Agricultural Degradation

Newly identified jet-stream pattern could imperil global food supplies, says study

<embed>https://phys.org/news/2019-12-large-atmospheric-jet-stream-global.html</embed>

The wave-5 patterns tend to hover over central North America, eastern Europe and eastern Asia; the wave-7 patterns over western-central North America, western Europe and western Asia. In both cases, the results are the same: hot air swirls up from the south into the peaks, producing abnormal spikes in temperature that can go on for weeks. This in turn reduces rainfall, dries up soils and vegetation, and kills crops in each region. 

Scientists have identified systematic meanders in the globe-circling northern jet stream that have caused simultaneous crop-damaging heat waves in widely separated breadbasket regions-a previously unquantified threat to global food production that, they say, could worsen with global warming. The research shows that certain kinds of waves in the atmospheric circulation can become amplified and then lock in place for extended periods, triggering the concurrent heat waves. Affected parts of North America, Europe and Asia together produce a quarter of the world food supply. The study appears this week in the journal Nature Climate Change.

"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," said lead author Kai Kornhuber, a postdoctoral researcher at Columbia University's Earth Institute. "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."

Changing risks of simultaneous global breadbasket failure

<embed>https://www.nature.com/articles/s41558-019-0600-z</embed>

The risk of extreme climatic conditions leading to unusually low global agricultural production is exacerbated if more than one global ‘breadbasket’ is exposed at the same time. Such shocks can pose a risk to the global food system, amplifying threats to food security, and could potentially trigger other systemic risks1,2. While the possibility of climatic extremes hitting more than one breadbasket has been postulated3,4, little is known about the actual risk. Here we combine region-specific data on agricultural production with spatial statistics of climatic extremes to quantify the changing risk of low production for the major food-producing regions (breadbaskets) over time. We show an increasing risk of simultaneous failure of wheat, maize and soybean crops across the breadbaskets analysed. For rice, risks of simultaneous adverse climate conditions have decreased in the recent past, mostly owing to solar radiation changes favouring rice growth. Depending on the correlation structure between the breadbaskets, spatial dependence between climatic extremes globally can mitigate or aggravate the risks for the global food production. Our analysis can provide the basis for more efficient allocation of resources to contingency plans and/or strategic crop reserves that would enhance the resilience of the global food system.

Climate change will make hundreds of millions more people nutrient deficient

<embed>https://www.theguardian.com/science/2018/aug/27/climate-change-will-make-hundreds-of-millions-more-people-nutrient-deficient</embed>

Previous research has shown that many food crops become less nutritious when grown under the CO2 levels expected by 2050, with reductions of protein, iron and zinc estimated at 3–17%.