Saturday, August 27, 2016

Global Warming Is Melting the Greenland Ice Sheet, Fast

Greenland Ice Sheet. (Photograph Credit: Briggs/CPOM) Click to Enlarge.
Measuring ice sheet melting is important, not only as a signal of global warming but also because of the sea level impacts.  But how is this melting measured?  The ice sheets on Greenland and Antarctica are huge and scientists need enough measurements in space and time to really understand what’s going on.  That is, we need high-resolution and long duration measurements to fully understand trends.

In a very recent publication in the journal Geophysical Research Letters, an international team reported on a new high-resolution measurement of Greenland.  The lead author, Malcolm McMillan from the Center for Polar Observation and Modeling, and his colleagues mapped Greenland with incredibly high resolution (5 km distances).

They accomplished this mapping by obtaining data from the Cryosat 2 satellite.  This satellite uses a technique called laser altimetry to measure the height of surfaces.  It is able to track the elevation of the ice sheets on Greenland with high precision.  If the height of the ice sheet is growing, it means the ice is getting thicker. If the heights are decreasing, it means the ice layers are getting thinner.
The authors of this study ... discovered that not only is Greenland losing a lot of ice, but the loss varies a lot depending on location and year.  For example, 2012 was a year of incredible ice loss compared to other years.  Also, the western side of the ice sheet is losing much more ice than the eastern side.  They also found that a small part of the ice sheet (less than 1% of the sheet) is responsible for more than 10% of the mass loss.

In total, they estimate approximately 270 gigatons of ice loss per year for 2011–2014.  This result is almost a perfect match to independent measurements made by other researchers and builds our confidence in their conclusions.  To put this in perspective, the Greenland Ice Sheet is losing approximately 110 million Olympic size swimming pools worth of water each year.

Read more at Global Warming Is Melting the Greenland Ice Sheet, Fast

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