A study examines the effects of climate change on heat stress. Nations supporting the Paris Agreement, the outcome of the 2015 Paris Climate Conference, pledged to limit global warming to below 2°C above preindustrial levels, but the frequency of extreme heat events is expected to continue rising as the 2°C limit is approached. To examine the extent to which the Paris goals may help avoid human heat stress, Tom Matthews and colleagues used an ensemble of climate models and assessed how global temperature change affects heat stress projections. The models confirm previous reports that global mean air temperature is nonlinearly related to heat stress. The study predicts that the amount of land surface area exposed to dangerous heat stress is likely to rise and that the frequency of dangerous heat stress values will likely increase in areas already experiencing heat stress. The authors estimate that with 2°C of warming above preindustrial levels Karachi, Pakistan and Kolkata, India might face annual conditions similar to the deadly heatwaves that gripped those regions in 2015. Analysis of 44 of the 101 most populous megacities revealed that the number of megacities experiencing heat stress doubled with 1.5°C of warming, potentially exposing more than 350 million additional people to heat stress by 2050 under a midrange population growth scenario. According to the authors, adaptations to extreme heat, alongside climate change mitigation targets, may be required to protect urban populations vulnerable to heat stress. - Read at PNAS
Article #16-17526: “Communicating the deadly consequences of global warming for human heat stress,” by Tom K.R. Matthews, Robert Wilby, and Conor Murphy.