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Global climate change

Northern Hemispheric Snow Cover Trends

2/19/2013, 10:40:48 AM

Has there been a noticeable decrease in snow cover across the northern Hemisphere since the mid 1960's?

Well, it depends on the time of the year.

My friends from the Rutgers University Global Snow Lab (my alma mata 89') keep a close track of global snow cover and have data that go back to the 1960's.

For the month of January, there has actually been an upward trend in snow cover over the past dozen years. Part of the reason for this is that the significant warming in the high latitudes over the past 20 years has caused an increase in moisture (warmer air holds more moisture than cold) and thus more snowfall over areas that are normally quite dry during the winter.


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However, it is a different story when you look at the month of June below....


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There has been a fairly sharp decrease in snow cover anomalies across the northern hemisphere for June. Obviously, snow cover is normally confined to the far north and very high elevations during this time of year, but this also makes sense with the amount of warming and the reduction of sea ice that we have seen in this part of the globe over that past 20-30 years. Temperatures in June are just getting too warm to support snow cover in some areas that were normally still covered with snow over the past 40 years.

When we look at all the months going back to 1966 we can see that snow cover has been averaging below normal since the mid-1980's, but that the trend since the mid-1980's has been quite stable. The longer term trend since 1966 appears to be slightly downward though.


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All images courtesy of the Rutgers University Global Snow Lab

The views expressed are those of the author and not necessarily those of AccuWeather, Inc. or AccuWeather.com

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Global climate change