Melting Antarctic Ice Sheets Thinning at ‘Extraordinary’ Rate



New research shows that ice sheets deep inside Antarctica have lost up to 100m of their thickness in some places. Known as the West Antarctic ice sheet, it was stable as recently as 1992, and rapid melting is now spreading deeper into the Antarctic interior.

The study published in the scientific journal Geophysical Research Letters compared weather information with 800m satellite measurements of the ice sheet. This enabled the researchers to distinguish between varying snowfall from short term weather changes and the long-term changes caused by climate, the Guardian reports.

From a stable ice sheet at the beginning on the 1990s, thinning has spread progressively inland and in some ice streams have extended 300 miles inland along their 600-mile length.

“More than 50% of the Pine Island and Thwaites glacier basins have been affected by thinning in the past 25 years. We are past halfway and that is a worry,” said Prof Andy Shepherd, of Leeds University in the UK, who led the study.
Scientists already knew that a large amount of ice was being lost from West Antarctica, but now know exactly how much is being lost and how quickly.

It was Cooler in the 90s

Up until recently, snow falling on Antarctica’s glaciers inland balanced the ice loss from icebergs melting and falling into the ocean, but now the glaciers are flowing faster into the sea than snow can replenish them.

The water in the Ocean just in front of glaciers is too hot and therefore causes the underside of the glaciers to melt where they are in contact with the seabed. This melting lessens the grinding effect of friction and the glaciers then slide into the ocean much faster than they normally would.

Separate research published in January found that ice loss from the entire Antarctic continent, not just the western ice sheet, had increased six times since the 1980s. Melting from West Antarctica has already resulted in a 5mm sea rise since 1992.

“Before we had useful satellite measurements from space, most glaciologists thought the polar ice sheets were pretty isolated from climate change and didn’t change rapidly at all. Now we know that is not true,” said Professor Shepherd.

If the Western Antarctic ice sheet melted completely it would result in a five-meter sea level rise, while the much larger East Antarctic Ice Sheet contains enough ice to raise sea levels by a further 60 metres, meaning most coastal cities would be submerged.

Without a dramatic cut in carbon emissions, melting ice and sea level rises will continue for thousands of years and the earth may reach a point where they are impossible to reverse.