Monday, December 19, 2016

Arctic ice melt 'already affecting weather patterns where you live right now'

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Damian Carrington
Monday 19 December 2016

The dramatic melting of Arctic ice is already driving extreme weather that affects hundreds of millions of people across North America, Europe and Asia, leading climate scientists have told the Guardian.

Severe “snowmageddon” winters are now strongly linked to soaring polar temperatures, say researchers, with deadly summer heatwaves and torrential floods also probably linked. The scientists now fear the Arctic meltdown has kickstarted abrupt changes in the planet’s swirling atmosphere, bringing extreme weather in heavily populated areas to the boil.

The northern ice cap has been shrinking since the 1970s, with global warming driving the loss of about three-quarters of its volume so far. But the recent heat in the Arctic has shocked scientists, with temperatures 33C above average in parts of the Russian Arctic and 20C higher in some other places.

In November, ice levels hit a record low, and we are now in “uncharted territory”, said Prof Jennifer Francis, an Arctic climate expert at Rutgers University in the US, who first became interested in the region when she sailed through it on a round-the-world trip in the 1980s.

“These rapid changes in the Arctic are affecting weather patterns where you live right now,” she said. “In the past you have had natural variations like El NiƱo, but they have never happened before in combination with this very warm Arctic, so it is a whole new ball game.

“It is inconceivable that this ridiculously warm Arctic would not have an impact on weather patterns in the middle latitudes further south, where so many people live.

“It’s safe to say [the hot Arctic] is going to have a big impact, but it’s hard to say exactly how big right now. But we are going to have a lot of very interesting weather – we’re not going to get around that one.”


the Arctic is heating up much faster than the rest of the planet.

This in turn narrows the temperature difference between the Arctic and lower latitudes, which is crucial because it is the temperature gradient between them that drives the jet stream wind, which streaks around the pole at up to 250mph and about 8km above the surface.

The jet stream forms a boundary between the cold north and the warmer south, but the lower temperature difference means the winds are now weaker. This means the jet stream meanders more, with big loops bringing warm air to the frozen north and cold air into warmer southern climes.

Furthermore, researchers say, the changes mean the loops can remain stuck over regions for weeks, rather than being blown westwards as in the past. This “blocking” effect means extreme events can unfold.


Another consequence of the fast melting Arctic raises the possibility that there may be even worse extreme weather to come, according to a few scientists: titanic Atlantic superstorms and hurricanes barreling across Europe.


“The worrying aspect is that such dynamical changes can occur more abruptly than simple background warming of the climate,” said Coumou. “Dynamical changes can change more rapidly and can therefore lead to surprises and I think there are many such possibilities in the system.”


tags: extreme weather, severe weather

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