A NASA analysis has for the first time measured the amount of multiyear ice that is lost from the Arctic each year as a result of melting.
Multiyear ice is ice which makes it through more than one summer, making it ever more resistant to melting as the year’s progress. Or that used to be the case. Now, however, with increasing temperatures in the Arctic region the old sea ice is not lasting as long as it used to.
Ron Kwok and Glenn Cunningham at NASA’s Jet Propulsion Laboratory in Pasadena, California have analysed the amount of ice that melts compared to the amount of ice that is blown out of the Arctic by winds, known as export.
Between 1993 and 2009, 1,400 cubic kilometers (336 cubic miles) of ice was lost as a result of melt, rather than export.
“The paper shows that there is indeed melt of old ice within the Arctic basin and the melt area has been increasing over the past several years,” Kwok said. “The story is always more complicated — there is melt as well as export — but this is a another step in calculating the mass and area balance of the Arctic ice cover.”
The study was published in the October edition of the journal Geophysical Research Letters.