Long-term trends are clear
By Bob Berwyn
SUMMIT COUNTY — Using their normal cherry picking techniques, global warming deniers have used isolated weather events like last winter’s heavy snowfalls to try and cast doubt on long-term climate predictions.
Some of the graphs that have been floating around on fringe websites like Real Science include this one from the Rutgers University Global Snow Lab. At first glance, it seems pretty convincing — The extent of snow cover during the North American winter increased slightly between 1967 and 2011, from about 16.9 million square kilometers to about 17.2 million square kilometers.
But take a look at the following graph, showing a much steeper decline in the spring snowpack — close to what’s predicted by many climate models.
So maybe that increasing winter snow cover is on the Eurasian landmass …
No increase there … and, in fact, an even steeper decline in the spring snow cover extent, from about 18.5 million square kilometers down to just barely more than 16 million square kilometers in 2011.
And finally, this graph makes it fairly clear what the long-term trend in the annual mean northern hemisphere snow cover is.