Greenland’s glaciers aid sea level forecasts

Research into Greenland’s glaciers will help forecasts of sea level rise – which are key to preparing for the impact of climate change.

A team of scientists, including researchers from Edinburgh, has taken an important step towards improving these predictions.

Estimating how quickly the Greenland Ice Sheet will shrink as the climate warms has proved difficult, owing to a poor understanding of the rapid changes that occur where the ice sheet meets the ocean.

Long-term change

The latest study found that, while glacier retreat could appear unpredictable when studied over a few years, the relationship between the rate of retreat and warming was clearer over longer timescales.

Crucially, it found that variations in ocean temperature help to explain key discrepancies in glacier retreat along Greenland’s east coast.

The ice sheet, which contains enough water to raise sea levels by around seven metres if it melts completely, is expected to be a major source of sea level rise over the coming centuries.

Satellite study

Research led by the University of St Andrews in collaboration with the Universities of Sheffield, Edinburgh, Cambridge and California San Diego, examined the behaviour of 10 large glaciers in east Greenland over the 20-year period to 2012, using satellite imagery to track their retreat.

In south-east Greenland, major glaciers retreated by several kilometres between 2000 and 2005 as regional air temperatures warmed rapidly.

Contrastingly, glaciers in the north-east remained much more stable, despite air temperatures warming by a similar amount.

The team attributed this disparity to very cold ocean waters along the coast of north-east Greenland.

Iceberg formation

Warmer ocean waters melted the submerged parts of glaciers, encouraging undermined blocks to tumble into the sea as icebergs.

Colder waters suppress this process, which may then make glaciers more resilient to the warming air temperatures.

These findings will be crucial in helping predict the rate of mass loss from the Greenland Ice Sheet over the coming century.

The study, supported by the Natural Environment Research Council, was published in Proceedings of the National Academy of Sciences.

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