UW News

June 5, 2019

Urgent action on climate change will prevent heat-related deaths in major U.S. cities

HeatMortalityMap_PerCityNew study in Science Advances finds meeting Paris Agreement goals
could save thousands of lives

The planet will warm by about 3 degrees Celsius (5.4 degrees Fahrenheit) above pre-industrial levels by the end of the century if the U.S. and other nations meet only their current commitments under the Paris climate agreement to reduce emissions of heat-trapping gases. According to a paper by U.S. and U.K. scientists published in Science Advances today, accelerating ambition to reduce global warming emissions to meet the Paris Agreement’s goal of limiting temperature rise to well below 2 degrees Celsius could prevent thousands of extreme heat-related deaths in cities across the U.S.

“All heat-related deaths are potentially preventable,” said UW Professor Kristie Ebi.

This first-of-its-kind study — led by Eunice Lo of the University of Bristol in the U.K. and co-authored by a team of researchers, including Kristie L. Ebi, professor and researcher at the University of Washington’s School of Public Health, and Peter Frumhoff, director of science and policy and chief climate scientist at the Union of Concerned Scientists — examines the impact on mortality rates of projected high temperatures associated with extreme heat expected to occur once every 30 years on average in 15 U.S. cities: Atlanta, Boston, Chicago, Dallas, Detroit, Houston, Los Angeles, Miami, New York, Philadelphia, Phoenix, San Francisco, Seattle, St. Louis and Washington, D.C.

“Climate change is not only affecting faraway places but also the United States,” said Lo. “As temperatures rise, exposure of major U.S. cities to extreme heat will increase and more heat-related deaths will occur. The United States has emitted the largest amount of carbon dioxide in the world since the 18th century. Immediate and drastic emissions cuts are key to preventing large increases in heat-related deaths in the country.”

Climate change is already increasing the severity of extreme heat. If global temperature increases reach 3 degrees Celsius, these cities would experience more severe heat waves than if temperature rise is limited to 1.5 or 2 degrees Celsius. The study used the different high temperatures projected under three warming scenarios for 1-in-30-year events in each city.

At 3 degrees Celsius, there would be between about 330 and 5,800 heat-related deaths per city for each 1-in-30-year event, with cities like Chicago, Los Angeles, Miami, New York and Philadelphia facing the highest number of fatalities. Limiting global temperature rise to 2 degrees Celsius avoids between about 70 and 1,980 extreme heat-related deaths per city. Even more heat related deaths — between about 110 and 2,720 — can be avoided by achieving the 1.5 degrees Celsius threshold.

To view a spreadsheet highlighting the main findings for each U.S. city, click here.

Click here for a graphic displaying the overall findings per city or click here for the per capita findings graphic.

“This study shows that taking urgent action to reduce carbon pollution will save lives in cities across the United States,” said Frumhoff. “The government also has an obligation to help communities prepare for life in a world that’s heating up. This could include making air conditioning more available especially to those with low or fixed incomes, strengthening our health care system, and increasing awareness of heat-related health risks.”

“All heat-related deaths are potentially preventable,” said Ebi. “We need urgent investment in heat wave early warning and response systems and other options to protect the most vulnerable as temperatures continue to rise. Older adults, children and outdoor workers are among those populations particularly susceptible to higher temperatures. In the long term, urban planning must prioritize design changes that decrease urban heat islands and ensure our infrastructure is prepared for unprecedented temperatures.”

The numbers of avoided heat-related deaths in the analysis may be a conservative estimate, as they rely on current population data. Therefore, they cannot account for an aging population, increases in urbanization, exacerbation of the urban heat island effect, or other demographic factors that could change and contribute to added heat vulnerability.


For more information, contact Ebi at krisebi@uw.edu or 206-543-8440.