The winding jetstream

Via ClimateCrocks.

Winding jetstream, June 22 2019

Michael Mann in Scientific American:

During the extreme events I noted, the jet stream acted strangely. The bends went exceptionally far north and south, and they stalled—they did not progress eastward. The larger these bends, the more punishing the weather gets near the northern peak and southern trough. And when they stall—as they did over the U.S. in the summer of 2018—those regions can receive heavy rain day after day or get baked by the sun day after day. Record floods, droughts, heat waves and wild fires occur.

My collaborators and I have recently shown that these highly curved, stalled wave patterns have become more common because of global warming, boosting extreme weather. But we predict that the rising severity may level off for the next several decades. That may sound strangely “good”—the bad spells will continue, but at least they will not get worse. We also predict that the extreme events will start becoming much more severe, beginning around 2050 or so—particularly in summer. Threats to people’s health and safety will increase, storm damage will get more extensive and crops needed to feed a rising population will be ruined.

How do we know? Wave mathematics and quantum mechanics tell us. Yes—the mathematics that characterize the behavior of electrons at the smallest scale help us describe the behavior of our atmosphere at global scales. They indicate that the rise in dangerous weather, the coming plateau and the subsequent surge are driven by a curious trade-off between greenhouse gas concentrations from fossil-fuel burning and sulfur pollution from industrial smokestacks. And that trade-off raises the question of whether cutting emissions will prevent the jet stream from wreaking havoc.

Every year we delay reducing CO₂ emissions increases the likelihood of extreme weather.  It's not just that temperatures are rising.  The swings are getting bigger, too.