Green Clay Tennis Courts Absorb CO2: A Climate-Friendly Surface?
Green clay tennis courts in the United States are quietly emerging as a potential tool in carbon dioxide removal, according to research published this month in Applied Geochemistry. A study led by researchers at New York University and the University of Washington found that these courts, constructed with a basalt-based material, actively absorb carbon dioxide from the atmosphere through a process called enhanced rock weathering.
The research team, comprised of Jonathan Lambert, an earth scientist and visiting assistant professor at NYU’s Gallatin School of Individualized Study, and Frank J. Pavia, an assistant professor at the University of Washington, analyzed data from 17,178 green clay courts across the country. They calculated carbon sequestration rates by factoring in the type of basalt used, its grain size, court temperature, chemical composition, and emissions associated with the material’s mining, processing, transportation, construction, and maintenance.
The findings indicate that U.S. Green clay courts collectively remove more than 25,000 metric tons of carbon dioxide annually. The study further revealed that 80% of these courts achieve net-zero emissions within 10 years of construction, with a median time of just 3.5 years to become net negative for carbon dioxide. According to the research, 92% of green clay courts reach net zero emissions within 20 years.
This carbon removal capability stems from the leverage of metabasalt, a type of basalt similar to that used in agricultural applications of enhanced rock weathering. The silicate rocks react chemically with rainfall, effectively removing carbon dioxide from the atmosphere. “To mitigate climate change, we need to scale new technologies in addition to leveraging already-existing processes and infrastructure,” Lambert said. “Enhanced rock weathering started in agriculture, and we are now seeing creative and broad-ranging applications such as on coastlines, golf courses, and now our work on tennis courts.”
The study also offers a comparative advantage for green clay courts over traditional hard courts, which are made of concrete and do not contribute to carbon removal through weathering. Construction emissions for green clay courts are 1.6 to 3 times lower than those for hard courts, even before accounting for the carbon sequestration benefits.
However, sequestration rates are not uniform across all courts. The research identified a correlation between temperature and location, with courts in warmer climates and those closer to the primary basalt processing facility in Virginia exhibiting the highest rates of carbon absorption. Approximately 19 courts, located in the coldest regions and furthest from the processing site, are unlikely to achieve net-zero emissions.
Lambert suggests that further optimization of the crushed rock composition and improved tracking of court maintenance could significantly increase the amount of carbon verifiably sequestered. “For new court construction, building a green clay court appears to have less climate impact than a hard court,” he stated. “This provides a great opportunity to organizations and facilities that want to reduce their emissions.”
The research, initially highlighted in January 2026 by Science magazine, builds on previous work quantifying carbon dioxide removal through enhanced weathering. A report published on March 5, 2026, in a Google Groups forum dedicated to Carbon Dioxide Removal, further detailed the study’s findings, emphasizing the potential of green clay tennis courts as a carbon sink.