Increasing Heat-Stress Inequality in a Warming Climate

thermometer on orange surface

Observed heatwave trends have been on the rise in the last four decades according to a research article published in January, 2022. The study titled, “Increasing Heat-Stress Inequality In A Warming Climate”, projects further intensification of extreme heat events in the future. Excess heat events like heatwaves are a symptom of increasing temperature averages across many regions of the globe. High temperatures are an immediate threat to human wellbeing as they may contribute to crop failure, worsened wildfires and or heat-related deaths, such as heat exhaustion and heat stroke.

How Is Heat Stress Related to Climate Change?

Researchers of the 2022 study assert that their “findings demonstrate continued increases in heatwave exposure inequality because of delays in adaptation capacity in the developing world, compounded by a higher emergence of warming in low-latitude areas where most of the low-income countries occur”. Societies in the lowest-income regions are projected to have greater difficulties adapting to the challenges posed by a warming climate.

How Does Climate Change Affect Heat Waves?

This study used heatwave data from the years 1980-2019, and modeled future temperatures for 2030-end of century. Heatwaves here are defined as “an event during which daily mean temperature exceeded the 97th percentile of local annual mean daily temperature in a reference period for at least three consecutive days”. Authors of the study claim that they are operating under the assumption that vulnerability to heatwave-related risks and degrees of suffering are determined by economic development status.

Thus, researchers split all regions of the world into four socioeconomic classes for income: lowest, lower-middle, upper-middle, and highest, (based on population-weighted per-capita gross domestic product in 2015). They were then able to create a spectrum for economic adaptive capacities. Adaptation capacities include cooling systems, electricity, early detection and warning systems and infrastructure.

As reported in the study, a 60% global increase in the total number of heatwave days were recorded over the past 40 years. Average yearly heatwave seasons were 75% longer during the 2010 years compared to those in the 1980s. Also, “the maximum decadal amplitude of shock heatwave was between 2.16 (Europe) and 3.27 (North America) °C higher in the 2010s as compared to the 1980s”. Although heatwaves intensified across all socioeconomic classes, the “low-income region” observed the rate of increase in heatwave season length yearly.

Which Place Is Most Affected by Climate Change?

In the 2010s, the “high-income region” experienced 30% fewer heatwave days. Sensitivity to heat waves is significantly determined by a society’s adaptation efforts. Regions with relatively low incomes will face greater challenges and vulnerability to heatwaves due to their lack of access to resources which enable adaptation across sectors. Inferior adaptation capacities may hinder or delay institutional heatwaves responses to heatwaves, making societies with lower scoring GDPs more susceptible to the impacts of rising temperature averages and excess heat.

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