Identifying Rural African Humid Heat Exposure Hotspots using High-Resolution Observations and 2030/2050 CMIP6-based projections

Increasing air temperatures, rapid population growth and limited adaptive capacity pose serious health risks in Africa. The very low number of daily weather observations, however, makes the study of trends and spots very difficult. To help overcome this challenge, the USAID-funded Climate Hazard Center has developed the high-resolution (0.05°) 'Climate Hazards center InfraRed Temperature with Stations (CHIRTS) dataset (Funk et al. 2018; Verdin et al. 2019). As shown in these papers, and in a recent PNAS assessment of global urban heat exposure (Tuholske et al. 2021), CHIRTS does much better than competing products because it incorporates satellite-based temperature observations (similar to the widely used CHIRPS), fairly dense station observations, and a high-resolution climatology. This makes CHIRTS-based Wet Bulb Globe Temperatures (WBGT) well-suited to analyses in the Global South. In urban areas, 1983-2016 heat exposure has already increased by 200%. We build on this study, but focus on rural regions. Many densely populated agriculturally important areas of Africa are humid and hot. Using daily gridded WBGT and population estimates, we explore observed means and trends in the number of days and people-days with extreme WBGT. Special focus is given to agricultural areas with high population and high humid heat exposure. African farmers, most of whom are women, have little choice but to engage in strenuous activity, even in warm weather. We also consider potential impacts on labor productivity, crop production, and per capita grain production. The talk concludes with an analysis of new projections of 2030 and 2050 WBGT and heat exposure. These projections are based on a combination of CHIRTS and 2 IPCC CMIP6 climate change scenarios (SSP245, SSP585). The observations and projections indicate large increases in risk, but these risks are focused in certain locations and seasons. Identifying these hotspots now will help us develop early warning systems for a rapidly-arriving future.