Scientists have identified a mechanism that could turn out to be a big contributor to warming in the Arctic region and melting sea ice. The research was led by scientists from the US Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab). They studied a long-wavelength region of the electromagnetic spectrum called far infrared. It's invisible to our eyes but accounts for about half the energy emitted by Earth's surface. This process balances out incoming solar energy.

Despite its importance in the planet's energy budget, it's difficult to measure a surface's effectiveness in emitting far-infrared energy. In addition, its influence on the planet's climate is not well represented in climate models. The models assume that all surfaces are 100 percent efficient in emitting far-infrared energy.

That's not the case. The scientists found that open oceans are much less efficient than sea ice when it comes to emitting in the far-infrared region of the spectrum. This means that the Arctic Ocean traps much of the energy in far-infrared radiation, a previously unknown phenomenon that is likely contributing to the warming of the polar climate.

Their research appears in the online early edition of the Proceedings of the National Academy of Sciences.

"Far-infrared surface emissivity is an unexplored topic, but it deserves more attention. Our research found that non-frozen surfaces are poor emitters compared to frozen surfaces. And this discrepancy has a much bigger impact on the polar climate than today's models indicate," says Daniel Feldman, a scientist in Berkeley Lab's Earth Sciences Division and lead author of the paper.

"Based on our findings, we recommend that more efforts be made to measure far-infrared surface emissivity. These measurements will help climate models better simulate the effects of this phenomenon on Earth's climate," Feldman says.