Global Science Report is a weekly feature from the Center for the Study of Science, where we highlight one or two important new items in the scientific literature or the popular media. For broader and more technical perspectives, consult our monthly “Current Wisdom.”
I recently returned from a trip to Greenland’s Jokabshavn Glacier, which discharges more ice than any other in the Northern Hemisphere.
Our route of flight from Reykjavik traversed the ice cap from about fifty miles north of Angmassalik to the airport at Ilulissat, on Disko Bay, about one-third of the way up Greenland’s west coast. In southeastern Greenland, we flew very close to the country’s second-highest peak, Mt. Forel (11,099 feet), and in the near future I will upload a image of a nearby mountain approximately 8,000 feet high completely covered by the ice cap.
It is obvious from the air that there is very little movement over the deepest regions of the ice, and the drift patterns in the lee of some of the submerged peaks are strongly suggestive of at least some regional accumulation. There is virtually no evidence for summer melt in the southeast, while the southwest portion of the ice cap is known to melt and refreeze at the surface on an annual cycle—I saw considerable evidence for multi-year, but small, lakes in that region.
In preparation, I read just about everything I could get my hands on, including a recent very remarkable paper by Dorthe Dahl-Jenson and about 70 coauthors. Dahl-Jensen heads up the Center for Ice and Climate at the University of Copenhagen. Dahl-Jenson’s team drilled to the bottom of the ice in northwestern Greenland, providing us with the first climate history of Greenland that includes the warmest period in the last interglacial period, from about 128,000 to 122,000 years ago, known as the Eemian. That was embedded in the Sangamon Interglacial, which ran from approximately 135,000 to 95,000 years ago.
(For perspective, the last (Wisconsin) glaciation started then and lasted to (nominally) 10,800 years ago—that last date being about a blink of a geologist’s eye ago. Homo sapiens appeared in the ice age, and evidence is that proto-civilization developed while the hemisphere was glaciated.)