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Category 6 has moved! See the latest from Dr. Jeff Masters and Bob Henson here.Connecticut-sized ice shelf disintegrating in Antarctica
A large ice sheet on the Antarctic Peninsula has begun to disintegrate in spectacular fashion over the past four weeks, according to a press release today from the National Snow and Ice Data Center. They attribute the event to strong warming due to climate change. The victim is the Connecticut-sized Wilkins Ice Shelf (5,200 square miles), located about 1,000 miles south of the southern tip of South America. The nearby Larsen B Ice Shelf, which was about three times smaller than the Wilkins Ice Shelf, disintegrated in just three days in 2002. The Larsen B Ice Shelf was several thousand years old, and the Wilkins Ice Shelf is at least several hundred years old. It began disintegrating on February 28, and has just a narrow 6 km wide strip of ice holding it together.
Figure 1. Disintegrating ice from the Wilkins Ice Shelf forms huge blocks in the Bellingshausen Sea by the Antarctic Peninsula. Satellite image from March 8, 2008, courtesy of the National Snow and Ice Data Center.
Sea level rise due to antarctic melting
The disintegration of the Wilkins Ice Shelf will not significantly alter global sea level, since the ice is already floating in the ocean. Some Antarctic ice shelves are important because of their ability to insulate and buttress glaciers along the coast, and their loss allows more rapid melting of the glaciers they hold back. However, this is not the case for the Wilkins Ice Shelf. Its disintegration is of note because the shelf had been around hundreds of years, and is a spectacular sign that the climate is changing.
Melting of ice in the Antarctic Peninsula and along the ocean edges of the West Antarctic Ice Sheet is contributing to about 0.5 mm/year of sea level rise to the world's oceans, according to a NASA study published in February 2008. This is up from the 0.3 mm/year of sea level rise Antarctica contributed in 1996. Melting from the Greenland Ice Sheet also contributes about 0.5 mm/year to global sea level rise. Melting ice from Greenland and Antarctica each contribute about 10-15% of the observed 3-4 mm/year of global sea level rise.
Antarctic temperatures
While most of Antarctica cooled during the period 1981-2004, the Antarctic Peninsula where the Wilkins Ice Shelf lies warmed by about 1° C. Sea Surface Temperatures (SSTs) also warmed by about 1° C near the Antarctic Peninsula, and these warmer waters may be primarily responsible for the disintegration of the shelf. In the period 2005-2007, almost all of Antarctica warmed, canceling out much of cooling observed during 1981-2004 (Figure 2). I explained in detail in a November 2007 blog why most of Antarctica cooled up until the past few years.
Figure 2. Antarctic surface temperatures as observed via AHVRR satellite measurements between 1981 and 2007. Note that the Antarctic Peninsula where the Wilkins Ice Shelf lies has seen the strongest warming. Image credit: NASA
Jeff Masters
Figure 1. Disintegrating ice from the Wilkins Ice Shelf forms huge blocks in the Bellingshausen Sea by the Antarctic Peninsula. Satellite image from March 8, 2008, courtesy of the National Snow and Ice Data Center.
Sea level rise due to antarctic melting
The disintegration of the Wilkins Ice Shelf will not significantly alter global sea level, since the ice is already floating in the ocean. Some Antarctic ice shelves are important because of their ability to insulate and buttress glaciers along the coast, and their loss allows more rapid melting of the glaciers they hold back. However, this is not the case for the Wilkins Ice Shelf. Its disintegration is of note because the shelf had been around hundreds of years, and is a spectacular sign that the climate is changing.
Melting of ice in the Antarctic Peninsula and along the ocean edges of the West Antarctic Ice Sheet is contributing to about 0.5 mm/year of sea level rise to the world's oceans, according to a NASA study published in February 2008. This is up from the 0.3 mm/year of sea level rise Antarctica contributed in 1996. Melting from the Greenland Ice Sheet also contributes about 0.5 mm/year to global sea level rise. Melting ice from Greenland and Antarctica each contribute about 10-15% of the observed 3-4 mm/year of global sea level rise.
Antarctic temperatures
While most of Antarctica cooled during the period 1981-2004, the Antarctic Peninsula where the Wilkins Ice Shelf lies warmed by about 1° C. Sea Surface Temperatures (SSTs) also warmed by about 1° C near the Antarctic Peninsula, and these warmer waters may be primarily responsible for the disintegration of the shelf. In the period 2005-2007, almost all of Antarctica warmed, canceling out much of cooling observed during 1981-2004 (Figure 2). I explained in detail in a November 2007 blog why most of Antarctica cooled up until the past few years.
Figure 2. Antarctic surface temperatures as observed via AHVRR satellite measurements between 1981 and 2007. Note that the Antarctic Peninsula where the Wilkins Ice Shelf lies has seen the strongest warming. Image credit: NASA
Jeff Masters
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