Climate change will worldwide affect both future yield potential and actual crop yields by variation in trends (CO2, temperature, precipitation) and variation in the properties of extremes (frequency, amplitude). Both effects contribute to yield gap changes.
Trends are considered in climate change studies by taking the averages of emission scenarios and model predictions. However, extremes, such as, regional droughts and heat waves are not yet considered, although they pose a serious threat to food security. It is therefore important to include climate extremes in the Benchmarking Atlas of future crop production.
The properties of extremes are difficult to extract from climatological time series because extremes are rare and observational time series are often relatively short. To quantify impacts of future changes in extremes on actual and potential yields we propose the following research programme:
- Derive statistical relationships between actual yield and temperature, precipitation, etc.;
- Construct probability density functions (pdfs) that include the properties of extremes based on data, literature, model outcomes, and expert knowledge;
- Adapt a Wageningen crop model to cope with extremes, and incorporate the constructed pdfs to calculate future yield potential and their uncertainty margins;
- Construct uncertainty margins around simulated actual yields.
The results will be compared to a baseline map. We concentrate on maize and winter wheat. Analyses will be done at different spatial scales, from regional to national scales. The emphasis is on Western Europe with additional case studies in Australia, USA, and Brazil, using data that is readily available in AgMIP.