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Melting Arctic, Mangled Jet Stream and Massive Forest Fires
Jet streams consists of bands of very strong winds which move weather systems around the globe. These have been relatively stable until recently due to a decrease in temperature gradient between the equator and north pole. Below is a satellite image of a mangled jet stream, using Earth Nullschool, creating blocking patterns that makes weather system seem “stuck”. For example, here in southeast Sweden we are experiencing record warm May temperatures (20-25 C), little rain or wind with a high risk of forest fires.
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| Jet stream pattern over Europe, with warm air “stuck” over Scandinavia |
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A similar situation but much worse is occurring in Canada where massive forest fires have driven 88,000 canadians out of their homes in Fort McMurray. These people are now climate refugees and more damage is yet to come as the fire is now moving towards Alberta’s tar sand fields and could double in size due to strong winds and dry conditions. The fire cover an area as large as Hong Kong.
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Melting Arctic sea ice causes more heat to be absorbed by the darker surface of the ocean, especially in late spring when the sun is really strong. The extra heat is then also transferred into the atmosphere. When this happens the lower layers of the atmosphere warms and expand, pushing up the higher layers and causing the jet stream to bulge. As the sea ice disappears and the atmosphere in the Arctic warms the airflow in the jet stream is more likely to loop and bulge, causing blocking events.
“High pressure systems over Greenland can have the effect of blocking polar jet stream flow over part of the North Atlantic […] causing the jet stream to split into branches and bringing about all kinds of severe weather events as a result.” according to Dr. Edward Hanna from the University of Sheffield.
Researchers are worried that these type of blocking events of high pressure systems over Greenland can lead to rapid melt of the ice sheet as well as causing extreme weather events over the northern hemisphere.
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