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Arctic sea ice is retreating at such a rapid rate that north pole summers could be ice-free by 2040.

New research published in Tuesday's edition of Geophysical Research Letters indicates that the next few decades could produce dramatic changes that will drastically change the ecology of the far north.

The study was conducted by a team of scientists at the U.S. National Centre for Atmospheric Research, the University of Washington and McGill University, and funded by the National Science Foundation and NASA.

The researchers analyzed the impact of greenhouse gas emissions on the Arctic, then ran scenarios through powerful computers that show the extent of sea ice each September. In those scenarios, the rate of sea ice reduction is so rapid that it could be retreating four times faster than any observed record within about 20 years.

“We have already witnessed major losses in sea ice, but our research suggests that the decrease over the next few decades could be far more dramatic than anything that has happened so far,” NCAR scientist Marika Holland, the study's lead author, said in a release.

“These changes are surprisingly rapid.”

The team first simulated fluctuations in ice cover since 1870, including the significant shrinkage recorded since 1979.

They then simulated future ice loss, and found the Arctic was heading towards a critical point where the reduction in sea ice would create conditions that would further hasten the reduction of sea ice.

In essence, says Dr. Holland, a positive feedback loop would spell the end of summer ice caps.

“As the ice retreats, the ocean transports more heat to the Arctic and the open water absorbs more sunlight, further accelerating the rate of warming and leading to the loss of more ice,” Dr. Holland said.

That would have dramatic implications for the entire Arctic region, she said.

The model results indicate that, if greenhouse gases continue to build up in the atmosphere at the current rate, the Arctic's future ice cover will go through periods of relative stability before experiencing an abrupt retreat.

In one model simulation, the September ice shrinks so much that, by 2040, only a small amount of perennial sea ice remains along the north coasts of Canada and Greenland, with most of the Arctic basin ice-free. The winter ice in that prediction also thins from about 12 feet thick to less than 3 feet.

The research team points to several reasons for the abrupt loss of ice in a gradually warming world. Open water absorbs more sunlight than does ice, meaning that the growing regions of ice-free water will accelerate the warming trend. In addition, global climate change is expected to influence ocean circulations and drive warmer ocean currents into the Arctic.

Reducing the amount of greenhouse gas in the environment could slow that process, Dr. Holland said. While summer ice would still retreat, she said the rate would be much slower.