Cutting greenhouse gases by 70 percent this century would spare the planet the most traumatic effects of climate change, including the massive loss of Arctic sea ice, a study said on Tuesday.

Warming in the Arctic would be almost halved, helping preserve fisheries, as well as sea birds and Arctic mammals like polar bears in some regions, according to scientists at the National Center for Atmospheric Research (NCAR).

But the massive cuts of greenhouse gas emissions advocated by the researchers would only "stabilize the threat of climate change and avoid catastrophe," said NCAR scientist Warren Washington, the study's lead author.

The cuts would also prevent huge losses of permafrost and a significant rise in the sea level, said the study.

"This research indicates that we can no longer avoid significant warming during this century," said Washington, who ran a series of global supercomputer studies.

The planet's average temperatures have warmed by nearly one degree Celsius since the pre-industrial era. Most of the warming is due to emissions from greenhouse gases, chief among them carbon dioxide, the study noted.

Those gases have increased from a pre-industrial level of about 284 parts per million (ppm) in the atmosphere to more than 380 ppm today. Recent studies have found that temperatures would reach the threshold for dangerous climate change if they rise by an additional one degree Celsius.

If carbon dioxide emissions were to plateau and maintained at 450 ppm, global temperatures would rise by 0.6 degrees Celsius by the end of the century, the study said.

But if emissions were allowed to continue their current trend, temperatures would rise by almost four times that amount, to 2.2 degrees Celsius.

Holding emissions at 450 ppm would translate to sea levels rising by 14 centimeters instead of 22 centimeters due to thermal expansion. Arctic ice volume would shrink by almost a quarter in summertime and stabilize by 2100.

"This study provides some hope that we can avoid the worst impacts of climate change if society can cut emissions substantially," Washington said.

(China Daily via AFP April 16, 2009)