Earth’s Temperature Stayed Pretty Steady for 540 Million Years

Scientists have long tried to figure out how warm the planet was in the deep past. Most earlier work used oxygen isotopes found in fossils, which suggested that Earth has cooled steadily over the last 539 million years. However, those studies left a lot of questions unanswered. A new approach looks at chemical weathering patterns in ancient sandstones and mudrocks from around the world. Researchers combined these data with a cutting‑edge climate model that simulates how air, water and land interact over long periods. The results are surprising. They show that the planet’s average temperature has stayed between 10 and 30 °C for the entire Phanerozoic era.This means that oceans in the Paleozoic were not as scorching as some earlier studies claimed; they were similar to later periods. The findings point to powerful balancing forces in Earth’s climate system. Processes like silicate weathering, which removes carbon dioxide from the atmosphere and locks it into rocks, appear to have kept temperatures in check for hundreds of millions of years. This stability would have allowed life to adapt and evolve continuously. In short, Earth’s long‑term climate is more controlled than previously thought, thanks to natural feedback loops that keep global heat levels from swinging wildly.