Climate Change Slows Heatwaves, Prolonging Human Misery

A study published in Science Advances on March 29 reveals that climate change is causing heatwaves to decelerate, resulting in prolonged exposure to extreme temperatures, exacerbating the impact on human populations. Unlike previous research that focused on the duration and intensity of heatwaves, this study treated them as distinct weather patterns that move along air currents, similar to storms. Researchers found that heatwaves have been slowing down by an average of 8km per hour per day for every decade between 1979 and 2020.

Senior author Wei Zhang of Utah State University highlighted the significance of slower-moving heatwaves, stating that they allow heat to linger in a region for longer periods, posing significant risks to communities. Using three-dimensional grid cells, the researchers defined heatwaves as zones covering a million square kilometers where temperatures exceeded the 95th percentile of historical maximum temperatures. Climate models were employed to analyze the impact of human-induced climate change, which was identified as a dominant factor contributing to the trend.

The study noted an acceleration in heatwave deceleration since 1997, suggesting a combination of anthropogenic factors and weakening upper atmospheric air circulation. Furthermore, the duration of heatwaves increased from an average of eight days to 12 days over the study period. The authors cautioned that if greenhouse gas emissions continue to rise without effective mitigation measures, longer-lasting and slower-moving heatwaves could have devastating impacts on both natural and societal systems. They expressed particular concern for less-developed regions and disadvantaged populations in urban areas with inadequate cooling infrastructure.

Assistant Professor Zhang emphasized the urgent need for mitigation efforts and investment in green infrastructure to address the disproportionate impacts of heatwaves on vulnerable communities.