Science-based information for adaptation to climate change in rainfed agriculture

Globally about 60% of our food is produced under rainfed agriculture (RFA), i.e. without significant irrigation infrastructure. In some regions of the world, such as sub-Saharan Africa, Southeast Asia, etc., RFA can cover more than 90% of food production. At the same time, RFA is extremely vulnerable to climate variability and change, through changes in rainfall (timing and intensity) and air temperature (warming and higher evaporative demand). This significantly challenges the future of food security and the livelihoods of farmers in RFA regions, particularly in small-holder subsistence systems. It is therefore a high priority to be able to provide stakeholders in such RFA systems with state-of-the-art information about their vulnerabilities today and in the future, so they can prepare and adapt.

Here we provide an example of such science-based information on the key aspects (climatic, hydrological, agroecological) of the functioning of RFA systems in Ethiopia, combining publicly available gridded climate, soil, land use, and crop data with agrohydrological models and data analytics. We present three main results of such analyses: (a) We show how the temporal characteristics of rainfall can be quantified, particularly the onset of the rainy season and the seasonal distribution of rainfall, which fundamentally determine the growing season water availability, and we show how delays in the rainy season led to measurable crop yield losses. (b) We show how water-limited crop yields (crop yield gaps) within the growing season can be estimated by an agrohydrological modelling framework under present and future climates, and we illustrate where rainfall or temperature changes dominate the response. (c) We show how the potential changes in cropland suitability given by a combination of climatic and soil properties for staple crops can be quantified, allowing good spatial predictions of where/which crops can grow today and in the future.

Ultimately, this work shows that climate change is likely to negatively affect future water availability and crop yields, especially in dry areas across the RFA region of Ethiopia. The anticipated impacts on cropland suitability are potentially severe, leading to elevation-related shifts and an overall reduction in suitable cropland areas for major cereal crops such as maize, teff, sorghum, and wheat. Our methods can be replicated in other RFA regions globally and we argue that such analyses can be a critical source of science-based information needed for risk management and for developing long-term climate adaptation plans for climate resilient crop production.