Heat-related mortality attributable to human-induced climate change in Brazil’s low-income population.

Climate detection and attribution is essential for demonstrating the link between climate-related impacts, such as heat-related mortality, and human-induced heating. To date, limited studies have directly attributed the health impact of climate change to anthropogenic actions, and most of the existing studies are focused on regions in the Global North. Here we aim to quantify the heat-related mortality attributable to anthropogenic climate change in a low-income population in Brazil over the period 2000-2018.

We explore heat-related mortality in a low-income population in Brazil using the 100 million Brazilian cohort. This cohort accounts for approximately 60% of the total Brazilian population and contains individual-level information on people eligible for social-assistance programs. We first establish a heat-mortality relationship by generating relative risk curves using a Distributed Lag Non-linear Model (DLNM). We then use output from the Coupled Model Intercomparison Project phase 6 (CMIP6) Detection and Attribution (DAMIP) model ensemble to quantify heat-related mortality in factual and counterfactual climates.

We find that approximately 85,700 heat-related deaths can be directly attributed to human induced climate change over the period 2000-2018. This means that 4,500 heat-related deaths per year would not have occurred if human emissions of greenhouse gases had not warmed the climate. This amount of warming is estimated to be 0.92°C relative to a 1961-1990 baseline. We also estimate the attributable fraction of all-cause mortality in this low-income population in Brazil to be 2.45%.

Our findings demonstrate the urgent need to reduce greenhouse gas emissions and limit global heating to avoid future loss of life. They also highlight the ongoing inequality of climate change impacts and provide detailed understanding of the heat-related mortality burden faced by vulnerable populations in Brazil.