Ice in Greenland and Antarctica
Almost all of the world’s ice is found in Greenland and Antarctica, covering about 10% of the global land surface and storing over 70% of the Earth’s freshwater.
The future of these two huge areas of ice is one of the most active and most important areas of research into climate change.
Reliable records for ice depth and extent in Greenland and Antarctica exist only for the last 40 years. There is a much research going on now to try to understand how much ice was present in the past, including the distant past. Measuring the ice now and understanding how the ice has changed in these areas is extremely important because of the potential effects on sea levels and ocean currents if there is widespread and sustained ice melt.
Both Greenland and Antarctica have shown significant melting over the last 50 years, fitting with the rise in global temperature. As a result of the way in which the atmosphere and oceans move heat around the world, temperatures will rise faster at the poles than at the equator.
The Larsen B Ice Shelf
In 2002 the Larson B Ice Shelf suddenly broke up, off the Antarctic Peninsula; 3250 km² of ice broke off, an area almost twice the size of the Isle of Skye. While the Ice Shelf was sea ice and so contributed little to sea level rise it was holding back the land ice. The flow rate of land ice on the peninsula falling into the sea has now increased.
Images and more information on the Larsen B collapse are available at Nasa's Earth Observatory.
The Wilkins Ice Shelf
In April 2009 the Wilkins Ice Shelf broke apart. The Wilkins is following a pattern of instability and rapid collapse that many Antarctic Peninsula ice shelves have experienced in recent years. Scientists think that the dramatic loss of these ice shelves, which have existed for hundreds to thousands of years, is an important sign of climate change in the Southern Hemisphere.
Images and more information on the Wilkins collapse are available at Nasa's Earth Observatory.
Greenland
In Greenland, there have also been recent rapid increases in melting rates on the edges of the ice sheet. This has been accompanied by increased ice sheet thickness at the centre of the island, attributed to increased snow fall.
A major aim of climate change science is to understand what is happening in these areas. While there is evidence that they are melting fast and the process is getting faster, there is still a great deal of doubt about the rates. The answers to these questions are essential if we are to predict how much sea levels will rise due to climate change.