NASA MODIS: Temperature Feedback magnifying climate warming in Arctic

Mosaic of images of the Arctic by MODIS. Credit: NASA

A team of researchers with the Max Planck Institute in Germany, has found that temperature feedback in the Arctic is causing more warming in that region than sea ice albedo feedback.

In their paper published in the journal Nature Geoscience, the team describes how plugging data into a computer simulation revealed a "layered cake" atmosphere that traps heat over the polar cap.

Scientists have known for several years that temperatures in the Arctic are rising faster (due to global warming) than for the rest of the planet—for the most part, most climatologists have attributed this to sea ice albedo—a feedback system where a small rise in temperature leads to melting of ice and snow.

Less ice and snow means less heat is reflected back into space, which means more warming occurs, and so on. In this new effort, the researchers suggest that while sea ice albedo is causing temperatures to rise, it's second to temperature feedback in overall impact.

To gain a better perspective on why Arctic temperatures are increasing so much, the researchers turned to highly sophisticated and data intensive climate computer models.

Their model showed a cap of cold layered air hovering over the Arctic, holding in the heat. The researchers believe their simulation accurately portrays what actually exists in the real Arctic.

Normally, they explain, changing weather patterns (such as thunderstorms) in other parts of the world keep atmospheric air churning, which in turn allows heat closer to the ground to be moved higher, allowing some of it to escape into space.

Things are very different in the Arctic—there is very little churning, which means that warm air close to ground (just one to two kilometers thick) remains where it is, trapped by a heavy layered atmosphere.

The simulation also helps to explain why Arctic warming is more pronounced in the winter than during other seasons—even less mixing of the air in the atmosphere occurs because the air is so cold.

The team reports that their simulations show that the temperature feedback that occurs in the Arctic is causing more average temperature increase than sea ice albedo, the second most critical factor in causing warming.

They have not used their findings to try to predict what sort of overall impact increasing Arctic temperatures might have on the rest of the planet, however, if the polar cap will melt completely, or if it does, when it might occur.

More information: Arctic amplification dominated by temperature feedbacks in contemporary climate models, Nature Geoscience (2014) DOI: 10.1038/ngeo2071

Antarctic: Ice Sheet warming Faster

The West Antarctic Ice Sheet, whose melt may be responsible for 10 percent of the sea-level rise caused by climate change, is warming twice as quickly as previously thought, a recent study shows.

A re-analysis of temperature records from 1958 to 2010 revealed an increase of 2.4 degrees Celsius (36.3 degrees Fahrenheit) over the period -- three times the average global rise.

The increase was nearly double what previous research had suggested, and meant this was one of the fastest-warming regions on Earth, according to paper co-author David Bromwich of the Byrd Polar Research Center.

"Our record suggests that continued summer warming in West Antarctica could upset the surface balance of the ice sheet, so that the region could make an even bigger contribution to sea-level rise than it already does," he said.

Scientists believe the shrinking of the West Antarctic Ice Sheet is responsible for about 10 percent of global warming-related sea-level rise, which if unchecked threatens to flood many coastal cities within a few generations.

The sheet, a huge mass of ice up to four kilometres (2.5 miles) thick that covers the land surface and stretches into the sea, is melting faster than any other part of Antarctica.

NASA study: California Lakes warming quicker than expected

New U.S. scientific findings suggest that climate change may be affecting aquatic environments faster and sooner than the atmosphere.

Researchers from NASA's Jet Propulsion Laboratory in Pasadena, Calif., came to conclusions after noticing that Lake Tahoe, Clear Lake and four other big lakes in Northern California and Nevada are heating up faster than the surrounding atmosphere, The Sacramento Bee reported Sunday.

The newspaper said the researchers tapped satellite sensor temperature data compiled over 18 years in what is believed to be the first time that long-range lake surface temperatures have been dissected. What the data reportedly showed is that the lakes' water temperature rose two times faster, on average, than the regional air temperatures.

"It was a big surprise to see that," Philipp Schneider, the study's lead author and a post-doctoral research scientist at the NASA lab, told the Bee. "If it turns out they're actually changing faster than the air temperature, then there's a whole new phenomenon going on here.

The lake ecosystems are going to be very much affected, especially because the trend we observed seems to be quite rapid."