Climate variability

How does climate variability contribute to global crop failures?


According to a recent paper published on July 3 in the journal Scientists progress (1). For example, in 1983, ENSO was responsible for the largest synchronous harvest failure in recorded modern history.

Globally synchronous harvest failures refer to the simultaneous failure of a single harvest in several as far apart as the United States, China, and Argentina. And many researchers predict that these events will become much more frequent due to climate change. So how important is the risk of potential failures on a global scale for food security?

Current models of the global agricultural system assume that crop failures in geographically remote areas are unrelated. However, the new findings suggest that to make global food systems more robust, we need to learn more about the most damaging consequences of so-called multiple “breadbasket” failures. Especially since about two-thirds of the world’s staple foods are produced by about 25 percent of the planet’s cropland. And fewer people than ever have insufficient access to enough food, the authors write. In addition, an increasing number of people depend on imported food to meet their minimum daily caloric needs.

Researchers at Columbia University’s International Institute for Climate and Society Research, in collaboration with the International Food Policy Research Institute (IFPRI), assessed how different modes of climate variability cause volatility in global and regional agricultural yields. The study is the first to estimate the extent to which different modes of climate variability influence the volatility of global and regional agricultural production.

In particular, they examined the impact of ENSO, the Indian Ocean Dipole and other well-understood climate models on global production of maize, soybeans and wheat. More specifically, they analyzed how these modes of climate variability influenced drought and heat in the main growing regions.

Globally, maize is the most sensitive to climate variability, which accounts for about 18% of the year-to-year variation in maize production. While only 7% and 6% of the variation in soybean and wheat yields is linked to changes in global productivity, and therefore are less at risk of simultaneous failures.

The researchers also found that the risks are greater for poor farmers in developing countries who lack adequate coping mechanisms and lack the infrastructure and resources to handle large fluctuations in crop yields.

In addition, certain geographic regions, such as Africa and Brazil, are more exposed to the perils of climate variability. For example, ENSO and other recurring climatic phenomena account for 40 to 65% of the variation in food production in Africa and northeastern Brazil, the authors report. While other regions experience fluctuations closer to 10 percent.

Despite these large differences, the results reveal a definite link between climate models in several regions. Additionally, the authors suggest that these results can be extended to monitor and possibly even predict the influence on global production and potential global crop failures.

(1) Anderson, WB et al. Synchronous poor harvests and climate-driven variability in production. Scientific advances (2019). DOI: 10.1126 / sciadv.aaw1976


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