Research by Dartmouth Thayer School of Engineering graduate student Kaitlin Keegan has added critical information to a NASA annoucement today regarding melting of the Greenland Ice Sheet. "According to satellite data, an estimated 97 percent of the ice sheet surface thawed at some point in mid-July," according to the NASA release.

Keegan is an engineerig PhD student and a fellow in the Dartmouth IGERT polar enviromental change program. She studies the physical properties of the top layers of the ice, the firn, at Summit as well as NEEM, an international ice core project in Northwest Greenland. According to Keegan, the last time such a melt occured at Summit was in 1889.

"I have been focused on the melt layers present in both firn cores [Summit and NEEM] because they occur very infrequently," Kaitlin wrote on the Dartmouth IGERT blog a few days after a run of unusually warm weather created the remarkable opportunity to watch the melt occurring. "At Summit, there is only one other melt layer besides the melt layer from this past week and this previous melt layer dates to 1889."

Keegan and Mary Albert, a professor of engineering at Thayer and Executive Director of the NSF Ice Core Drilling office, are working on a paper on the topic.