Home ›› 06 Dec 2022 ›› Opinion
There are endless ways the natural world, incredibly complex and dynamic as it is, can threaten society’s wellbeing, and we continue to learn more and more about them, especially as the planet changes under human influence.
Scientists are only now beginning to understand one specific natural hazard that works on an immensely large scale and has potential to cause global disaster. The risk is known as Jetstream-induced concurrent failure of multiple global bread-baskets. It is but one component of a broader risk known as multi-breadbasket failure.
For most of history, people relied on food produced in their local region. Only cash crop luxuries like sugarcane or tea could be often exported from far away. But now, we live in a highly globalized world where production of humanity’s food is centered around just a few major agricultural regions, located mostly in developed countries and (important later on) at temperate latitudes. In particular, wheat, corn, and rice, the three grains making up half of all food produced, are mostly grown in a handful of regions, the so-called breadbaskets, mainly located in wealthy countries like the United States, Canada, China, Russia, Ukraine, Australia, and Argentina, which also export much of the world’s food. Many other, especially developing, countries, rely a great deal on food imports, not to mention aid in times of crisis. The benefit is that, unlike in the old days, when crop failures in a particular area left local populations vulnerable to famine, now a country facing food shortages can receive food from elsewhere. And if a major food-exporting nation experiences a drop in production or export, another nation can fill in the gap.
The downside is that this worldwide food supply network can break down. And that poses a grave risk to populations dependent on imported food. It has been especially the case the past three years due to COVID-19. Reaction to pandemic caused a rapid drop in international trade. It now leaves lingering supply chain disruptions, accompanied by a global energy crisis also hampering food availability. Another threat is crop diseases that can spread rapidly through trade routes, like the dreaded Ug99 wheat rust. There is also the increasing risk, thanks to climate change, of severe weather hitting food production in both poor and rich countries, leaving former in need of imports while preventing latter from exporting food (another common sight these past three years.) The danger is especially great if such disasters occur in several breadbaskets at the same time. Such a scenario means the world’s breadbaskets collectively have far less food to deliver.
However, it takes a major bout of bad weather to impact a whole season’s production in a vast region like the American Midwest or the Eurasian steppe (Russia and Ukraine.) The chances of it happening somewhere in any given year is still rather low, so it happening simultaneously in two select regions should be far lower, and three regions lower still. And quite a lot of territory, widely dispersed across the world, serves the role of breadbasket. So globalization should save us in the end. But actually, it isn’t so. Simultaneous breadbasket weather shocks have happened in recent years. They are happening as I write. And there are good reasons for this kind of event to be more common than if only decided by random chance.
For starters, extreme weather is not equally distributed in time. It often becomes more prolific worldwide during major El Nino or La Nina events. We are in one such La Nina period, already three years long, a very rare duration. But an even more important factor is at play here. If you look at all the world’s breadbaskets on a map, the US corn and wheat belts, Canadian prairies, Russian and Ukrainian steppe, South American pampas, China’s Yangtze and Yellow River basins, and Australia’s Murray-Darling Basin, you clearly see one thing they all have in common, their location in Earth’s middle latitudes, especially temperate regions. This means all the breadbaskets share similar climates, which makes sense. But going beyond that, it turns out all the middle latitude regions also share strong tele-connections, when weather processes in one part of the world influence weather in another, often in the form of a far-reaching atmospheric system.
The most important of such systems are the Jetstreams, high-altitude currents of air that encircle the globe, flowing west to east at high speed. In both the northern and southern hemisphere, a subtropical jet and a stronger polar jet girdle the temperate latitudes, but not evenly. Undulations in the Jetstream known as Rossby waves push weather systems north and south and sometimes hold them in place, the cause of most breadbasket disasters. The bigger such waves are, the slower they move and can even stall. Rossby waves encircling the globe, usually when they number 5 or 7, can intensify each other by a phenomenon called quasi-resonant amplification. In the northern polar jet, this can unleash extreme drought, heat, cold, wind, and flooding across North America, Europe, and Asia. Plus, an El Nino or La Nina can cause an outbreak of amplified waves the entire year. All this means that one single event can induce harvest disruption in every breadbasket at once.
Now we know just how serious the risk is. The fact is, the regions of highest agricultural productivity are all located next to the Jetstreams. This is likely not a coincidence. Temperate climates seem most suited for growing crops and the Jetstreams themselves probably spurred the advancement of civilization (maybe because technological and social innovation was needed to cope with weather swings). So here, we see a deep connection. A particular environment is responsible for high agricultural productivity and this same environment will respond to climate change in such a way as to cause massive damage to same productivity, like how most global commercial activity is located near the coast, hence can be wiped out by rising sea levels.
Amplified Rossby waves, made more likely by climate change, are major cause of our troubles. They were abundant during the La Nina years of 2010-2012. 2010’s global weather activity, particularly a Russian heatwave, was so bad that it caused 2011’s food price hike. The Jetstream also went haywire in 2018, bringing disaster across Europe, North America, and East Asia. From 2020, things started to really go downhill. In 2021, a wildly meandering Jetstream produced USA’s February freeze, USA and Canada’s July record heatwave, and Europe’s extreme floods the same month. Paraguay, Uruguay, southern Brazil, and northern Argentina, together comprising South America’s most productive agricultural region, suffered extreme drought. Severe weather hit Australia throughout the year, including floods near the end that wiped out crops worth billions of dollars.
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