From: Andy Soos, ENN
Published February 26, 2013 08:12 AM

Polar Snow Up

More snow in the Arctic is good. Less snow elsewhere may be a problem. A new cli­mate model pre­dicts an increase in snow­fall for the Earth’s polar regions and high­est alti­tudes, but an over­all drop in snow­fall for the globe, as car­bon diox­ide lev­els rise over the next century. The decline in snow­fall could spell trou­ble for regions such as the west­ern United States that rely on snow melt as a source of fresh water.

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The pro­jec­tions are the result of a new cli­mate model devel­oped at the National Oceanic and Atmos­pheric Admin­is­tra­tion (NOAA) Geo­phys­i­cal Fluid Dynam­ics Lab­o­ra­tory (GFDL) and ana­lyzed by sci­en­tists at GFDL and Prince­ton Uni­ver­sity. The study was pub­lished in the Jour­nal of Climate.

The model indi­cates that the major­ity of the planet would expe­ri­ence less snow­fall as a result of warm­ing due to a dou­bling of atmos­pheric car­bon diox­ide. Obser­va­tions show that atmos­pheric car­bon diox­ide has already increased by 40 per­cent from val­ues in the mid-19th cen­tury, and, given pro­jected trends, could exceed twice those val­ues later this cen­tury. In North Amer­ica, the great­est reduc­tions in snow­fall will occur along the north­east coast, in the moun­tain­ous west, and in the Pacific North­west. Coastal regions from Vir­ginia to Maine, as well as coastal Ore­gon and Wash­ing­ton, will get less than half the amount of snow cur­rently received.

In very cold regions of the globe, how­ever, snow­fall will rise because as air warms it can hold more mois­ture, lead­ing to increased pre­cip­i­ta­tion in the form of snow. The researchers found that regions in and around the Arc­tic and Antarc­tica will get more snow than they now receive.

The high­est moun­tain peaks in the north­west­ern Himalayas, the Andes and the Yukon region will also receive greater amounts of snow­fall after car­bon diox­ide dou­bles. This find­ing clashes with other mod­els which pre­dicted declines in snow­fall for these high-altitude regions. How­ever, the new model’s pre­dic­tion is con­sis­tent with cur­rent snow­fall obser­va­tions in these regions.

The model is an improve­ment over pre­vi­ous mod­els in that it uti­lizes greater detail about the world’s topog­ra­phy — the moun­tains, val­leys and other fea­tures. This new high-resolution model is anal­o­gous to hav­ing a high-definition model of the planet’s cli­mate instead of a blurred picture.

Snow, once on the ground, affects the local environment.  After attaching itself to hillsides, blown snow can evolve into a snow slab—an avalanche hazard on steep slopes. The existence of a snowpack keeps temperatures lower than they would be otherwise, as the whiteness of the snow reflects most sunlight, and any absorbed heat goes into melting the snow rather than increasing its temperature. The water equivalent of snowfall is measured to monitor how much liquid is available to flood rivers from melt water that will occur during the following spring. Snow cover can protect crops from extreme cold. If snowfall stays on the ground for a series of years uninterrupted, the snow pack develops into a mass of ice called glacier. 

So less snow means less snow melt and less water for some regions at times when they historically expect water.  More snow in the polar north means the land will be colder and stay more frozen over time.  As one can see predicting the effects of climate change is quite tricky.

For further information see Snow.

Polar North image via Wikipedia.

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