The Palaeocean-CO₂ team recently published the most complete history of how CO₂ has changed over the last 66 million years. The data collected shows more clearly than ever before the link between CO₂ and climate.
Colleagues from St. Andrews (James Rae), Texas A&M University (Yige Zhang, Xiaoqing Liu), the University of Southampton (Gavin Foster, Ross Whiteford) and the Swiss University ETH Zürich (Heather Stoll) pulled together data collected over the last 15 years using high-tech laboratory techniques. Samples were taken from cores of mud from the deep-sea floor, where microscopic fossils and ancient molecules accumulate, preserving a story of what CO₂ and the climate looked like at the time.
Caption: The history of atmospheric CO₂ levels and global average temperature over the last 60 million years: the CO₂ scale shows CO₂ in terms of doublings, as this is the key control on climate.
Dr. James Rae, from the University of St Andrews School of Earth and Environmental Sciences, who led the international team explained: “For instance, the last time CO₂ was as high as it is today enough ice melted to raise sea level by 20 metres and it was warm enough for beech trees to grow on Antarctica.
“If we allow fossil fuel burning to continue to grow, our grandchildren may experience CO₂ levels that haven’t been seen on Earth for around 50 million years, a time when crocodiles roamed the Arctic.”
Dr. Rae added: “CO₂ has transformed the face of our planet before, and unless we cut emissions as quickly as possible, it will do it again.”
Reference: “Atmospheric CO2 over the Past 66 Million Years from Marine Archives” by James W.B. Rae, Yi Ge Zhang, Xiaoqing Liu, Gavin L. Foster, Heather M. Stoll and Ross D.M. Whiteford, 31 May 2021, Annual Review of Earth and Planetary Sciences.