Washington, D.C. ? There’s a 50-50 chance that the North Pole will be ice-free this summer, which would be a first in recorded history, a leading ice scientist says.

The weather and ocean conditions in the next couple of weeks will determine how much of the sea ice will melt, and early signs are not good, said Mark Serreze. He’s a senior researcher at the National Snow and Ice Data Center and the University of Colorado in Boulder, Colo.

The chances for a total meltdown at the pole are higher than ever because the layer of ice coating the sea is thinner than ever, he said.

“A large area at the North Pole and surrounding the North Pole is first-year ice,” Serreze said. “That’s the stuff that tends to melt out in the summer because it’s thin.”