The blue areas in this image represent changes in elevation of the ice sheet from 2003-2006; the grey areas represent no change in elevation. Image: NASA Goddard Photo and Video/Creative Commons.
We've all heard that the Greenland Ice Sheet is melting and that should it disappear completely some really dramatic sea level rise will occur. Some new research sheds some light on what's causing the most melting, and it's not the gradually warming temperatures we're currently experiencing. Rather, it's short-term weather extremes doing the most damage. Either way it's still climate change.The new research, published in the journal Nature, shows that steady meltwater caused by gradual warming actually may slow down glaciers' flow towards the ocean, but sudden increases in water caused by weather extremes are driving the observed increase in melting.
Christian Schoof, from the University of British Columbia and the study's author, explains that steady flows of meltwater can be accommodated by existing channels under the Ice Sheet, but rapid flows cannot:
The conventional view has been that meltwater permeates the ice from the surface and pools under the base of the ice sheet. This water then serves as a lubricant between the glacier and the earth underneath it, allowing the glacier to shift to lower, warmer altitudes where more melt would occur.
Sudden water input caused by short term extremes, such as massive rain storms or the draining of a surface lake, however...allows [the meltwater] to pool and lubricate the bottom of the glaciers and accelerate ice loss. (Science Daily)
So, the basic conventional view of how the glacier moves towards the sea is correct, but the impetus for that movement is different based on Schoof's findings.
Either way, as Schoof also points out, climate change is causing both the gradual warming and the short-term weather extremes.
Read the original research: Ice-sheet acceleration driven by melt supply variability [subscription or pay-per-read required]
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More on Global Climate Change:
Greenland Ice Cover Loss Shown With New Earth-Space Monitoring System (Video)
Greenland Glacier About to Lose Manhattan-Sized Ice Chunk (Video)
Greenland Glacier Retreats One Mile Overnight! NASA Shows Satellite Photos
Two Meter Sea Level Rise Now Inevitable - But How Fast Will It Happen?