Studies of significant changes to the Jet Stream—a fast-moving river of air that plays a major role in regulating climate patterns—show increasing risk of prolonged catastrophic drought and threats to the human food supply. Scientific American is reporting:
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 follow-up study, published in December, 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.
Dim Coumou, one of the study’s co-authors, described risk posed by the new Jet Stream patterns—called Rossby waves—this way:
Normally, low harvests in one region are expected to be balanced out by good harvests elsewhere. These waves can cause reduced harvests in several important breadbaskets simultaneously, creating risks for global food production.
When specific Rossby waves displace expected climate conditions, they can undermine the ability of natural systems to return to normal in a timely way. Persistence of these “stuck-in-place” displacements can fundamentally disrupt sensitive natural systems dependent on specific climate conditions.
As global heating continues to intensify, the occurrence of disruptive Rossby waves is expected to increase, meaning the potential for failure of multiple breadbasket regions will not only increase, but could become commonplace. There is no precedent in recorded human history for such a global simultaneous threat to food production.
The key news item here is that the human food supply is at risk, due to global heating, and so aggressive action to mitigate climate disruption risk is warranted. Decarbonizing energy systems, industry, transportation, and agriculture, is an imperative, as is the work of building resilience against shock events.