"The study shows that measures need to be taken to safeguard food supply in bad years and also to make the most of good years. Actions range from targeted crop management through to crop insurance and management of food storage," says Andy Challinor. (Credit: United Soybean Board/Flickr)

To protect global crops, keep tabs on El Niño

Findings that link El Niño with global fluctuations in crop yield offer a new tool for adapting food security to climate change, report researchers.

“The IPCC Fifth Assessment Report highlighted that we expect a decrease in the year-to-year stability of our food supply and that we need to act now to safeguard food production in the future,” says study coauthor Professor Andy Challinor of the School of Earth & Environment at the University of Leeds.

“This new work tells us that we can predict when the bad years will be, ahead of the harvest.”

Previously, the reliability of seasonal crop yield forecasts had been insufficient for mid- and high-latitude regions due to weaker influences of the tropical oceans and because some crops in these areas are more greatly influenced by soil water content than temperature.

Because the prediction of El Niño and the lesser-known La Niña—warming and cooling, respectively, of the sea surface temperatures in the tropical Pacific—are highly accurate, they could be used to improve the harvest forecast of crops in those areas.

In the new study, which appears in Nature Communications, researchers find that in both El Niño and La Niña years the global mean yield of corn, rice, and wheat is much lower than normal. The response of the soybean yield in La Niña years is unclear, but the study finds an increase in El Niño years.

The research also shows that the region in which La Niña negatively affects the yield of crops is smaller than the region affected by El Niño—the negative impacts of La Niña affect 9 to 13 percent of harvested areas worldwide, compared to 22 to 24 percent for El Niño.

However, unlike El Niño years, the area that is affected in a positive way in La Niña years is much smaller than the region that is affected negatively—only two to four percent of harvested areas worldwide.

“The El Niño remains a concern for regions where crop production is negatively affected, but we need to pay more attention to La Niña from a food trade point of view,” says lead author Toshichika Iizumi from the National Institute for Agro-Environmental Sciences in Japan.

“The study shows that measures need to be taken to safeguard food supply in bad years and also to make the most of good years. Actions range from targeted crop management through to crop insurance and management of food storage,” adds Challinor.

Source: University of Leeds

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