Shrinking snow and ice cover ‘making global warming worse’

January 19th, 2011 - 4:28 pm ICT by ANI  

London, Jan 19 (ANI): A new research from the University of Michigan has shown that the decreasing snow and ice cover on Earth’s surface has contributed much more to global warming than models predict they should have.

Snow and ice reflect the sun’s light and heat back to space, causing an atmospheric cooling effect. But as the planet warms, more ice melts and in some cases, less snow falls, exposing additional ground and water that absorb more heat, amplifying the effects of warmer temperatures.

“Our analysis of snow and sea ice changes over the last 30 years indicates that this cryospheric feedback is almost twice as strong as what models have simulated,” said Mark Flanner, assistant professor in the Department of Atmospheric, Oceanic and Space Sciences.

“The implication is that Earth’s climate may be more sensitive to increases in atmospheric carbon dioxide and other perturbations than models predict,” he added.

The cryosphere is the planet’s layer of snow, sea ice and permanent ice sheets.

The team found that for every 1 degree Celsius rise in the Northern Hemisphere, an average of 0.6 fewer watts of solar radiation reflected to space per square meter because of reduced snow and sea ice cover.

Flanner points out that the models typically calculate this feedback over 100 years, which lends inconsistency to the data.

“The cryospheric albedo feedback is a relatively small player globally, but it’s been a surprisingly strong feedback mechanism over the past 30 years,” Flanner said.

“A feedback of this magnitude would translate into roughly 15 percent more warming, given current understanding of other feedback mechanisms.”

To counteract this effect, the scientific consensus is that the global average temperature should stay within 2 degrees Celsius, or 3.6 degrees Fahrenheit, of pre-industrial levels.

“People sometimes criticize models for being too sensitive to climate perturbations,” Flanner said.

“With respect to cryospheric changes, however, observations suggest the models are a bit sluggish.”

The research is published online in Nature Geoscience. (ANI)

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