Greenland Ice News Not All Thawed Out Yet
Jul 30, 2012
posted in: Office
USF professor tempers our initial shock.
If you’ve seen recent NASA photos of surface ice melt, chances are you were shocked. While these new images are distressing, USF associate professor Dr. Don Chambers says it may be a while before we have enough information to figure out what this increased surface-area melting really means. He believes we must first understand, how much ice is melting and where the ice is going?
A brief summary of his reaction is below:
The measurements of the large surface area of summer melt are quite interesting, but it will be a few months before we can determine whether this led to increased runoff and mass loss for the Summer melt season. Another NASA/German satellite mission, the Gravity Recovery and Climate Experiment (GRACE), can detect the total mass lost from Greenland every month, and these data will give us a better perspective on what has happened.
Over the last 10 years, the amount of mass being lost during the Summer has far surpassed the amount gained during the Winter growth season, and has been accelerating. However, most of this mass loss has come from surface melt along the fringes of the ice sheet and retreat of glaciers. There has been very little mass loss, and perhaps some gain, in the interior, which is where the unusual surface melting has been observed.
The surface melt measurements merely indicate melt, but not the actual amount of melt (i.e., how much ice/snow melted). It’s possible (especially at the higher altitudes of the interior) that the melted ice/snow will form pools that can refreeze later this winter. On the other hand, it may run off through moulins (a near vertical shaft through the glacier) either to the sea, or to other parts of the glacier or to the boundary between the ice sheet and the bedrock. Time will tell, and we should be able to detect any significant change from the gravity measurements in the next few months.
Also, from what I understand by reading news reports and comments by several scientists who are more expert on surface melting, this is uncommon, but has happened before and more than than once. It’s kind of like landfalling hurricanes hitting Pinellas County - it doesn’t happen every year, but it has happened before and it is always possible any season.
Dr. Chambers specializes in using satellite observations such as radar altimetry and satellite gravimetry to better understand ocean dynamics. His primary research focus is quantifying and understanding sea level variability, especially low frequency fluctuations related to climate change. He is interested in all the dynamical processes that cause sea level change, including ocean circulation, ocean heat storage, ocean mass redistribution, and influx of fresh water from the continents and ice sheets.
For more information on Dr. Chambers work, visit http://www.marine.usf.edu/faculty/don-chambers.shtml
Illustration courtesy Nicolo E. DiGirolamo and Jesse Allen, © NASA