The seasonal cooling effect of light-reflecting snow and ice in the Northern Hemisphere may be weakening at twice the rate predicted by climate models, a new study shows, accelerating the impact of global warming.
A long-term retreat in snow and ice cover in the Northern Hemisphere is weakening the ability of these seasonal cloaks of white to reflect sunlight back into space and cool global climate, according to a study published this week.
Indeed, over the past 30 years, the cooling effect from this so-called cryosphere – essentially areas covered by snow and ice at least part of the year – appears to have weakened at more than twice the pace projected by global climate models, the research team conducting the work estimates.
The study, which appeared online Sunday in the journal Nature Geoscience, represents a first cut at trying to calculate from direct measurements the impact of climate change on the Northern Hemisphere's cryosphere. The study was conducted by a team of federal and university scientists who examined data gathered between 1979 and 2008.
Of particular interest is a self-reinforcing process, or feedback, though which warming reduces snow and ice cover. Those reductions expose more ocean and landscape to sunlight during spring, summer and fall. After absorbing the sunlight, these exposed features radiate the heat back into the atmosphere. This accelerates the loss of snow and ice already triggered by global warming.
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