It appears that this month will achieve snow extent among the top two Februaries on record.

As you can see in the Rutgers University maps below for mid-February, the excess snow cover is necessarily found at lower latitudes.  Snow cover radiates out from the pole, so the only place where snow extent can increase is towards the south.

The implication of the observed trend towards increasing snow extent is that the Northern Hemisphere autumn/winter snow line is moving southwards over the last ten to twenty years.

Daily Departure – February 13, 2010 (Day 44)

Source : Rutgers University Global Climate Lab

Daily Snow – February 13, 2010 (Day 44)

Source : Rutgers University Global Climate Lab

We see southern snow cover this year in places like Greece, Northern China, and Alabama that are not normally covered with snow in mid-February.  The map below shows the “normal” snow extent measured since 1966.

Daily Climatology – February 13 (Day 44)

Source : Rutgers University Global Climate Lab

Some people have been claiming that the anomalous snow this winter is due to warming temperatures.   The New York Times reports on the record snow :

Most climate scientists respond that the ferocious storms are consistent with forecasts that a heating planet will produce more frequent and more intense weather events.

It doesn’t make a lot of sense that warming temperatures would cause the snow line to move south.  Lower latitudes normally receive rain rather than snow, because the air is already too warm for snow.  Further warming would be expected to move the snow line north – not south – and that is exactly what the climate models predict.  Indeed, Time Magazine claims that this has already happened: “large-scale cold-weather storm systems have gradually tracked to the north in the U.S. over the past 50 years.”

As far as snow depth goes, Washington D.C. recently broke their 1899 snow record of 54.4 inches and now has a new record of 54.9 inches.  We are told that the new record is due to “extreme weather” caused by “global warming.”  If so, what caused the nearly identical “extreme weather” over a century ago?  Alarmists tell us that heavy snow used to be caused by cold, but now is caused by warmth.  The 1899 record was set long before the hockey stick brought temperatures to “unprecedented levels.”

Now lets take their poor logic one step further.  Ice ages occur when the snow line moves very far south.  If “most climate scientists” are claiming that global warming is causing the snow line to move south, then the logical corollary is that ice ages are caused by further warming temperatures.  Clearly that is not true.

Wikipedia map of the last ice age

Furthermore, Hansen correctly tells us that as the snow line moves south, the earth’s albedo increases causing further cooling.

The sensible theory is that the snow line moves south when the climate is cold, and north when the climate is warm.  And the record snow we are seeing this winter is due to cold, not warm temperatures.

Today’s NBA All-Star game in Dallas is covered with snow.  Last time I checked, Texas was in the South.

Feb. 15, 2010