Global warming to melt Arctic sea ice away by 2040

Stan Beer
Wednesday, 13 December 2006 03:11

Science - Climate

A new scientific research report predicts that the frozen sea areas in the Arctic circle will be completely gone by the summer 2040 due to the impact of global warming resulting from greenhouse gas emmissions.

According to the study, by a team of scientists from the National Center for Atmospheric Research (NCAR), the University of Washington, and McGill University, scenarios run on supercomputers show that sea ice 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.

The increasing rate of melting sea ice is contributing to a positive feedback system, which feeds global warming further because open ocean absorbs heat from the sun rather than reflects back into space as does ice.

"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," says NCAR scientist Marika Holland, the study's lead author. "This is a positive feedback loop with dramatic implications for the entire Arctic region.

"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,"  "These changes are surprisingly rapid."

The team of researchers studied a series of seven simulations run on the NCAR-based Community Climate System Model for studying climate change. The scientists first tested the model by simulating fluctuations in ice cover since 1870, including a significant shrinkage of late-summer ice from 1979 to 2005. The simulations closely matched observations, a sign that the model was accurately capturing the present-day climate variability in the Arctic.

The team then simulated future ice loss. 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 followed by abrupt retreat. For example, in one model simulation, the September ice shrinks from about 2.3 million to 770,000 square miles in a 10-year period. By 2040, only a small amount of perennial sea ice remains along the north coasts of Greenland and Canada, while most of the Arctic basin is ice-free in September. The winter ice also thins from about 12 feet thick to less than 3 feet.

There is some positive news in the report however. According to the study, mankind can still affect and slow down the melting trend.

The scientists also conclude by examining 15 additional leading climate models, that if emissions of carbon dioxide and other greenhouse gases were to slow, the likelihood of rapid ice loss would decrease. Instead, summer sea ice would probably undergo a much slower retreat.

"Our research indicates that society can still minimize the impacts on Arctic ice," Holland said.