TORONTO - Global warming could leave the the Arctic without ice during the summer as early as 2040, a study by a team of US and Canadian scientists shows.
The research, to be published by the scientific journal Geophysical Research Letters on Tuesday, found that the extent of sea ice each September could be reduced so abruptly that, within about 20 years, it may begin retreating four times faster than at any time in the observed record.
"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," said lead researcher Marika Holland from the US National Center for Atmospheric Research (NCAR).
"These changes are surprisingly rapid," Holland said in a news release on Monday.
The study indicated that if greenhouse gases continue to build up at the current rate, the Arctic's future ice cover will go through periods of relative stability, followed by abrupt retreat as the Arctic Ocean warms.
In one model simulation, the September ice shrinks from about 2.3 million square miles (6 million square km) to 770,000 square miles (2 million square km) in a 10-year period. By 2040, only a small amount of perennial sea ice would remain along the north coasts of Greenland and Canada, while most of the Arctic basin would be ice-free in September.
The winter ice also thins from about 12 feet (3.7 metres) thick to less than 3 feet (1 metre).
"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," Holland said.
The study was jointly conducted by NCAR, the University of Washington and Montreal's McGill University.
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