an ice sheet melts, its gravitational pull on the ocean is reduced and water moves away from it. The net effect is that the sea level actually falls within 2,000 km of a melting ice sheet, and rises progressively further away from it. If the West Antarctic Ice Sheet collapses, sea level will fall close to the Antarctic and will rise much more than the expected estimate in the northern hemisphere because of this gravitational effect;
2. The depression in the Antarctic bedrock that currently sits under the weight of the ice sheet will become filled with water if the ice sheet collapses. However, the size of this hole will shrink as the region rebounds after the ice disappears, pushing some of the water out into the ocean, and this effect will further contribute to the sea-level rise;
3. The melting of the West Antarctic Ice Sheet will actually cause the Earth's rotation axis to shift rather dramatically - approximately 500 metres from its present position if the entire ice sheet melts. This shift will move water from the southern Atlantic and Pacific oceans northward toward North America and into the southern Indian Ocean.
More: The Sea-Level Fingerprint of West Antarctic Collapse Science Feb 6, 2009 (subscription or pay-per-read required)