New research this week highlights one of the frightening effects climate change is already having on our health: creating bursts of weather extreme enough to kill us. The study estimates that deaths linked to extreme heat and cold have climbed over the past few decades and are likely to only increase in the years to come. In 2019, they estimate that more than 1 million people died as a result of unsafe temperatures.
The study is one of several papers published this week in the Lancet as part of its series examining the connection between heat and human health.
Researchers from the University of Washington looked at mortality data from eight countries stretching back decades—data sourced from the Global Burden of Disease study, a long-running project that tries to estimate the annual toll of major medical conditions on our health and longevity. This data was cross-referenced with temperature readings in those areas throughout the year. The researchers then estimated how often extreme heat or cold contributed to 17 causes of death that are thought to be linked to extreme weather, based on previous research. These causes included heart attack, chronic lung disease, diabetes, and even homicides. Finally, they extrapolated their modeling to the rest of the world to come up with a global estimate.
Between 1980 and 2016, the group estimated that deaths linked to heat rose by 74% worldwide, while deaths linked to extreme cold rose by 31% from 1990 to 2016. In 2019, based on their modeling, they further estimated that there were 1.7 million deaths linked to extreme weather. Broken down, about 1.3 million of these deaths were tied to the cold, and more than 300,000 to the heat. Despite this disparity, extreme heat in already hot areas far surpassed the average burden of cold.
The authors say theirs is the first estimate of its kind to gauge the deadliness of extreme weather across the world. They caution that their modeling does depend on many assumptions, so the figures may not be exact. But they also argue that their numbers are probably conservative.
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In the U.S., the Centers for Disease Control and Prevention estimates there are about 600 heat-related deaths annually (that is, deaths officially linked to heat from death certificates, which are then collected by CDC). Yet other research has suggested that the death toll may be twice that. Just this past June alone, more than 500 people are estimated to have died due to the heat wave that struck the Pacific Northwest areas of the U.S. and Canada in late June. Multnomah County medical officials declared the heat wave a “mass casualty event,” some more often invoked for mass shootings than weather. The heat wave was made 150 times more likely due to climate change. Since then, similarly brutal heat waves have occurred across North America.
The increase over time seen in the new study also offers a worrying portent of what’s to come as the climate continues to get warmer, setting off more intense periods of extreme weather, especially heat waves in the hottest places of the world.
“Our analysis finds that the harmful effects of extreme heat can far exceed those caused by cold in places where it is already hot, such as Southern Asia, the Middle East and many parts of Africa,” study co-author Dr. Katrin Burkhart, a researcher with the Institute of Health Metrics and Evaluation at the University of Washington, told CNN. “This is very concerning, particularly given that the risk of exposure to high temperatures appears to have been increasing steadily for decades.”
The findings come fresh off the tails of the latest Intergovernmental Panel on Climate Change report this month, which painted a sobering future ahead for humanity. Without drastic efforts taken to curb carbon dioxide and other greenhouse emissions now, the impacts of climate change will exponentially worsen in the next few decades. These impacts will undoubtedly include many more killed by the ravages of extreme weather, particularly extreme heat.
Grim as that outlook is, there is still time to change our path, and every single ton of carbon pollution will prevent some amount of harm and death. Even with limiting emissions, though, some worse climate impacts are inevitable. The scientists assembled by the Lancet this week outlined steps countries can take to blunt the impact of extreme heat. They run from providing battery-powered fans to residents most at risk from heat-related deaths to designing better infrastructure in our cities to cut down on heat exposure, like readily available shade.