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A new study finds that widely-used climate models have a blind spot for how extreme weather events affect food production when multiple regions are hit at the same time, thereby underestimating the threat that climate change poses to global food security.
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As global greenhouse gas concentrations increase, “we are entering this uncharted water where we are struggling to really have an accurate idea of what type of extremes we’re going to face,” said lead author Kai Kornhuber, a researcher at Columbia University and the German Council on Foreign Relations, whose team looked at the likelihood that several major food producing regions could simultaneously suffer low yields.
“We show that these types of concurring events are really largely underestimated.”
The rising intensity and frequency of extreme weather can lead to price spikes, food insecurity, and even civil unrest, Kornhuber and his colleagues found. It can be devastating for communities in major food producing regions, and for countries that for countries that depend on imports. When multiple instances of extreme weather happen simultaneously in different regions, the combined impact can be worse than isolated events, finds the study published in Nature Communications.
In mid-latitude regions, “concurrent weather extremes” are generally driven by atmospheric wave patterns in the jet stream. Extreme heat and rainfall can be linked, and can be triggered to occur at the same time across growing regions. When a single, large, stagnant weather pattern altered the jet stream and disrupted the normal movement of weather systems in 2010, it caused extreme heat where a hot air mass was trapped over western Russia while moving moist air to create flooding in Pakistan.
“Think of the atmosphere like a loose membrane,” William Lau, an atmospheric scientist at NASA’s Goddard Space Flight Center, explained at the time. “If you push one part up, something else has to come down somewhere else. If you produce a high in one region, you produce a corresponding low in another.”
In this case, the effects of the atmosphere rebalancing itself from a single meteorological disruption created simultaneous extreme weather events in two regions located 1,500 miles apart. In both regions, the bad weather caused massive crop losses, leading to a rise in global food prices and civil unrest.
Some analysts caution that the outcomes were worsened by the influence of market economics on the global food system, which caused greater losses through land-degrading farming practices and made food less accessible through exaggerated price increases.
Previous research has analyzed the impact of changes in wave patterns within given regions, but did not measure the impact on food yields at a global level across breadbasket regions.
For the new study, Kornhuber’s team used observational and climate model data from 1960 to 2014 and projections for 2045 to 2099 to look at jet stream modeling and how it is linked to past simultaneous crop failures. The analysis projected “strong meanderings” of the jet stream that can cause higher heat extremes than previously realized. The projections show “an elevated risk of simultaneous crop failures that could cripple the global food supply chain by triggering crop failures in key breadbasket regions such as India, the United States, and Eastern Europe,” explains Vice.
The findings indicate that climate models tend to underestimate the risks of concurrent extreme weather events, which can lead to “blind spots” in awareness about the implications of changing weather patterns.
Kornhuber said the study should be “a wake-up call in terms of our uncertainties” on the impacts of climate change on the food sector as weather extremes become more frequent, intense, and likely to occur at the same time.
“We need to be prepared for these types of complex climate risks in the future,” he said, “and the models at the moment seem to not capture this.”