The world is projected to witness an alarming increase in superhot days, potentially adding nearly two months of these dangerously high temperatures each year by the end of the century. A recent study highlights that poorer small nations are likely to be disproportionately affected compared to larger carbon-emitting countries.
The study, conducted by climate scientists from World Weather Attribution and Climate Central, underscores the significance of the efforts made to reduce emissions of heat-trapping gases since the implementation of the Paris climate agreement ten years ago. This international accord has effectively mitigated the expected increase of superhot days; without these efforts, the planet would be on track to experience an additional 114 days of extreme heat each year.
Using computer simulations, the research analyzed the occurrences of superhot days across more than 200 countries, comparing data from 2015 to current figures, and projecting future scenarios. The first scenario assumes that nations meet their emissions-reducing commitments, resulting in a global temperature rise of 2.6 degrees Celsius (4.7 degrees Fahrenheit) above preindustrial levels. This could lead to 57 additional superhot days. The alternative scenario predicts a disastrous 4 degrees Celsius (7.2 degrees Fahrenheit) increase, doubling the number of extra hot days under the current trajectory.
Kristina Dahl, Vice President for Science at Climate Central and a co-author of the report, highlights the grim reality of climate change, stating, "There will be pain and suffering because of climate change." Yet, she points out an encouraging aspect: the difference in impacts due to the reduction of potential warming from 4 degrees Celsius to 2.6 degrees Celsius within the past decade.
The study defines superhot days as those with temperatures exceeding 90% of comparable dates between 1991 and 2020. Since 2015, the global average has already seen an increase of 11 superhot days. The health impacts are significant; as Dahl noted, "That heat sends people to the emergency room. Heat kills people." While the report does not specify the exact number of individuals at risk from these additional hot days, Friederike Otto from Imperial College London emphasized that "it will definitely be tens of thousands or millions, not less," given the existing fatalities during heat waves each year.
Examining past heat waves, the 2023 heatwave in Southern Europe is now 70% more likely and 0.6 degrees Celsius (1.1 degrees Fahrenheit) warmer than it would have been a decade ago. Projections suggest that if climate actions do not accelerate, similar heat events could be up to 3 degrees Celsius (5.4 degrees Fahrenheit) hotter by the century's end.
The inequality in heat distribution becomes evident when analyzing the expected increases in superhot days across nations. Countries that are projected to experience the most significant rises are often small and island nations, such as the Solomon Islands, Samoa, Panama, and Indonesia. For instance, Panama is anticipated to face 149 extra superhot days. Collectively, these top ten nations have contributed a mere 1% to global heat-trapping gas emissions but will endure nearly 13% of the increased superhot days.
In contrast, significant carbon-emitting nations like the United States, China, and India are predicted to see only 23 to 30 additional superhot days, despite being responsible for 42% of atmospheric carbon dioxide. This stark contrast exemplifies the disproportionate burden of climate change on developing nations, as acknowledged by University of Victoria climate scientist Andrew Weaver, who noted that global warming exacerbates existing inequalities and hinders development.
Within the United States, Hawaii and Florida are expected to experience the largest increases in superhot days by century's end, while Idaho will see the smallest rise. While it is a relief that the world is no longer on the 4-degree warming trajectory, Johan Rockstrom of the Potsdam Climate Institute warns that the current path still entails catastrophic consequences for billions around the globe.
