Evaluating the 2019 NARO-APCC Joint Crop Forecasting Service yield forecasts for Northern Hemisphere countries

Abstract:

Forecasting global food production is of growing importance in the context of globalizing food supply chains and observed increases in the frequency, intensity and duration of climate extremes. The National Agriculture and Food Research Organization (NARO) - the Asia-Pacific Economic Cooperation (APEC) Climate Center (APCC) Crop Forecasting Service aims to contribute to food production forecasting activities. The service provides yield anomaly forecasts for global cropland areas on a monthly basis, and 1 year of testing the operation of the service was recently completed. The present study evaluates the forecast skill of the NARO-APCC forecasts for the 2019 yields of major commodity crops. The NARO-APCC yield anomaly forecasts are converted into yield forecasts through postprocessing and then compared with the reported yields and forecasts from different organizations, i.e., the European Commission’s Joint Research Centre (JRC) and the United States Department of Agriculture (USDA). Forecasts for maize, wheat, soybean and rice were evaluated for 20 countries located in the Northern Hemisphere, including 39 crop-producing states in the US, for which 2019 reported yields were already publicly available. The NARO-APCC forecasts become available one to several months earlier than the JRC and USDA forecasts. The forecast skill of the NARO-APCC forecasts was good in absolute terms, but the forecast errors in the NARO-APCC forecasts were almost always larger than those in the JRC and USDA forecasts. The forecast errors in the JRC and USDA forecasts decreased as the harvest approached, whereas those in the NARO-APCC forecasts were rather stable over the season, with some exceptions. Although this feature seems to be a disadvantage, it may turn into an advantage if skilful NARO-APCC forecasts are achievable in the earlier stages of a season. We conclude by discussing potential ways to further improve global yield forecasting.