Tuesday, July 7, 2009

Sea Level Rise: It's Worse Than We Thought

I just read an interesting on-line article from the New Scientist that discusses this. As the article states:

In its 2007 report, the Intergovernmental Panel on Climate Change (IPCC) forecast a sea level rise of between 19 and 59 centimetres by 2100, but this excluded "future rapid dynamical changes in ice flow".

The rest of the fairly extensive article discusses the various types of modeling being done, much of it after the IPCC statement. As is often with such modeling, there is a great deal of uncertainty with complicated system such as the earth including how much greenhouse gas the world produces. However, the conclusion is that the sea level is likely to rise something between 0.8-2.0 meters by 2100 (and of course still increasing in subsequent years).

Sea level rise comes from a number of factors. To briefly mention a few from the article:
- Thermal expansion of water
- Glacier movement of ice into the sea from land
- Melting of surface water on the glacier tunneling beneath to lubricate the glacier movement.
- Surface melting on glaciers creating giant "ice cubes" which may tumble over increasing glacier flow rate
- Warmer sea water near the ice sheets melting from below releasing more dammed ice to increase flow off land

The author also points out that such a rise is consistent with geologic history. There have been instances where sea level has risen by 1.6 meters on average in a 100 year stretch during the last interglacial period and one report that suggests that sea level had risen by 3 meters in 50-100 years.



susane said...

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