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Greenland studies aid sea level forecast

Edinburgh scientists have helped allay fears over the rate of decline of Greenland’s ice sheet, in two new studies.

Researchers have helped show that meltwater draining beneath glaciers will not have a significant impact on rising sea levels.

Knowing how fast the ice sheet will flow under warmer climatic conditions as it melts in summer and re-freezes in winter is important for predicting its future contribution to sea level rise.

Minimal impact

In one study, the researchers found that the annual movement of parts of the Greenland Ice Sheet is only minimally affected by increased melting.

The team found that generally faster ice movement in warmer summers is cancelled out by slower motion the following winter.

Inter-annual and seasonal changes in the characteristics of the drainage system beneath the ice sheet determine how slippery the ice sheet base becomes, and how fast the ice moves.

GPS tracking

Professor Pete Nienow and colleagues from Edinburgh together with scientists from the Universities of Sheffield, Aberdeen and Newcastle gathered detailed ice flow data using differential Global Positioning Systems and ice surface melt rates along a 115 km transect in west Greenland from 2009 to 2011.

The study, supported by the Natural Environment Research Council, was published in the journal Geophysical Research Letters.

Glacier flow

In a separate modelling study, the field data collected by the Edinburgh scientists was used to show that meltwater’s lubricating effect on glacier flow is likely to play only a minor role in contributing to sea level rise.

Researchers had been concerned that meltwater flowing between the glacier and the land would act as a lubricant, and accelerate glacier movement.

Field data

However, the computer modelling study, led by scientists at the University of Bristol and based on field data from Greenland, has shown that this increased slippiness will add a maximum of 8mm to sea level rise by 2200.

This represents less than five per cent of the total projected contribution from the Greenland ice sheet.

The study, carried out through the European funded Ice2sea programme (www.ice2sea.eu), was published in Proceedings of the National Academy of Sciences.

These findings improve our understanding of the behaviour of the Greenland Ice Sheet and reduce the error in estimating its likely contribution to sea-level rise in a warming world.
Professor Pete NienowSchool of GeoSciences