Climate Matters
Warming Across Generations
New Climate Central analysis reflects the theme of tomorrow’s World Meteorological Day—by comparing the lifetime warming experienced across generations, depending on how quickly we cut carbon pollution.
Climate Matters•September 3, 2025
Childhood Heat Risk is Rising
KEY FACTS
New analysis shows that, because of climate change, younger people today are experiencing far more extreme heat during childhood than previous generations did.
Extreme heat can be dangerous for everyone, but it can be especially harmful for the health, well-being, and development of kids.
On average across 247 major U.S. cities, a Generation Z child experienced 2x more extremely hot days because of climate change than a millennial child — and 4x more than a Generation X child.
Climate Central’s new interactive tool lets users explore how climate change has influenced the extreme heat they’ve experienced over their lifetime.
More heat brings more health risks — especially for kids
Hot days are more than uncomfortable — they can affect our health and well-being. And kids are among the most vulnerable to these risks. Excessive heat during childhood can affect kids’ health, development, mood, sleep, and even their ability to concentrate and learn.
Climate Central’s fact sheet, Climate Change & Children’s Health: Extreme Heat, details how warming trends are worsening heat-related health risks for children.
Summers have warmed across the U.S., and extremely hot days now happen more often because of human-caused climate change.
This means younger people today are experiencing more extremely hot days during their childhood compared to previous generations.
Analyzing how carbon pollution affects childhood heat exposure
Climate Central analyzed daily maximum temperatures between 1970-2024 in 247 U.S. cities. Using our Climate Shift Index data, we counted the days of extreme heat added by climate change each year.
We counted the total number of extremely hot days added by climate change during representative childhoods across three generations: Generation X (represented by 1971-1988), millennial (1989-2006), and Generation Z (2007-2024).
Younger generations face more extreme heat because of climate change
On average across 247 major U.S. cities, a Gen Z child experienced 2x more extremely hot days because of climate change than a millennial child — and 4x more than a Gen X child.
On average, millennials also saw twice as many days of extreme heat during their childhood because of carbon pollution on average compared to Gen X kids.
In 128 cities, Gen Z kids experienced at least 180 more days of climate change-fueled extreme heat than Gen X kids experienced during childhood. That’s equivalent to at least six extra months of extreme heat added by climate change during a Gen Z childhood.
And in 27 cities, a Gen Z childhood included a total of 365 or more extremely hot days that wouldn't have happened in a world without carbon pollution.
In many places, the intergenerational differences in childhood extreme heat is striking. For example:
In Honolulu, Hawaii, climate change added 197 days of extreme heat for a Gen X kid. Some three decades later, climate change added 787 days of extreme heat for a Gen Z kid in Honolulu. That’s a four-fold increase between the generations.
In Bismarck, North Dakota, climate change didn’t add any extremely hot days for a Gen X kid. But for a Gen Z kid living there, climate change added 161 days of extreme heat during their childhood.
How has climate change shaped your lifetime of heat?
Climate Central’s new interactive tool lets users explore how climate change has influenced the extreme heat they’ve experienced over their lifetime. Use the tool to compare your experience to people in other locations and generations.
Future generations face rising risks
With continued warming, younger generations will face accelerating change and intensifying risks — particularly from heat.
Ultimately, cutting carbon pollution would set younger generations on a path toward a safer future. Even if we do manage to limit global warming to 1.5°C above pre-industrial levels, about half of all people born in 2020 will still experience unprecedented lifetime exposure to heatwaves.
LOCAL STORY ANGLES
How many more climate extremes could you face across your lifetime?
Explore My Climate Future, an interactive online tool based on data from a 2021 study that analyzed intergenerational exposure to climate extremes globally. This tool can be used to estimate how many more climate extremes (including wildfires, droughts, tropical cyclones, and heatwaves) you could experience over your lifetime than you would without climate change.
How do views on climate change differ across generations in the U.S.?
According to survey data from Yale University and George Mason University, younger generations are more likely to believe the scientific consensus that climate change is happening and is human-caused. Use interactive climate opinion maps to explore public climate opinions in your state, county, or city — including perceptions of climate-related harm to future generations. Findings from a Pew Research Center survey in 2021 also found that millennials and Gen Z in the U.S. tend to be more active than older generations in addressing climate change.
FIND EXPERTS
Submit a request to SciLine from the American Association for the Advancement of Science or to the Climate Data Concierge from Columbia University. These free services rapidly connect journalists to relevant scientific experts.
Browse maps of climate experts and services at regional NOAA, USDA, and Department of the Interior offices.
Explore databases such as 500 Women Scientists, BIPOC Climate and Energy Justice PhDs, and Diverse Sources to find and amplify diverse expert voices.
Reach out to your State Climate Office or the nearest Land-Grant University to connect with scientists, educators, and extension staff in your local area.
METHODOLOGY
Climate Central analyzed daily temperatures (using ERA5 reanalysis temperature data, available at a resolution of 0.25°, or 31 km) from 1970-2024 in 247 U.S. cities.
Extremely hot days are defined as days when maximum temperatures were hotter than 90% of temperatures observed at a given location, compared to 1991-2020 (also referred to as temperatures above the 90th percentile).
Using Climate Central’s Climate Shift Index system, we calculated the number of extremely hot days that would have occurred in a world without human-caused climate change (i.e., a counterfactual scenario) and compared that to the total number observed each year. This allowed us to count how many days with extreme heat were added by climate change annually.
We counted extremely hot days due to human-caused climate change during representative childhoods across three generations: Generation X (1971-1988), millennial (1989-2006), and Generation Z (2007-2024). These three 18-year periods represent the childhood (first 17 years of life) of someone born in the starting year.