Drought and heat-stress mortality risks: Assessing the role of climate change, socioeconomic vulnerabilities, and population growth

Drought risk refers to the potential losses imposed by a drought event, and it is generally characterized as a function of vulnerability, hazard, and exposure. Here, we assess drought risk at a national level across Africa by considering climate change, population growth, and socioeconomic vulnerabilities. Drought vulnerability is quantified using a rigorous multi-dimensional framework based on 28 factors from six different sectors of economy, energy and infrastructure, health, land use, society, and water resources. Various analyses are conducted to assess the reliability and accuracy of the proposed drought vulnerability index (DVI). A multi-model and multi-scenario framework is employed to quantify drought hazard using a multitude of regional climate models. Drought risk is then assessed for 2 climate emission pathways (RCP4.5 and RCP8.5), 3 population scenarios, and 3 future vulnerability scenarios in each country during 2010-2100. Drought risk ratio is calculated for each scenario, and the role of each component (i.e. hazard, vulnerability, and exposure) is identified, and the associated uncertainties are also characterized. Results show that drought risk is expected to increase in future across Africa with varied rates for different models and scenarios. Although northern African countries indicate aggravating drought hazard, drought risk ratio is found to be highest in central African countries as a consequent of unprecedented vulnerability and population rise in the region. Results indicate that controlling the population growth is imperative for mitigating drought risk since it improves socioeconomic vulnerability and reduces potential exposure to drought. Meanwhile, climate change will considerably exacerbate drought and heat-stress hazards. Our findings show that global warming will escalate heat-stress mortality risk across Central Africa to unprecedented levels. It is revealed that unfortunately, the poorest countries (that have least contribution to climate change) are expected to be most impacted, and they will experience markedly higher risk ratios compared to the wealthier nations.