A new research report suggests climate models have badly underestimated the potential impact of multiple mass crop failures on the planet and as driven from the highest levels in the atmosphere, as global heating accelerates.
Illustration showing the major jet stream patterns that encircle the globe. As a recent study illustrates, these patterns have far more influence on global crop problems than previously understood. The patterns are also highly unstable, morphing rapidly into far different shapes based on heat domes and other climate issues manifesting at the planetary surface. Image: Lyondon State College of Meteorology, Public Domain
As has already been observed, the hotter world created by the climate crisis can rapidly transform the most verdant and productive of agricultural pastures into barren landscapes.
Those rapid shifts can happen through a combination of high heat with low rainfall at one extreme, or atmospheric rivers delivering deluges powered with high winds at another. Regardless of the cause, the end results are the same: fertile lands and their carefully tended microbiomes destroyed, crops lost possibly for multiple seasons, and food shortages.
Those shocks to global food security can be tracked as they develop and forecast to some degree as they have grown more common. But one flaw in modeling to date has been considering what could happen when more than one serious food security shortage hits the planet due to the climate crisis at the same time. A second and related one is to understand better how biases in how climate models are designed underestimate the likelihood of concurrent climate events which could trigger a catastrophic collapse of much of our food production capacity.
That is the focus of a just published analysis by a team of scientists from the United States and Germany.
The work began by utilizing one of the most sophisticated models to understand agricultural production variances under various sorts of global climate stress. That analytical construct is the Global Gridded Crop Model Intercomparison (GGCMI). Then they set the model to focus on areas which are responsible for over 70% of international production of wheat, and others which yield over 66% of all global maize (corn) production, both major crop staples in large areas on most continents. Then they studied how the interaction of conventional climate change models matched up to actual historical results of global crop events during the period from 1960 to 2014, the period of the study as well as the period in which rapidly intensifying global climate shifts became more common.
They then matched that with projections as to what we might expect throughout the rest of the century, with models covering the period from 2045 to 2099.
The scientists looked at issues such as whether upper atmospheric jet patterns and surface weather anomalies were properly correlated in the models, to look at how a particular type of climate influencing phenomenon might manifest on a broad swath of landscapes around the planet. They also looked at wave events, such as heat waves and — over time at least — pulsating heavy rainfall patterns, and how these far more common events today were properly considered — or not — in both the crop models and climate models.
They also then evaluated what happens when, as appears to be what is happening in today’s world more than we properly track, the resultant food shortages that follow hit us hard at the same time.
As Kai Kornhuber, lead author of the new study and researcher Columbia University and the German Council on Foreign Relations, noted, global heating is terraforming our planet in ways even those closest to the problem are having trouble anticipating.
Though pumping higher “concentration[s] of greenhouse gases [into the atmosphere],” he noted in a recent interview about his team’s work, “we are entering this uncharted water where we are struggling to really have an accurate idea of what extremes we’re going to face.”
One of the major discoveries they made during this analysis came from taking a hard look at the behavior of the jet stream, a high-speed air pattern which moves in segments thousands of miles long at the boundary of the highest levels of the atmosphere, near the stratosphere-troposphere boundary at the highest levels where air still exists. Though these winds blow fast, the air had been considered sufficiently thin — just as a “gut” level assumption — that they could not possibly have a big impact on large scale climatic cycles happening down at the surface level of the Earth.
What the researchers found was that the “strong meandering” large scale wave structures common in the jet stream have strong correlative influences on large regions of some of the most important crop-producing areas in the world. Those regions, studied for this effort within North America, East Asia, and Eastern Europe, were found to suffer harvest losses of as much as seven percent just from the jet stream movements alone. That, combined with other climatic factors to amplify the situation at ground level, was then discovered to be connected to nationwide and sometimes entire continent-wide simultaneous crop failures around the globe.
One of the many examples cited in the study happened in 2010. When the jet stream began fluctuating in powerful wide regions high just below the troposphere that year, powerful floods ripped across large agricultural regions in Pakistan, while record surface temperatures spread within Russia. Both were events which happened both at the highest of altitudes and on the ground simultaneously over wide areas, with the surface-level effects causing widespread crop failures.
When the researchers compared their finding to what conventional climate and geophysical wind models were fairly accurate at predicting and modeling the movement of the jet streams high overhead, they were of little use in demonstrating the connection between those jet stream wind shifts and the devastating crop failures happening on the ground.
Though it had not happened when the research Kornhuber’s team was conducted, the recent waves of heat which slashed downwards across the southern United States and into northern Mexico in the past weeks were shown to link to high-altitude wind events. So too were the atmospheric river pushes into the Pacific Northwest and eastern Canada multiple times in the last few years. And so also were the heat domes which created massive drought throughout Europe both last year and already happening this year, all of which were accompanied by high-altitude wind pattern effects including localized versions of the jet stream.
In commenting about his team’s learnings, Kornhuber explained that what they learned should be considered “a wakeup call in terms of our uncertainty and the impacts of climate change on the food sector, with more frequent and intense weather extremes and increasing complicated combinations of extremes.”
“We need to be prepared for these types of complex climate risks in the future,” he continued. “The models at the moment seem to not capture this.”
The technical paper covering this research, “Risks of synchronized low yields are underestimated in climate and crop model projections,” by Kai Kornhuber, et. al., was published in the open access journal Nature Communications on July 4, 2023.