Green clay tennis courts are able to absorb massive amounts of carbon dioxide via enhanced rock weathering, according to a new study in Applied Geochemistry. Enhanced rock weathering—the process of using silicate rocks like basalt to remove carbon dioxide from the atmosphere through the rocks' chemical reaction with rainfall—has emerged in recent years as a promising method of reducing carbon emissions. Green clay tennis courts in the US are made of metabasalt, a type of basalt with similar properties allowing for carbon sequestration.