What we are seeing, here and now, is the transformation of the atmospheric physics of this planet.
This great dissolution, of ice and certainties, is happening so much faster than most climate scientists predicted...
The melting disperses another belief: that the temperate parts of the world – where most of the rich nations are located – will be hit last and least, while the poorer nations will be hit first and worst. New knowledge of the way in which the destruction of the Arctic sea ice affects northern Europe and North America suggests that this is no longer true. A paper published earlier this year in Geophysical Research Letters shows that Arctic warming is likely to be responsible for the extremes now hammering the once-temperate nations.
The north polar jet stream is an air current several hundred kilometres wide, travelling eastwards around the hemisphere. It functions as a barrier, separating the cold, wet weather to the north from the warmer, drier weather to the south. Many of the variations in our weather are caused by great travelling meanders – or Rossby waves – in the jet stream.
Arctic heating, the paper shows, both slows the Rossby waves and makes them steeper and wider. Instead of moving on rapidly, the weather gets stuck. Regions to the south of the stalled meander wait for weeks or months for rain; regions to the north (or underneath it) wait for weeks or months for a break from the rain. Instead of a benign succession of sunshine and showers, we get droughts or floods.
The warming of the Arctic appears to be changing the trajectory of the jet stream in certain seasons, leading to more persistent weather patterns. The solid line represents a typical jet stream trajectory, and the dashed line represents the expected northward elongation of the waves in the jet stream in response to Arctic warming. Image and description from Linking Weird Weather to Rapid Warming of the Arctic
The Florida Panhandle/Alabama flooding and the recent rash of tornadoes were caused by a Rossby wave blocking pattern. Connect the dots, folks, from Arctic melt to Florida flood.
To get five times the typical monthly rainfall in roughly 24 hours is mind-boggling.
The overall storm system was monstrous. A strongly pronounced kink in the jet stream has been effectively stuck in place for days, held fast by a sluggish dome of high pressure over Hudson Bay in Canada. As I wrote earlier this week, blocking patterns like this are known for their ability to create extreme weather.
This is the same weather pattern responsible for a rash of tornadoes since Sunday and heavy snow in the Dakotas. [emphasis mine]
New evidence of Rossby Waves creating extreme weather.
The study showed that larger waves can lead to droughts in central North America, Europe and central Asia, and western Asia exposed to prolonged wet spells. It also shows western North America and central Asia are more prone to heat waves, while eastern North America is more likely to experience prolonged outbreaks of cold.
... the weather extremes they examined were month-long heat waves, cold spells, droughts and prolonged wet periods, which occurred over large areas.
... "The study revealed that these types of events are strongly related to well-developed wave patterns, and that these patterns increase the chance of heat waves in western North America and central Asia, cold outbreaks in eastern North America, droughts in central North America, Europe and central Asia, and wet spells in western Asia. [emphasis mine]
This set of images nicely illustrates how a deeply curved jet stream can simultaneously bring 90°F weather to northern Canada and cold air to Minnesota.