Heat Waves Could Kill Thousands of People in U.S. Cities if Climate Goals Aren’t Met

A new study calculates that as temperatures increase, up to 5,800 people will die in New York and 2,400 in L.A. during the hottest years

Heat Wave New York
People enjoy a hot afternoon at the Astoria Pool in the borough of Queens on August 17, 2015, in New York City. Spencer Platt/Getty Images

When faced with extreme weather incidents, whether its flooding, hurricanes, wildfires or severe thunderstorms, it can be challenging to pinpoint the human toll as a result of global climate change. A new study in the journal Science Advances, however, attempts to put some hard numbers on the crisis by extrapolating out how many residents in U.S. cities would die from heat-related causes should temperatures continue to increase.

If average temperatures rise by 3 degrees Celsius, or 5.4 degrees Fahrenheit, above preindustrial temperatures, during any one particularly hot year, New York City can expect 5,800 people to die from heat. Los Angeles will see 2,500 die and Miami will see 2,300. Even San Francisco, of where it's been said "The coldest winter I ever spent was a summer in San Francisco," could see 328 heat-related deaths. But the research also shows that if action is taken to limit warming, thousands of lives in cities across the U.S. could be saved.

For the study, researchers looked at temperature and heat mortality data from 15 U.S. cities between 1987 and 2000. Using computer models, they simulated various warming scenarios figuring out how many Americans would die in each city based on global average temperature increases of 1.5, 2 and 3 degrees Celsius during a year that was the warmest in the past 30 years. (We're already more than a third of the way there, having passed 1 degree Celsius over preindustrial temperatures in 2015.) They found that almost all cities involved would see deaths rise, with the totals depending on their regional climate, population and other factors.

But according to the models, if warming was limited to 1.5 degrees Celsius, the goal set forth in the Paris Climate Agreement, it would save upwards of 2,720 lives during years experiencing extreme heat.

“Reducing emissions would lead to a smaller increase in heat-related deaths, assuming no additional actions to adapt to higher temperatures,” co-author Kristie Ebi of the University of Washington tells Oliver Milman at The Guardian. “Climate change, driven by greenhouse gas emissions, is affecting our health, our economy and our ecosystems. This study adds to the body of evidence of the harms that could come without rapid and significant reductions in our greenhouse gas emissions.”

In the next decade, the world could soon start to occasionally bump above 1.5 degrees Celsius of warming and is on course to exceed 3 degrees Celsius by 2100.

“At the path we are on, toward 3 degrees Celsius warming, we get into temperatures that people have not previously experienced,” co-author Peter Frumhoff, chief climate scientist at the Union of Concerned Scientists tells Bob Berwyn at Inside Climate News. “The core point is, across these cities, thousands of deaths can be avoided by keeping temperatures within the Paris target.”

While most predictions about the effects of climate change have been fairly general, the authors say in a press release that calculating actual death tolls in specific cities changes the narrative.

“We are no longer counting the impact of climate in change in terms of degrees of global warming, but rather in terms of number of lives lost,” co-lead author Dann Mitchell from University of Bristol says. “Our study brings together a wide range of physical and social complexities to show just how human lives could be impacted if we do not cut carbon emissions.”

Berwyn reports that calculating potential heat-related mortality for other cities around the world is difficult since reliable health data is unavailable. But a recent study looking at Europe found that if temperatures increase by 2 degrees Celsius, there will be 132,000 additional deaths on the continent.

While thousands of heat-related deaths in American cities is attention grabbing, they pale in comparison to the impacts that may already be occurring due to climate change. A report from the Lancet released late last year found that in 2017 alone 153 billion work hours were lost due to extreme heat and hundreds of millions of vulnerable people experienced heat waves. Changes in heat and rainfall have caused diseases transmitted by mosquitoes or water to become 10 percent more infectious than they were in 1950. The same factors are damaging crops and reducing their overall nutrition, leading to the three straight years of rising global hunger after decades of improvements. All of those problems are expected to increase along with temperatures.

The impacts on health aren’t all caused by heat and weather disruption either. The World Health Organziation released a report last year showing fossil fuel pollution currently causes more than a million preventable deaths annually and contributes to countless cases of asthma, lung disease, heart disease and stroke. According to the study, the improved health benefits of moving to cleaner energy would double the costs of cutting those emissions.

Berwyn reports that deaths from extreme heat, especially in the United States, are preventable, since heat waves can be forecast and mitigated. Many cities already have heat action plans, including projects like providing air conditioning for seniors and other vulnerable populations. But Julie Arrighi, a climate expert with the International Red Cross Red Crescent Climate Centre says many of those plans need to be scaled up to meet predicted future temperatures. And in the Global South, which will bear the brunt of the heat, urgent action is needed to help city dwellers prepare for a future full of record breaking temperatures.

Get the latest stories in your inbox every weekday.