Washington: A new study has suggested that melt-water that trickles down through the ice is likely to have a minor role in sea-level rise compared with other effects like iceberg production and surface melt.
Previously, scientists had feared that melt-water could dramatically speed up the movement of glaciers as it acts as a lubricant between the ice and the ground it moves over.
A team led by scientists from the University of Bristol found through the results of computer modelling, based on fieldwork observations in Greenland that by the year 2200 lubrication would only add a maximum of 8mm to sea-level rise - less than 5 per cent of the total projected contribution from the Greenland ice sheet.
In fact in some of their simulations the lubricating effect had a negative impact on sea-level rise - in other words it alone could lead to a lowering of sea-level.
Lead author, Dr Sarah Shannon, from the University of Bristol, said that this is an important step forward in our understanding of the factors that control sea-level rise from the Greenland Ice Sheet.
She said that their results showed that melt-water enhanced lubrication will have a minor contribution to future sea-level rise.
Shannon asserted that future mass loss will be governed by changes in surface melt-water runoff or iceberg calving.
Previous studies of the effects of melt-water on the speed of ice movement had assumed the water created cavities at the bottom of ice masses. These cavities lifted the ice slightly and acted as a lubricant, speeding up flow.
This theory had led scientists to think that increased melt-water would lead directly to more lubrication and a consequent speeding up of the ice flow.
The scientists found that no matter whether more melt-water increases or decreases the speed of ice flow, the effect on sea level is small.
Shannon said that her team found that the melt-water would lead to a redistribution of the ice, but not necessarily to an increase in flow.
The findings have been published in Proceedings of the National Academy of Sciences.