Greenland’s peripheral glaciers, those that are not directly connected to the primary ice sheet, are contributing much more to global sea-level rise than was previously thought. Researchers discovered that these peripheral glaciers, while only making up 5-7 % of total ice coverage on the land mass, are causing up to 20% of the rise in sea level created by the Greenland’s melting.
This new finding is important as it should lead to more accurate predictions of how Greenland’s ice sheet will behave in the future, and affect sea levels.
The research was done “using lasers which measure the height of the ice from space, and a recently completed inventory of Greenland’s glaciers and ice caps.” With these, the researchers “were able to determine changes in the mass of those ice bodies, separate from the main ice sheet.”
“It also showed that the contribution to sea-level rise from the glaciers of Greenland separated from the ice sheet makes up around 10% of the estimated contribution of the entire world’s glaciers and ice caps, and that contribution is higher than expected.”
Lead author Dr. Tobias Bolch, from the University of Zurich, says, “The melting of ice on Greenland is known to be one of the major sources for global sea-level rise. Beside the large ice sheet, there are thousands of peripheral glaciers which are not connected to the ice sheet or can be separated from it due to the existence of ice divides. The area of those glaciers is about 50 times higher than the ice cover of the European Alps. Consequently, it is important to investigate not only the ice sheet but also these local glaciers.”
The new research found that glaciers that had no connection or weak connections to the primary ice sheet “contributed to around 30 Gigatons (Gt) of water per year to sea level between 2003 and 2008.”
“When they added in glaciers which had some link to the ice sheet, but which were still distinct from it in the way they flowed, this figure increased to up to around 50 Gt per year. This yearly figure represents more than half the water contained in one of Europe’s largest lakes, Lake Geneva.”
“The study gives more detail to the make-up and stability of Greenland’s glaciers showing that mass loss is highest in the warmer south east of the land mass and lowest in the colder north.”
“It also shows that the loss of ice is about 2.5 times higher for those separate glaciers than for the ice sheet, leading to the 15-20% figure.”
Dr. Bolch says, “The other 80-85% comes from the ice sheet. The new figure for the local glaciers is higher than expected. It matters because the ice loss with respect to the area is significantly higher than of the ice sheet. This means that the local glaciers react faster with respect to climate change. This information will help to improve the predictions of the future contribution of Greenland’s ice to sea-level rise.”
Image Credits: Landsat ETM; image editing: Tobias Bolch (University of Zurich)