Climate Change in the Arctic - The Changing Arctic Environment: The Arctic Messenger - page 278

given in Washington in March 2011, Mitrovica presented a study (see also the Tamisiea
reference) that concludes that if the Greenland ice sheet catastrophically collapses, the loss
of ice mass would relax the gravitational pull of the ice sheet on the surrounding sea. The
result would be an astonishing 100-metre drop in sea level around Greenland.
Not many scientists presently expect the Greenland ice sheet to catastrophically col-
lapse.Therefore,amorerealisticscenariopresentedbytheMitrovicateamisfortheGreen-
landicesheettomelttotheextentthatitwouldleadtotheequivalentofa1-metreelevation
of mean global sea level. In this case, they estimate that depression in the sea level around
Greenland could be 20-25metres and that the hinge line would again extend from Scotland
northwards. Of course, if sea level is depressed at high northern latitudes, then elevations
above the mean would have to happen far from Greenland.
Thesamemethodscanbeusedtostudytheimpactofothersourcesofmeltingice.The
studies reported by Tamisiea and by Mitrovica on melting of the West Antarctic ice sheet
showed that the Pacific and Atlantic coasts of North America would experience a substan-
tial enhancement of sea level rise, with only the extreme tip of South America enjoying the
benefit of sea level depression. Each such study shows a unique geographical pattern of sea
level elevation and depression, known as a sea level fingerprint .
To sum up this entire section, the Arctic Messenger is telling the world that the Green-
land ice sheet, along with the Arctic mountain ice caps and glaciers, is losing significant
proportions of its mass to the ocean. The Arctic landscape is changing dramatically before
the eyes of those who live in these regions. But the Arctic Messenger is also telling us that
if we live close to sea level (and many of us do), we need to pay very close attention to
the rate of melting of the Greenland and West Antarctic ice sheets and of mountain glaci-
ers wherever they may be. It is a paradox that studies on gravitational tides around the two
large ice sheets suggest that the greatest elevations in sea level will occur far from the ice
sheets, while Greenland and West Antarctica will experience a depression of sea level!
For readers who would like to learn more about climate change and rising sea levels,
I can thoroughly recommend the topic High Tide on Main Street: Rising Sea Level and the
Coming Coastal Crisis (second edition) by John Englander, published in 2013. It is a mas-