EU Science Hub

Forecasting wheat yields under extreme weather conditions

Extreme weather events can seriously impact crop yields
Oct 18 2018

A JRC article published in Scientific Reports today assesses the quality of wheat forecasts during years with extremely low or high yields, and calls for improvements based on near real-time data fusion.

Timely forecasts of crop failure, bumper years, or just average crop production levels is crucial to allow producers, exporters, importers, traders, and companies to make informed decisions to ensure food security and economic continuity. This is particularly evident in recent years, where extreme and sometimes unprecedented weather across Europe has seriously impacted crop production. For example, exceptional autumn and spring conditions in 2016 reduced France’s wheat production by 8 million tonnes, nearly a third of expected production levels (Ben-Ari et al., 2018).

The negative impact of different types of extreme weather on crop production depends on the growth stage of the crop. Crops are particularly susceptible during the flowering stage. Negative impacts on crop production can result from short periods of frost or heat, or heavy rainfall, or from extended periods of drought. Crop production levels can be significantly reduced due to direct damages and/or through outbreaks of pests and disease. The knock-on effects of such losses can affect food prices and availability.

The JRC article evaluated 440 crop-yield forecasts in 25 European Union (EU) Member States for the period 1993-2013. It found that in years with high crop yields, forecasts generally underestimated the final yield, even though they gradually improved during the season. In years with low yields, yield forecasts for July were overestimated by about 10%. Crop-yield reductions due to drought conditions were forecast with lead times of 2 months.

Significant crop production losses across the EU occurred due to record-low wheat yields in several EU countries in the years 2003, 2006, 2007, 2011 and 2012. These losses were mainly due to drought and/or heavy precipitation caused by large-scale weather systems. The impacts of such weather systems can affect many countries and different parts of Europe at the same time. For example, in 2007 and 2012, eastern countries were hit by severe drought conditions, while western countries experienced problems triggered by heavy rainfall. The forecasts in such years were found to underestimate the impacts on crop yields by 10.4 to 78.4%.

The authors conclude that crop yield forecasting will have to improve to be able to cope with increasingly unprecedented weather conditions. Faster computation should enable more timely and improved use of near-real-time information from crop models combined with Earth observations by the Copernicus Sentinel satellites.

The JRC has been forecasting crop yield and production levels of all major crops in all Member States of the European Union since 1993. The European Commission's Directorate-General for Agriculture (DG AGRI) shares the JRC forecasts through the Agricultural Market Information System in order to enhance global food market transparency.

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