Greenland Ice Sheet is melting

5616According to www.theguardian.com, a new study measures the loss of ice from one of world’s largest ice sheets. The emission of heat-trapping gases results in major changes to the Earth, one of which is melting ice. This includes ice atop mountains, ice floating in cold ocean waters, and the ice within large ice sheets or glaciers. The last type of ice loss raises sea level as a result of water running into the ocean. However, melting sea ice has small chances to affect sea level as it is already floating in ocean waters. So 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 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 and his colleagues mapped Greenland with incredibly high resolution. They accomplished this mapping by obtaining data from the Cryosat 2 satellite which uses a special technique to measure the height of surfaces. 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.
A simplistic view would be that if ice sheets become taller, then they contain more frozen water. If they are shorter, they contain less water. But, this isn’t the entire story. Scientists also have to account for other changes, such as changes to density, surface roughness, and water content.
This study has shown that that not only is Greenland losing a lot of ice, but the loss varies a lot depending on location and year. In total, they estimated approximately 270 gigatons of ice loss per year for 2011–2014.
Lead author Malcolm said the study held allowed them to understand where and when the greatest ice losses have occurred, the extent of Greenland’s contribution to sea level in recent years and how much ice has been lost each year.
The duration of this study is pretty short (4 years). It is interesting to see if the mass loss continues at the same rate in following years. If it happens, it would be bad news for vulnerable coastal cities like Miami.

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