New Data May Change Sea Level Rise Assessments

For many years, scientists have believed that warmer temperatures over the summer would speed up the flow of glaciers from ice shelves into the sea. But new satellite data collected by an European spacecraft show that this is not the case, and that warm weather actually slows down the glaciers.

Investigators were equally as surprised when they learned about this correlation, but say that this is the conclusion the new information point at. The datasets were collected by the oldest environmental satellite Europe operates.

The ERS-1 satellite was launched by the European Space Agency (ESA), and it is about to turn 20 years-old this July. Data it collected over the years has been used in a variety of past studies.

Researchers recently turned their eyes to Greenland, one of the largest reserves of ice in the Northern Hemisphere, the second following the North Pole. Previous studies have determined that the island was losing its ices at an accelerated pace.

One of the causes experts identified for this was the higher atmospheric temperatures the continent was exposed to. The heat melted the surface of the ice sheets, and then triggered the formation of moulins.

These are structures similar to tunnels at the surface of the Greenland ice shelf, which conduct warmer meltwater from the surface down to the bedrock underneath. As the water reaches the rocks, it creates a lubricated layer on which the glacier slip towards the ocean.

For quite some time now, experts have been trying to determine how is it that this phenomenon influences the acceleration of ice flow during the summer months. Their inability to do so has been damaging climate models ever since.

As a side effect, projections on the future of global sea level rise were also kept stagnant. Now, the new study promises to break this deadlock, and finally allow for more accurate climate modeling.

In a research paper appearing in this week's issue of the top scientific journal Nature, experts say that the increased melt rates actually slow down glacier flows during the summer. Experts suggest that Greenland's plumbing is capable of handling the extra water without speeding up glaciers.

“It had been thought that more surface melting would speed up flow and cause the ice sheet to retreat faster, but our research suggests the process is more complicated,” says University of Leeds professor Andrew Shepherd.

“We used ERS-1 data and a technique called 'intensity tracking' over periods of 35 days to estimate the speed at which the glaciers were moving throughout the study,” the expert explains.

“Our research suggests that increases in surface melting may not change the rate of flow at all. However, this doesn't mean that the ice sheet is safe from climate change because changes in ocean melting also play an important role,” he goes on to say.