Researchers at the Alfred Wegener Institute for Polar and Marine Research made the forecast based on a series of measurement flights over the Laptev Sea on the margins of the Arctic Ocean.
The sea is considered an "ice factory" of arctic sea ice, but at the end of last winter researchers discovered large areas of thin ice that would not withstand the upcoming summer melt, the Helmholtz Association of German Research Centers reported Wednesday.
"These results were a great surprise to us," researcher Thomas Krumpen said.
Measurement flights in March and April found areas of thin ice stretching more than 250 miles, confirming the thin ice areas were not a locally restricted phenomenon.
"A large part of the Northeast Passage was characterized by surprisingly thin ice at the end of the winter," Krumpen said.
"These huge new areas of thin ice will be the first to disappear when the ice melts in summer. And if the thin ice melts as quickly as we presume, the Laptev Sea and with it a part of the Northeast Passage will be free from ice comparatively early this summer," he said.
In the past the Laptev Sea has been navigable for a maximum of two summer months.
The Northeast Passage is viewed by shipping companies as a time- and fuel-saving alternative to the conventional Europe-Asia route, with the connection from Rotterdam, Netherlands, to Yokohama, Japan, via the Northeast Passage being some 3,800 sea miles shorter than taking the Suez Canal and Indian Ocean route.