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So, what& #39;s happening in the Arctic now is kinda crazy, but also really important to extreme weather throughout the northern hemisphere. Read my piece today on the topic, but here& #39;s a Thread: https://yaleclimateconnections.org/2020/10/warmer-climate-and-arctic-sea-ice-in-a-veritable-suicide-pact/">https://yaleclimateconnections.org/2020/10/w...
First, the basics: there& #39;s a "positive feedback" (positive in the negative sense, Trump would say), like a mutually destructive relationship. Warming melts ice & snow in the Arctic, making the surface less reflective -> absorb more sunlight -> warm more -> melt more -> etc. 1/n
As a result, the Arctic is warming 3x faster than the global avg, and sea ice is disappearing fast. Half Arctic sea ice surface area and 75% of its volume disappeared in summers between 1979 and 2012.
Then 2014–2020 were the 7 hottest years on record. Guess what happened? 2/n
Then 2014–2020 were the 7 hottest years on record. Guess what happened? 2/n
Polar scientists kept expecting a new record summer minimum Arctic sea ice low, but no! There were new record lows in winters and springs, but something kept happening in August/September to preserve some ice and prevent a new summer minimum record. 3/n
The 2012 summer Arctic sea ice minimum record still stands, as this great visualization from @ahaveland illustrates 4/n https://www.youtube.com/watch?v=oSrWcsaCnkg&feature=emb_logo">https://www.youtube.com/watch...
So, what the hell? The hell, posit Jennifer Francis and Bingyi Wu in a new paper, is that the melting Arctic snow and ice are disrupting the jet stream, often causing low-pressure cloudy systems to linger in the Arctic in Aug/Sep, keeping temps cool & winds spreading the ice 5/n
But this doesn& #39;t happen every year. It didn& #39;t happen in 2019 and 2020, which, as you can see in the @ahaveland video above, both nearly broke the summer sea ice minimum record. The melting snow & ice are ironically creating conditions to preserve some summer sea ice, but...6/n
This effect is only enough to temporarily slow the & #39;Arctic sea ice death spiral.& #39; Global warming is relentless, whereas the summer cloudy Arctic weather systems are sporadic. Another new paper predicted ice-free Arctic summers beginning somewhere between about 2030 and 2050 7/n
So what& #39;s up with the jet stream? The temp difference between the Arctic & lower latitudes creates a force that moves it along. Like a river current, air currents tend to go straight when fast & meander when slow. Faster warming in Arctic = less temp diff = slower jet stream 8/n
Slower, wavier jet steam means the air current doesn& #39;t move weather systems along, so they tend to get stuck in the jet stream waves. Like the low-pressure cloudy summer Arctic systems, but also high pressure systems in Scandanavia, Canada, etc., creating nasty heatwaves 9/n
Other papers have linked these Arctic-connected wavy jet stream patterns to winter high-pressure ridges off the coast of California, like the one that contributed to the state& #39;s worst drought in a millennium in 2012–2016, or the one that caused Europe& #39;s deadly 2003 heatwave 10/n
There are lots of other examples in this 2018 study led by @MichaelEMann of these & #39;quasi-resonant amplification& #39; jet steam wave events being connected to extreme weather events (11/n): https://advances.sciencemag.org/content/4/10/eaat3272">https://advances.sciencemag.org/content/4...
There& #39;s a fast-growing body of climate science research on these connections between changes in the Arctic, the jet stream, and extreme weather events getting stuck. Hurricanes may even be slowing down & wreaking more havoc as a result, though we need more research on that (12/n)
Anyway, it& #39;s all very fascinating stuff. To abuse the cliché, what happens in the Arctic doesn& #39;t stay in the Arctic. Now, if you haven& #39;t yet, read my article! (13/13) https://yaleclimateconnections.org/2020/10/warmer-climate-and-arctic-sea-ice-in-a-veritable-suicide-pact/">https://yaleclimateconnections.org/2020/10/w...
