ocean. Here, some of the carbon gets locked up in carbonate rocks. Where tectonic plates dive back into the mantle at subduction zones, some of this carbon (much of it in the form of limestone) can get buried in the mantle for millions, even billions of years. In this way, the tectonic conveyor belt removes carbon from the atmosphere, and that should eventually reduce carbon dioxide levels and generate colder climates. Today we know that much more carbon is buried within the mantle than is present on Earth’s surface or in its atmosphere. Of course,
