Surprise! Study says Late Jurassic CO2 was 1,200 ppm, dipped to 750 ppm in the Cretaceous
6 hours ago Anthony Watts
Press release from University of Göttingen: T-Rex Dinosaur teeth give glimpse of early Earth’s climate
The study shows that the late Jurassic atmosphere carried about 1,200 ppm of CO₂, about four times the pre industrial 1850 benchmark of 280 ppm. By the late Cretaceous, CO₂ it had dipped to near 750 ppm.
A previously untapped source of data sheds new light on the climate of the early Earth: fossilized dinosaur teeth show that the atmosphere during the Mesozoic era, between 252 and 66 million years ago, contained far more carbon dioxide than it does today. An international research team at the Universities of Göttingen, Mainz and Bochum made this discovery by analysing oxygen isotopes in tooth enamel. They used a newly developed method that opens up opportunities for research into the Earth’s climate history. In addition, the researchers found that total photosynthesis from plants around the world was twice as high as it is today. This probably contributed to the dynamic climate during the time of the dinosaurs. The results were published in the journal PNAS.
The research team analyzed the enamel of dinosaur teeth found in North America, Africa and Europe dating from the late Jurassic and late Cretaceous periods. Enamel is one of the most stable biological materials. It records different isotopes of oxygen that the dinosaurs inhaled with every breath that they took. The ratio of isotopes in oxygen is affected by changes in atmospheric carbon dioxide and photosynthesis by plants. This correlation allows researchers to draw conclusions about the climate and vegetation during the age of the dinosaurs.
Tooth of a Tyrannosaurus rex – like the teeth analyzed in this study – found in Alberta, Canada Photo: Thomas Tütken
In the late Jurassic period, around 150 million years ago, the air contained around four times as much carbon dioxide as it did before industrialization – that is, before humans started emitting large quantities of greenhouse gases into the atmosphere. And in the late Cretaceous period, around 73 to 66 million years ago, the level was three times as high as today. Individual teeth from two dinosaurs – Tyrannosaurus rex and another known as Kaatedocus siberi which is related to Diplodocus – contained a strikingly unusual composition of oxygen isotopes. This points to CO₂ spikes that could be linked to major events such as volcanic eruptions – for example, the massive eruptions of the Deccan Traps in what is now India, which happened at the end of the Cretaceous period. The fact that plants on land and in water around the world were carrying out more photosynthesis at that time was probably associated with CO₂ levels and higher average annual temperatures.
https://wattsupwiththat.com/2025/08/11/surprise-study-says-late-jurassic-co2-was-1200-ppm-dipped-to-750-ppm-in-the-cretaceous/
