Warmer summers are causing Antarctic ice shelves to 'bend'

Warmer summers are causing Antarctic ice shelves to 'bend' and buckle under the weight of increased water that puts huge pressure on surface lakes, new research has shown. 

The latest study shows a direct link between surface melting and the weakening of Antarctic ice shelves, the first of its kind to be conducted in the field.

The formation and draining of lakes that come from ice and snow melting can cause a floating Antarctic ice shelf to 'flex' and destabilise, scientists say.

The extra pressure creates indents in the ice if sufficiently large, and subsequent draining process can then create so much stress that lake basins can weaken and break. 

Warmer summers are causing Antarctic ice shelves to 'bend' and buckle under the massive weight of increased water in surface lakes, warns new research. The filling and draining of meltwater lakes has been found to cause a floating Antarctic ice shelf to flex, potentially threatening its stability

Warmer summers are causing Antarctic ice shelves to 'bend' and buckle under the massive weight of increased water in surface lakes, warns new research. The filling and draining of meltwater lakes has been found to cause a floating Antarctic ice shelf to flex, potentially threatening its stability

A team of researchers led by Cambridge University scientists has measured how much the McMurdo ice shelf in Antarctica flexes in response to the filling and draining of meltwater lakes on its surface.

Meltwater lakes can contain water weighing 50,000 to two million tons each, 

While the 'flexing' of the ice shelf had been simulated before by computer models, it is the first time the phenomenon has been measure in the field.     

The findings also show a link between surface melting and the weakening of Antarctic ice shelves.

They study also suggests that recent ice shelf break-ups around the Antarctic Peninsula may have been triggered by large amounts of surface meltwater produced as a result of atmospheric warming.

As the climate continues to warm over the coming century, more and more ice shelves may become susceptible to flex, fracture and break-up.

Most of the continent is covered by the Antarctic Ice Sheet, which is up to 2.5 miles (4 km) thick and contains enough ice to raise global sea levels by about 58 metres (190 feet).

Over most of the continent and for most of the year, air temperatures are well below zero and the ice surface remains frozen.

But around 75 per cent of the ice sheet is fringed by floating ice shelves, which are up to a kilometre (3,280 ft) thick, mostly below sea level, but with several metres of their total height protruding above the water.

In the summer months, when air temperatures rise above freezing, the surfaces of the ice shelves are susceptible to melting.

Study co-author Dr Ian Willis, of Cambridge's Scott Polar Research Institute (SPRI), said: 'Surface water on ice shelves has been known about for a long time.

'Over 100 years ago, members of both Shackleton's Nimrod team and the Northern Party team of Scott's British Antarctic Expedition mapped and recorded water on the Nansen Ice Shelf, around 300 kilometres from where we did our study on the McMurdo Ice Shelf.

'For the last few decades, it has also been possible to see widespread surface meltwater forming on many ice shelves each summer from satellite imagery.'

He said what is not fully known is the extent to which surface water might destabilise an ice shelf, especially in warmer summers when more meltwater is produced.

If the slope of the ice shelf is sufficiently steep, Dr Willis says the water may flow off the ice shelf to the ocean in large surface rivers, mitigating against any potential instability.

The danger comes if water pools up in surface depressions on the ice

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