Removing the weather wrapping from climate change

Canadians have watched our TV weather reporters with their moving images of fronts, lines of pressure and varying coloured charts that made daily weather changes very visible. We listened why the balmy temperatures we were experiencing would change to frigid within twenty four hours. We gathered that the cause of this change was an invasion of cold air from the Arctic.

Canadians have understood that there are winter warming periods, such as the almost traditional February thaw. The mild periods have been the exception and not the rule, so we never questioned how they came about.  For most parts of Canada the winter of 2012 is different: so far it has been a series of mild periods interrupted by spells of cold weather.

Canadian media have been covering the story of Canada’s crazy winter of 2012. We were somewhat mystified by the title of a good Canadian Press article that read:

“Research suggests warmer summers could be causing colder winters”

What’s that again?

Why wouldn’t warmer summers be followed by warmer winters?  That has been our experience with the winter of 2011-2012. Global warming should at least give us some relief from snow and ice and the shovelling and winter driving conditions they bring.

The article explains that our baffling winter is attributable to a phenomenon known as the Arctic Oscillation, a sort of La Nina of the high latitudes.

“When that oscillation is strong, it creates powerful east-west winds that block cold polar air from drifting south. But when the oscillation is weak, more of that air starts moving north-south, pulling the Siberian High [extreme cold weather] downwards.”

If curiosity pushes you to find out more, go to the CTV News story. There you will find references that connect the Arctic Oscillation to the snowfall over Siberia.  The Siberian snowfall is connected to the warm Arctic summers.  And in turn it contributes to the strength of the Arctic Oscillation that keeps that nasty cold weather in the Polar Regions, where it belongs.

The article concludes with the encouraging (?) statement:

“. . . the pattern of warm springs, summers and falls followed by cold winters is likely to persist — at least until climate change advances to the point where November precipitation in Siberia falls as rain, not snow.”

We will revert to this topic in the near future, but not before the arrival of spring. We don’t want to tempt Old Man Winter to get revenge over the next two months for our dismissal of his sovereignty.



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