NOVOSIBIRSK, April 5. /TASS/. An international group of researchers, some of them working for Novosibirsk State University and for the Institute of Oil and Gas Geology and Geophysics that reports to the Russian Academy of Sciences, claims it has tracked down the main cause behind the melting of the Greenlandic ice sheet, the press service of the university told TASS on Tuesday.
"The researchers link the thinning of the mass of the ice sheet, which is taking place today, to the events of the period some 80 million to 35 million years ago - Greenland’s passage over an ancient mantle plume," a spokesperson for the press service said.
A plume in this context stands for a hot mantle flow capable of piercing the earth’s crust and breaking outside with the resultant formation of a volcano.
The scientists arrived at the idea upon tapping meltwater under the masses of Greenlandic ice. While previously the theory suggested that glaciers were melting only in the coastal areas of the huge island, the drilling done in 2001 exposed a seam of meltwater between rock and ice. As the thickness of the ice sheet reaches 3,000 meters at the site and air temperatures never rise above zero degrees Celsius, there should be no meltwater there, since the latter is typically produced by subglacial rivers and lakes.
Scientists drew a conclusion that the melting has been produced by a plume, which is now passing under Island and has the name of ‘Islandic’. Geologists know it perfectly well.
It turns out now that Greenland really passed over it millions of years ago. Computations of the heat flow the plume might have generated show it can be sufficient for melting the lower section of the ice sheet.
"The research has shown the Islandic plume left an imprint on Greenland’s lithosphere," the press service quoted Dr. Ivan Kulakov, the director of laboratories at Novosibirsk University and the Institute of Oil and Gas Geophysics. "Thus the echoes of events that took place millions of years ago can affect the diminishing the mass of Greenlandic glaciers along with the fast changes of climate on the earth."
Results of the research have already been published by the Nature Geoscience magazine.
The melting of Greenlandic glaciers poses one of the most serious climatic challenges nowadays. The masses of ice concentrated on the island are so huge that their full melting could raise the level of the world ocean by about 7 meters and thus produce a colossal flooding.
The melting and movement of glaciers result in a situation where Greenland’s loss of ice has outstripped the ability to accumulate ice by a big margin.