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Extreme weather lowers global crop yield

Drought-affected corn in eastern Colorado, via Colorado State University.
Drought-affected corn in eastern Colorado, via Colorado State University.

A study published in the journal Nature on January 7, 2016, provides evidence that historic trends of extreme weather lowers crop production at a global scale.

Corey Lesk and colleagues used a unique statistical approach on data available from the Food and Agriculture Organization of the United Nations (FAO). They considered not only extremely high temperatures, but also drought, flooding and severe cold. They looked at how those climate anomalies affect cereal grain production and concluded that extreme heat and drought between 1964 and 2007 account for about a 10% decline in global cereal crop production.

Another novel aspect of their study is to include measures other than yield – amount of grain produced by the plant – to consider the entirety of crop production. An insight gained from this approach is that – while developed countries suffer the most total crop losses due to weather extremes – this is because those countries tend to have more advanced agriculture, therefore producing more crops per hectare, ergo a greater total yield loss due to a single event. That does not necessarily mean as significant a loss for deliverable crops that would be experienced in regions like sub-Saharan Africa, that face greater challenges to get food to market.

In sum, weather extremes can disproportionately affect areas that already struggle with food security.

Interestingly, flooding and severe cold were not significant factors in crop production declines at a national level. The authors explain those results are likely seasonal effects, because floods tend to happen in spring months before many crops are planted, and severe cold is normally experienced in winter months when crops are not being grown.

However, heat-waves more commonly occur during a growing season, which can compromise yield.

Droughts may be even more significant because those events can persist for months or years, interfering with multiple crop harvests, and decreasing the amount of land that can be cultivated, which could drastically depress crop production.

Bottom Line: An analysis of Historic data shows that ongoing drought and extreme heat has a negative impact on crop production.

Read the study in Nature

January 18, 2016

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