New research finds that ancient rocks release as much CO2 as volcanoes

Rocks contain an enormous store of carbon in the ancient remains of plants and animals that lived millions of years ago. Research has shown that the geological carbon cycle acts as a vital regulation of Earth’s temperature: for example, natural chemical weathering of rocks absorbs CO2, when certain minerals are attacked by the weak acid found in rainwater. This process has helped to counteract the continuous CO2 released by volcanoes around the world.

However, a new study, released on October 4, 2023, has shown that in taking into account an additional natural process, weathering rocks may actually release CO2 into the atmosphere in similar volumes to volcanoes. Currently, this process is not included in most models of the natural carbon cycle.

The process occurs when rocks that formed on ancient seafloors, where plants and animals were buried in sediments, are pushed back up to Earth’s surface when mountains like the Himalayas or Andes form. This exposes the carbon from the remains of dead organisms in the rocks to oxygen in the air and water, which can react and release CO2.