Towards the development of a heat-health early warning system for South Africa

Abstract

TPS 664: Climate change: temperature effects 2, Exhibition Hall, Ground floor, August 27, 2019, 3:00 PM - 4:30 PM Climate change has been associated with changes in temperature extremes globally. This includes a higher frequency and severity of hot days and heatwaves. Exposure to high temperatures poses a significant public health concern as people of all ages are at risk of the negative health effects of exposure to heat. These include cramps, fainting, heat exhaustion, heat stroke, dehydration, disease exacerbation and death in some cases. Heat alerts in South Africa are currently based on defined temperature-fixed threshold values for large towns and cities. However, heat-health early warning systems (HEWS) should be based on thresholds that are related to heat-related health outcomes. Therefore, this study aims to contribute towards the development of an evidence-based HEWS for South Africa that incorporates high temperatures and mortality. Mortality data were provided by Statistics South Africa for 1997 to 2013. Daily minimum, maximum and mean temperatures were obtained from the National Oceanographic and Atmospheric Administration and South Africa’s Agricultural Research Council. The joint CCl/CLIVAR/JCOMM Expert Team on Climate Change Detection and Indices has developed a core set of 27 temperature extreme indices that is widely used as a tool to assess and monitor changes in weather and climate extremes. RClimDex developed by Zhang and Feng at the Climate Research Branch of Meteorological Service of Canada was used to calculate monthly extreme temperature indices for each district (n = 52). The random forest (RF) algorithm for regression was used to assess the effect of the calculated indices on mortality by identifying the most significant index in each district using the variable importance score. Sensitivity analysis included tuning parameters within RF. Diurnal temperature range was the index most frequently selected as a top variable. Results are discussed in light of recommendations for HEWS for South Africa with relevance to other southern African and developing countries.