(CNN) -- The North Pole may be briefly ice-free by September as global warming melts away Arctic sea ice, according to scientists from the National Snow and Ice Data Center in Boulder, Colorado.
"We kind of have an informal betting pool going around in our center and that betting pool is 'does the North Pole melt out this summer?' and it may well," said the center's senior research scientist Mark Serreze.
It's a 50-50 bet that the thin Arctic sea ice, which was frozen last autumn, will completely melt away at the geographic North Pole, Serreze said.
The ice retreated to a record level in September when the Northwest Passage -- the sea route through the Arctic Ocean -- opened up briefly for the first time in recorded history.
"What we've seen through the past few decades is the Arctic sea ice cover is becoming thinner and thinner as the system warms up," Serreze said.
Specific weather patterns will determine whether the North Pole's ice cover melts completely this summer, he said.
