Study: Arctic climate at tipping point?

BOULDER, Colo., June 30 (UPI) -- Climate systems in the arctic may be more affected by global warming than previously thought and may be nearing a climate-change tipping point, a study says.

Although the arctic region has gone through periods in the past when it was warmer than it is today, levels of atmospheric carbon dioxide were only slightly higher than current figures, a University of Colorado at Boulder study released Wednesday says.

Current global warming from greenhouse gases generated by human activities could warm the arctic to levels above the melting point of ice, the study said.

Arctic temperatures have risen by about 1.8 degrees F in the past 20 years in response to greenhouse warming, a trend expected to continue in the coming centuries, the international study led by UC reported.

"As temperatures approach 0 degrees Celsius, it becomes exceedingly difficult to maintain permanent sea and glacial ice in the arctic," the study said. "Thus current levels of CO2 in the atmosphere of approximately 390 parts per million may be approaching a tipping point for irreversible ice-free conditions in the arctic."