Welcome to the new weather normal

Canadians in Central and Atlantic Canada can be forgiven for feelings of bitter irony at the vicious cold. Eastern Canada is not feeling the warmth of global warming, despite the fact that last year was the warmest on record according to NASA’s Goddard Institute for Space Studies.

Nor are they consoled by the record-high temperatures in the west. To their chagrin, spring-like conditions are sprouting early blossoms in the lower mainland and creating record highs all over B.C.

The weather looks like a repeat of last year and it could well be the new normal. The jet stream, which divides warm and cold air, is stalled again. The pattern that brought the “polar vortex” to north-eastern North America in the winter of 2013/14 is bringing the “Siberian Express” this year. jetstream

Call it what you will, it’s deadly. Wind chills of -35 in Toronto claimed the life of a three-year-old Elijah Marsh after he wandering out of an apartment building in the middle of the night. At least 23 people died in the U.S. in the second week of February alone.

That demarcation line is a river of wind that flies across North America from west to east at speeds of approximately 100 kph and altitudes of 10 kilometres.

I think of the jet stream as a flag in the wind. Viewed from the top, the flag has curvy oscillations. When the wind is strong, the flag blows almost straight back. In a mild wind, the flag gently waves back and forth.

When the jet stream is strong, it blows straight across the continent, whipping back and forth. Those oscillations bring variations in weather. When the jet stream blows slowly, the waves are larger and slower. So slowly, in fact, that the pattern gets stuck in its current configuration for months.

The jet stream is blowing slower than usual because Arctic Canada is warming more quickly than the rest of the continent. Temperature difference is what drives the wind. In the past, when the temperature difference was great, the jet stream was less likely to get stuck in any pattern as it raced along a path parallel with the U.S. – Canada border.

Of course, things are not quite as simple as I outlined. The El Nino pushes the jet stream south and La Nina, north. Nor is North America the only continent affected.

Climate change can have catastrophic effects on geopolitics as in 2010 when the jet stream got stuck over Russia and a massive high caused a drought. Jeff Masters says: “The drought and heat wave was Russia’s deadliest and most expensive natural disaster,” in Scientific American.

The drought drove up grain prices and fomented unrest in the Arab world as Russia cut off exports, precipitating the “Arab Spring” that toppled governments.

Closer to home, floods and drought are affecting the U.S. as the jet stream slows. “Some of the most iconic and destructive weather events in U.S. history – the ‘supertornado’ outbreak of 1974, the Dust Bowl heat and drought of 1936, and the great Mississippi River flood of 1927 – were all matched in 2011 and 2012 alone,” warns Masters.



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