Research at the University of Leeds used a new measurement method to understand Earth’s temperature over the Phanerozoic period, spanning approximately 540 million years ago to the present day. Previous studies estimated planetary temperatures could have reached up to 20 degrees Celsius above preindustrial levels during certain geological periods, possibly reaching 30 degrees above preindustrial in earlier times when animals first evolved.

New research published in Nature Communications reveals that natural feedback processes like rock weathering have regulated Earth’s temperature over millions of years, enabling biosphere evolution. The study concludes past warm periods likely had temperatures around 10 degrees Celsius above preindustrial levels, warmer than today but significantly cooler than previously thought. Researchers suggest these findings are crucial for understanding future climate change impacts and exploring biological evolution and extinction through ancient heat tolerance analysis.

Dr. Dongyu Zheng from Chengdu University of Technology, lead author conducting the work as a visiting fellow at Leeds, stated: “This study shows how ancient rocks and modern climate simulations reveal Earth’s climate boundaries.” He added that “life’s evolution was closely linked to Earth’s ability to regulate its climate over geological time.”

A New Way to Read Ancient Temperatures

Previous oxygen isotope studies suggested tropical oceans were extremely warm historically. Zheng’s team instead used the Chemical Index of Alteration (CIA), which measures the depletion of weatherable elements in rock samples. Their database comprised tens of thousands of readings, allowing temperature reconstruction through combined measurements and climate model simulations. The research also indicated that Earth’s long-term climate sensitivity may be lower than recently proposed.

Professor Benjamin Mills, Professor of Earth System Evolution at Leeds, remarked: “Earth’s temperature has been tightly regulated over time, and human-driven warming of 10 degrees Celsius would take us to places Earth may never have been before.” He emphasized: “Earth’s natural regulation systems are slow, and humans must perform our own climate regulation to keep the planet habitable.”

Journal: Nature Communications
DOI: 10.1038/s41467-026-72672-6
Article Title: Tight regulation of Earth’s long-term temperature over Phanerozoic time
Publication Date: 4-Jul-2026
Funding: UK Research and Innovation