Thursday 19 October 2017

Siberian blast from the past

A man takes a dip in a river in northeast China
A man takes a dip in a river in northeast China

Michael McCarthy

YOU might think the current weather conditions are almost Siberian -- and you'd be right.

The most prolonged spell of freezing weather since 1981 is being caused by a huge mass of intensely cold air over north-east Russia, with easterly winds sweeping its glacial temperatures across northern Europe to the UK.

And just as in the 20th century's coldest-ever winter in Britain, of 1962-63 -- although not on such a severe scale -- the cold is being held in place by what is known as a 'blocking anti-cyclone', a static area of high pressure over Greenland which is preventing the usual warmer, damper westerly winds from reaching us across the Atlantic.

The present situation is known as an 'Omega block' as it consists of two high pressure systems which on a weather map resemble the two arms of the Greek letter Omega -- the Greenland one, and the Siberian anti-cyclone itself (whose stillness and clear skies are causing its intense cold, as much as 48C below zero in some places).

So if it is the longest cold snap for 29 years, does that prove that the idea of global warming is a non-starter? It does not.

Looking at north-east America and Canada, in North Africa, across the Mediterranean, through to south-west Asia, temperatures are very much above normal -- in many places by more than 5C, and in parts of northern Canada, by more than 10C.

And closer to home, in Madrid the temperature was 10C against a seasonal average of 9C, while in Rome it was 13C, compared to a seasonal average of 11C.

The weather's natural variability means it is impossible to draw long-term conclusions about a changing climate from any single episode, be it of hot, or cold. (© Independent News Services)

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