Really Sciency

Visit my other blog 'Really Sciency' looking at Climate Science and its portrayal, misrepresentation and denial in the media.

Friday, 2 March 2012

Snowiest four year period on record in North America ?

On Mr Goddard's blog he presented this graph and said;“This winter, global snow cover has been far above normal.

The most notable things here is that Goddard's statement may - be true but so what?, I think it needs challenged on three accounts. First; because of his myopic views that the USA, representing a few percent at most of the entire worlds surface, can in this case be used to justify anything meaningful about global warming.

Second; the apparent cherry pick of just the winter values. The amount of snow in winter is far from the only consideration. Snow extent in the spring, which may partly determine the amount of snow melt through the year is also important. That snow will feed into rivers to be used for irrigation, drinking water etc in the coming year. A more meaningful question to ask might be; How is snow and ice holding up over all?

Third; can the amount of snow actually be used as a measure against the early stages of climate change? A warmer atmosphere holds more moisture, which will eventually lead to more precipitation. If cold enough, this will actually mean more snow. A concept climate deniers refuse to get in their quest to confuse and misinform themselves and others.

In answer to the first two points a look at the other graphs from the very site Goddard got his from reveals much.

For Autumn (Fall) and Winter, there is a mix of slight increases, decreases or essentially no change in the record. Springs shows a far more dramatic decrease across all areas. Why would Goddard only pick the graph that shows the largest increase and ignore all others?

A selection of  the graphed data can be seen on an animated gif at Skeptical Science;
snow extent
Graphic from Skeptical Science

the long-term trend in spring, summer, and annual snow cover is one of rapid decline. As a result, the planet as a whole is becoming less reflective and absorbing more sunlight, which is accelerating global warming.
For point 3, I have already suggested that one of the climate changes that global warming has predicted is heavier snow falls. This isn’t just something scientists made up on the spot to try and account for recent heavier snow falls across parts of the world. It is a long standing prediction,  using models that, if you belief the ‘skeptics’, don’t work.

A quick search on 'snow and global warming' with google Scholar finds a paper;  POLAR SNOW COVER CHANGES AND GLOBAL WARMING, from way back in 1998. From the Abstract;

“Many general circulation models suggest that current precipitation amounts in polar latitudes will increase under double CO2 scenarios. Even though temperatures in such high-latitude regions should also increase under a doubling of CO2, as long as those temperatures remain below freezing, the increased precipitation should accumulate as snow.”

But very recent research also confirm this effect. Even while the world has been calculated to be loosing 150 cubic miles of ice every year, Himalayan Glaciers were found to have lost little ice because the increased melting at the lower altitudes were mostly matched by increased snow fall at higher altitudes where it was too cold to melt.

And just this week new research suggests that Arctic sea ice loss could be weakening the Jet Stream allowing colder Arctic air lower over Europe and America actually causing colder winters, including heavier snow, even while the Arctic itself is warmer than normal.

So as much as Goddard would like to claim that increased winter snow extent is evidence against global warming and cry foul when the science suggests it is actually evidence for it, it was predicted by models around a generation ago and is being confirmed by empirical evidence today.

Snowiest four year period

If you have managed to read this far and are starting to wonder what the title has to do with all this, all will now be revealed. When I challenged Goddard about his cherry picking he replied with his usual eloquence and what might just be his standard greeting to anyone actually sceptical enough to query his claims;

The last four years was the snowiest four year period on record in North America. Cut the crap, please.
Snowiest? The obvious problem here is that this is a very specific pronouncement using a very unspecific term. I asked him “How are you defining ‘snowiest’ and what data set are you using for evidence?” Clearly from the graph he supplied he was not referring to snow extent. At least ten previous years had higher records than some in the last four. He has yet to reply.

Snow is such a transient phenomena. Would he be referring to depth? It is relatively easy to measure precipitation but the depth of snow depends largely on how wet it is. Sleet, a mixture of rain and snow, will have little depth, the fluffy stuff many times more depth than the equivalent amount of water. Perhaps he was referring to the number of days it snowed? How long the snow lasted?

So there is the problem. 'Snowiest' isn’t really a scientific term that can be used in a specific claim as Goddard has done. It doesn’t mean it can’t be used as long as it is defined. In my attempts to collaborated the ‘snowiest’ years I found that NOAA do use it to refer to depth in specified cities. However I can’t find any where all these figures are collated  in a way that would indicate the depth of snow that fell over the whole area of the USA, but judging form the years that are in the top ten for the cities I’d be very surprised if the 'snowiest' added up to be 2007 through 2011.

So claiming that the 'last four years was the snowiest four year period on record in North America’ appears to be an unsubstantiated and unsubstantiable claim from Goddard.

I invite him to clarify, otherwise perhaps it is he that should cut the crap.

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