Impact

Climate Impact Lab: How Much Hotter Is Your Hometown Than When You Were Born?

Our state-of-the-art analysis of historical climate data and localized climate projections powers a New York Times interactive that helps localize global warming.

As the world warms because of human-induced climate change, most of us can expect to see more days when temperatures hit 90 degrees Fahrenheit (32 degrees Celsius) or higher. The New York Times published an interactive based on new analysis by the Climate Impact Lab, a consortium of climate scientists, economists and data engineers at Rhodium Group, University of California Berkeley, University of Chicago and Rutgers University.

This project shows how global warming caused by rising greenhouse gas (GHG) concentrations are making 90-degrees Fahrenheit days more frequent around the globe. It presents users with a localized perspective, anchored to weather station data from their hometown, of changes in global temperatures since their birth and over the rest of their lifetimes.

Exploring localized data for areas around the globe shows many places are likely to feel this extra heat even if countries take action to lower their emissions by the end of the century. If countries continue emitting at historically high rates, the future could look even hotter.

How different cities and regions experience an increase in 90-degree days depends in part on how well adapted to heat they already are, our climate scientist Kelly McCusker, told the New York Times.

In North America, more frequent hot days will be less disruptive in Phoenix, where residents are already used to blistering temperatures, than in Montreal, where an estimated 40 percent of households don’t have air conditioning.

But how much hotter it gets matters, too. In Phoenix, more 90-degree days will most likely also mean more days in the high 90sand above. (This summer, temperatures in the city soared to 115 degrees.) In Montreal, such scorching heat will most likely remain rare, even as days in the low 90s become more common.

Worldwide, high temperatures have been found to increase the risk of illness and death, especially among older people, infants and people with chronic medical conditions. Lower-income populations, which more often lack access to air conditioning and other adaptive technologies, are also more likely to suffer the impacts of extreme heat. In America, so are people of color.

Outdoor workers are particularly vulnerable to more frequent hot days, but excessive heat has consequences for indoor factory workers, too, especially in developing countries, where workspaces are less likely to be cooled.

An increase in 90-degree days will also be more painful in humid regions than in dry ones.

“A very important factor for how humans experience heat is how humid it is,” Dr. McCusker said. “If it’s also humid, humans can’t physiologically evaporate sweat as easily, and we can’t cool down our bodies effectively.”

Read the full story here and learn more about our methodology on the Climate Impact Lab site.