Oct 27, 2022 - Energy & Environment

Climate change raised temperatures for 7.6 billion

Illustration of the earth as a steaming teakettle

Illustration: Sarah Grillo/Axios

Human-caused climate change made everyday temperatures warmer for 7.6 billion people last year, according to a new analysis by research and news nonprofit Climate Central.

The big picture: Impacts of the warming planet on daily temperatures are being felt by roughly 96% of the world's population, with the strongest influences in cities across the Global South.

Context: Climate Central researchers measured the influence of climate change on daily average temperatures for 1,021 major global cities between Oct. 1, 2021 and Sept. 30, 2022.

  • They used the organization's newly expanded "Climate Shift Index," which quantifies how much climate change has altered the likelihood of daily average temperatures at locations worldwide.

What they found: On any given day over the last year, at least 200 million people experienced temperatures that climate change made more likely, the analysis shows.

  • Cities in small island developing states — a group of island countries in the Caribbean, Pacific, Atlantic, Indian Ocean and South China Sea — had the highest average CSI scores, meaning climate change has had the clearest influence on their day-to-day temperatures over the last year.
  • When considering total population size, human exposure to daily temperatures altered by climate change was at its highest in the urban environments of Lagos, Nigeria, Mexico City, Mexico and Singapore.

Between the lines: The places experiencing the biggest impacts of climate change on daily temperatures are in developing countries that have contributed little to global warming.

How it works: The CSI of a place is calculated by incorporating peer-reviewed methods and weather data to estimate how often the temperature at that location is likely to occur in the current climate, as well as the likelihood in a world without climate change. (The analysis itself wasn't peer-reviewed.)

  • "We do a really direct comparison of a world with and without extra CO2," Andrew Pershing, director of climate science at Climate Central, told Axios.

What they're saying: Stephanie Herring, a climate attribution scientist at the National Oceanic and Atmospheric Administration who wasn't involved with the project, told Axios in an email that the CSI tool is unique because it focuses on the impact of climate change on daily temperatures, while most attribution research looks at extremes.

  • The tool shows that "climate change isn't just showing up in the most extreme, one in a hundred year heat events," Herring wrote. "We can see the impact in our everyday lives."

Our thought bubble: With COP27 just around the corner — and loss and damage payments for developing nations likely on the agenda — these findings further magnify the unequal impacts of climate change.

  • "Look at places like the equatorial regions in Africa, the equatorial regions in South America, the small island nations," Pershing told Axios. "They're just living in a climate that is radically different than what it would be if we didn't have extra CO2 in the atmosphere."
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