“Concerning” Pattern Sets Up in Jet Stream

June 15, 2022

Planet wide alignment of the jet stream could be setting up extremes just when we really don’t need them.

Scientific American, December 9, 2019:

During the summer of 2018, the future of climate change became the present. Highly amplified jet stream patterns remained stuck in place for unusually long periods of time, bringing the planet an onslaught of remarkable weather catastrophes—for example, unprecedented heat waves and drought in East Asia and Northern Europe, the start of the deadliest and most expensive fire season on record in California, and Japan’s deadliest floods since 1982.

The extreme summer weather helped bring the 2018 tally of billion-dollar weather-related disasters to 39–the fourth highest such total for any year since 1990, according to insurance broker Aon Benfield. Among these were seven billion-dollar droughts–the highest number of billion-dollar droughts on record (previous record: six in 1999 and 2015). Total damages from drought in 2018 were near $33 billion—tied for the fifth-highest level of global drought damage since 1975.

Unfortunately, extreme jet stream patterns like those of 2018 may be getting more common and more extreme, representing a significant danger to global food security. An April 26 paper, Extreme weather events in early summer 2018 connected by a recurrent hemispheric wave-7 pattern, by climate scientist Kai Kornhuber of Columbia University and co-authors, found that the 2018 extremes were associated with a particular mode of “stuck in place” jet stream behavior—one that has increased in frequency and persistence in recent decades.

A just-published December 9 follow-up study, Amplified Rossby waves enhance risk of concurrent heatwaves in major breadbasket regions–also led by Dr. Kornhuber–found that stuck jet stream patterns like seen in 2018 are prone to bringing simultaneous heat waves and associated drought conditions to multiple important grain-producing regions of the world. The authors wrote that these stuck jet stream patterns can cause “reductions of 4% in crop production in the affected regions, with regional decreases up to 11%. Given the importance of these regions for global food production, the identified teleconnections have the potential to fuel multiple harvest failures posing risks to global food security.” (A teleconnection is a causal connection or correlation between meteorological phenomena which occur a long distance apart). 

In a press release that accompanied the most recent paper, Dr. Kornhuber said, “We found a 20-fold increase in the risk of simultaneous heat waves in major crop-producing regions when these global-scale wind patterns are in place. Until now, this was an underexplored vulnerability in the food system. During these events there actually is a global structure in the otherwise quite chaotic circulation. The bell can ring in multiple regions at once.”

Kai Kornhuber on Twitter:

Figure from the SI of our 2019 ERL paper on the 2018 heatwave with examples of past occurrences. See how winds and temperatures align.


2 Responses to ““Concerning” Pattern Sets Up in Jet Stream”

  1. rhymeswithgoalie Says:

    Meanwhile there are hot spots being set up in the far north (like the Yamal Peninsula) that have to be melting a lot of permafrost.

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