Climate Change to Worsen Ground-Level Ozone Spikes by 2050, Study Finds

A new study reveals that climate change is likely to exacerbate ground-level ozone spikes by 2050, potentially causing numerous areas in the United States to fall out of compliance with air quality standards and increasing public health risks.

Ozone, a reactive gas comprising three oxygen atoms, can be naturally occurring but often forms at ground level through interactions between volatile organic compounds (VOCs) and nitrogen oxides (NOx), both of which are air pollutants. Ground-level ozone is a significant concern because it can lead to various health issues, including decreased lung function and airway inflammation, contributing to hundreds of thousands of deaths annually.

"Climate change affects ozone formation through a complex set of factors, but warmer temperatures are correlated with increases to ozone in polluted areas," says James East, first author of a paper on the study and a former Ph.D. student at North Carolina State University who is now a researcher at Harvard University.

He added:

"That means areas that already have higher levels of air pollution of VOCs and NOx will likely see increases in ozone as average temperatures go up. What's more, climate change is expected to increase naturally occurring VOC emissions in some parts of the U.S., such as the Southeast, exacerbating the challenge."

The study specifically examined how frequently ozone levels would surpass air quality standards, the extent to which they would exceed these standards, and how these patterns might change by 2050. The findings are presented as a range due to uncertainties about the climate's sensitivity to greenhouse gas concentrations.

In the best-case scenario, where the climate shows low sensitivity to carbon dioxide, the study finds that high ozone measurements would increase by less than 0.3 parts per billion (ppb) on average. While these measurements might still be below current air quality standards in many locations, variability in ozone levels would increase, leading to more days with exceptionally high ozone spikes that breach the standards.

Conversely, in the worst-case scenario, where the climate is highly sensitive to carbon dioxide, high ozone measurements would increase by over 2.3 ppb on average. This scenario would result in a significant rise in days when ozone levels exceed air quality standards across many parts of the country.

This research, conducted with support from the Natural Sciences and Engineering Research Council of Canada, was published under the title “Projecting Changes in the Frequency and Magnitude of Ozone Pollution Events Under Uncertain Climate Sensitivity” in Earth’s Future, a peer-reviewed journal that examines “the state of the planet and its inhabitants.”