Linking Mid-Latitude Extreme Weather Events to Arctic Amplification; Complexities Abound


Apr 16, 2021

One of the obvious consequences of abrupt climate system change is the large increase we have experienced in the frequency, severity, and duration of extreme weather events. In addition, these events are happening in regions where they did not happen before, for example, we have had large, previously unheard of snowfalls in some of the driest deserts in the world.

The top down, elevator pitch that I have used for many years is based on the fundamental physics of why the Jet Stream exists in the first place, which is due to the cold Arctic – warmer lower latitudes temperature difference creating a pressure difference driving the high altitude winds (jet streams) along with the Coriolis force effects deflecting winds to the right in the Northern Hemisphere.

As the Arctic warms at much greater rates than lower latitudes, the lower temperature gradient (thus pressure gradient) means the jet streams must slow, and thus they become much wavier in the North-South direction. Under the ridges of the Jet stream waves (Rossby Waves) there is high pressure and heat that has moved northward, while in the troughs of the waves cold dry air spills southward. If the wave locations are persistent (blocked) we can get long duration anomalously hot conditions under the ridges, and long duration storms, torrential rainfall, and flooding in the troughs.

This explains why the tremendously rapid Arctic warming is leading to increases in the frequency, severity, and duration of extreme weather events, from a top-down viewpoint.

Bottom-up is more difficult, and the devil is always in the details. In the latter section of my Part 1 video, and in all of my Part 2 video, I discuss a new peer reviewed scientific paper called “How do intermittency and simultaneous processes obfuscate the Arctic influence on midlatitude winter extreme weather events?”.

Since extreme weather events are presently affecting billions of people around the planet, getting at the details is vitally important, in fact it was mentioned that there were 146 recent papers looking into the details of these connections. There is a lot of complexity and confusion, and the connections vary critically depending on the season, for example late fall/early winter the lack of Arctic sea ice in the Barent-Kara Sea, the Chuckhi-Beaufort Sea, and Baffin Bay have been connected to extreme winter cold and snowfall in Eurasia, extreme weather conditions in North America, etc… In late winter, the Stratospheric Polar Vortex often radically undergoes Sudden Stratospheric Warming, leading to large outbreaks of cold Arctic air infiltrating into much lower latitudes in North America and Eurasia.

Clearly, we still have a lot to learn, but it seems impossible to me that rapid Arctic changes can occur without having profound effects on lower latitude weather extremes. I think these connections will become more obvious and resolved as we get closer and closer to complete loss of Arctic sea ice within the next few years.

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About paulbeckwith

Well known climate science educator; Part-time Geography professor (climatology, oceanography, environmental issues), University of Ottawa. Physicist. Engineer. Master's Degree in Science in Laser Optics, Bachelors of Engineering, in Engineering Physics. Won Association of Professional Engineers of Ontario gold medal. Also interested in investment and start-ups in climate solutions, renewable energy and energy efficiency. Avid chess player, and likes restoring old homes. Married with children.
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