Polar Ice Sheets Vulnerable Even with Moderate Global Warming
18.12.2009 - Ice & Snow, Bi-polar
A new study authored by Dr. Robert Kopp entitled "Probabilistic Assessment of Sea Level during the Last Interglacial Stage", was conducted by scientists at Princeton and Harvard Universities and published in Nature. It employs a new statistical approach to show that the Earth's polar ice sheets are vulnerable even to moderate global warming.
If greenhouse gases are not diminished and the climate becomes just 2°C warmer, sea level rise could reach up to 6 to 9 meters in the long term. Such a rise would flood low-lying coastal areas around the world, including Louisiana, southern Florida, much of Bangladesh, and most of the Netherlands.
For the study, the researchers compiled an extensive database of geological sea level indicators for the last interglacial stage that occurred some 125,000 years ago. Polar temperatures at that time were 3 to 5°C warmer than today - as is expected to occur in the future if temperatures reach about 2 to 3°C above pre-industrial levels.
Because they provide a historical analog for a future with a fairly moderate amount of warming, sea levels during the last interglacial period are of particular interest. And because they are fairly recent by geological standards, they allow climate scientists to develop a credible sea level record for a period when average global and polar temperatures were somewhat higher than today.
What's more, through their analysis, researchers showed that there is a 95 percent probability that, during the last interglacial stage, global sea level peaked more than 6.6 metres above its present level, and possibly as much 9.4 metres. The findings further indicate that this rise occurred at least two to three times faster than current rates, and that both the Greenland and West Antarctic ice sheet shrank significantly and contributed to sea level rise.
Although previous geological studies of sea level benchmarks have shown that local sea levels during the last interglacial stage were higher than today, they differ from those in this earlier stage. The major contributing factor being that the changing masses of the ice sheets alter the planet's gravitational field and deform the solid Earth.
