Implications of climate emission scenarios on heat-attributable cardiovascular deaths in west and central sub-Saharan Africa
G Parameswaran, S R Ponnana, T Zhang, N Surya, S K Sirasapalli, J E Dazard, Z Chen, S V Deo, S RajagopalanAbstract
Background
West and Central Sub-Saharan Africa faces intersecting climate-related risks of extreme temperatures, limited regional resilience and constrained societal adaptive capacity. Extreme heat represents a modifiable yet under-recognised cardiovascular disease (CVD) risk factor. Given that this region is home to over 500 million people across diverse climate zones with population growth among the fastest globally, there is an urgent need to quantify the burden of heat-attributable CVD.
Purpose
To quantify current and future heat-attributable CVD deaths across continental West and Central Africa under different climate scenarios.
Methods
We conducted a grid-based analysis across 23 countries at 0.25° resolution (17,334 grid cells). Daily mean temperatures were extracted from ERA5-Land reanalysis (2016-23 baseline) and 5-climate model CMIP6 ensemble for 2040 and 2050 under Shared Socioeconomic Pathway (SSP) 2-4.5 (moderate) and SSP5-8.5 (high) emission scenarios. We assigned Köppen climate zone-specific relative risks (RR) from published exposure-response studies and calculated population-attributable fractions using each grid cell's temperature distribution relative to its temperature of minimum risk. National CVD mortality rates (2016-23) were obtained from Global Burden of Disease 2023 and spatially disaggregated to grid cells using WorldPop 2023 population. Grid-level SSP population growth factors were applied to project future populations, with CVD mortality scaled proportionally. Heat-attributable CVD deaths were estimated and aggregated by country. Monte Carlo simulations (10,000 iterations) propagated uncertainty from RR estimates and mortality data.
Results
At baseline (2016-23), we estimated 12,905 (95% CI: 8,319-18,204) annual heat-attributable CVD deaths—1.9 (1.1-2.7) per 100,000. Sahel countries Guinea (3.1 per 100,000) and Chad (3.0 per 100,000) bore the highest baseline burden (Figure 1). By 2050, deaths increased 294% to 50,809 (7.4 per 100,000) under SSP2-4.5 and 316% to 53,698 (7.8 per 100,000) under SSP5-8.5 (Figure 2). The Central African nations of Equatorial Guinea and Gabon face the highest relative increases under both scenarios (SSP5-8.5: 902% and 865% respectively). Under SSP5-8.5, Cameroon and Ghana had the highest absolute rates at 11.2 and 11.1 per 100,000 respectively.
Conclusions
Heat-attributable CVD mortality in West and Central Africa is projected to nearly quadruple by 2050 even under moderate emissions, with increases substantially exceeding projections for high-income regions. These findings demand urgent public health action including implementation of national heat action plans, climate adaptation strategies, and targeted CVD risk reduction programmes to mitigate this burden and protect vulnerable populations across sub-Saharan Africa.Figure 1:Heat-CVD, West-Central AfricaFigure 2:Heat-CVD, Baseline to 2050