For more than a quarter billion years, coral reefs did far more than brighten shallow seas. Long before humans appeared, these living structures helped guide how Earth recovered from major climate shocks. New research shows reefs played a quiet but powerful role in setting the rhythm of the planet’s carbon cycle. The study reveals that shallow-water reef systems influenced how quickly Earth stabilized after massive carbon dioxide changes. These ancient ecosystems did not simply react to climate shifts. They helped control how long recovery took. Scientists from the University of Sydney and Université Grenoble Alpes traced these patterns back to the Triassic Period, more than 250 million years ago. Their work connects reef growth, ocean chemistry, and climate recovery in a way not fully understood before. “Reefs didn’t just respond to climate change, they helped set the tempo of recovery,” said Associate Professor Tristan Salles of the University of Sydney’s School of Geosciences. Modeling the warm-water carbonate habitability across time. (CREDIT: PNAS) Reefs and the Planet’s Carbon Balance Carbon dioxide has long shaped Earth’s temperature. …