Planet waves, and the big heat

It’s certainly hot in the southwestern USA at the moment — a dome of heat has established itself under a persistent high pressure ridge, and temperatures are pushing up towards all-time highs. Wildfires are running out of control. One caused the tragic death of 19 firefighters at Yarnell Hill in Arizona yesterday. One more extreme weather event to add to this year’s growing list, and as with most of the others, there’s a clear sign of a link with rapid climate change. That heat dome is being held in place by a large, slow-moving northward loop in the jetstream — and that jetstream pattern is beginning to look very much like the characteristic fingerprint of rapid warming in the northern hemisphere, as Jennifer Francis explains in this video, recorded at a Climate Desk event in Washington last month. It’s just about the clearest explanation of what’s going on that I’ve encountered — particularly in her description of why the jetstream exists in the first place, and why warming is changing the way it behaves. If you want to understand what’s going on, you have to watch this.

There’s a full recording of the Climate Desk event here, including a talk by Weather Channel meteorologist Stu Ostro. Ostro used to be a confirmed sceptic, but began to see changes in weather patterns that he traced back to the effects of warming — specifically, an increase in the “thickness” of the atmosphere, the very thing that’s driving the changes in jetstream behaviour.

The Bast Effect: summertime in wintertime

Forget the Gore Effect1, Chicago — and much of the eastern half of the continental USA — is now experiencing the Bast Effect — a record March heatwave in the Heartland of climate denial. The figures for this heatwave are truly extraordinary. Here’s Jeff Masters:

For the third consecutive day, Chicago, Illinois hit their warmest temperature on record so early in the year, going back to 1872. The mercury hit 82°F, giving the city its third consecutive day of 80°+ temperatures, smashing the old record by a month. Previously, the earliest Chicago had ever seen three consecutive 80 degree days was back on April 14 – 16, 1976.

Masters quotes the National Weather Service:

Chicago and Rockford have both broken high temperature records 3 days in a row and will likely break record highs for 5 days in a row. There is even the potential they could tie or break record highs for 6 or 7 days in a row depending on how warm temperatures get on Monday and Tuesday. It is extraordinarily rare for climate locations with 100+ year long periods of records to break records day after day after day. At the current pace… it is likely that Chicago and Rockford will not only break… but shatter their current record warmest Marches.

Joe Romm at Climate Progress has a very useful overview of the event, drawing heavily on the views of Masters and the Weather Channel’s Stu Ostro.

Even the most committed US denier can’t fail to notice midsummer weather happening in March, coming on top of a very mild winter. This is exactly the sort of extreme weather event that can drive public opinion in the direction of the need for action. It’s large, widespread and not too damaging (so far), yet undeniable. One can only hope that US politicians notice. And it might be a good idea to invite Bast to give a few talks outside Illinois…

[Badly Drawn Boy]

  1. The occurrence of cold weather in a place where Al Gore talks about global warming []