Greenland Ice sheet
CLIMATE EMERGENCY INSTITUTE
The Health and Human Rights Approach to Climate Change
The biggest effect of global warming that is most often referred to by scientists as our biggest climate change is the change in the state of the Greenland ice sheet, whereby its instability and enormous size makes its total loss slipping into the sea unstoppable and irreversible. The result is a large rise in coastal sea levels.
Because of the extremely long time frames involved in this change we do not regard this one of our top concerns. However with every new research finding the time frame is diminishing.
While complete loss of all ice in Greenland is judged to be extremely unlikely during this century, the melting is accelerating, with a record extent of surface melting in the past decade.
Sept 2014 Greenland Ice Sheet more vulnerable to climate change than previously thought
A new study finds that the Greenland Ice Sheet, which covers 1.7 million square kilometers and contains enough ice to raise sea levels worldwide by seven meters, is less stable and more sensitive to climate change than previously thought.
The Greenland Ice Sheet, which is the second-largest ice sheet in the world, covers 1.7 million square kilometres -- an area roughly eight times the size of the United Kingdom -- and contains enough ice to raise sea levels by more than seven metres if it were to be lost altogether.
Currently, due to surface melting alone, it is losing ice at a net annual rate of 200 gigatonnes, equating to 0.6 millimetres of sea level rise.
Large ice sheets such as in Greenland are far from stationary. Different parts of the ice often move at different speeds, causing ice to shear, a phenomenon known as ice flow.
"When these large ice sheets melt, whether that's due to seasonal change or a warming climate, they don't melt like an ice cube," said Dr Marion Bougamont of Cambridge's Scott Polar Research Institute, who led the research. "Instead, there are two sources of net ice loss: melting on the surface and increased flow of the ice itself, and there is a connection between these two mechanisms which we don't fully understand and isn't taken into account by standard ice sheet models."
Whereas other models of the Greenland Ice Sheet typically assume the ice slides over hard and impermeable bedrock -- an assumption which is largely practical and based on lack of constraints -- this study incorporates new evidence from ground-based surveys, which show soft and porous sediments at the bed of the ice sheet, more like the soft and muddy bottom of a lake than a sheet of solid rock. The new study specifically identifies the intake and temporal storage of water by weak sediment beneath the ice sheet as a crucial process in governing the ice flow.