Researchers from England presented simulations, the results of which indicate that the amount of carbon dioxide on Earth has dropped sharply. This happened about 30 million years ago.
A new study, led by the University of Bristol, showed that declining atmospheric CO2 was instrumental in the transition of Earth’s climate from a warm greenhouse to a cold glacial about 34 million years ago. In the coming centuries, this transition may be partially offset by anthropogenic increases in CO2 concentration.
They found that between 40 and 34 million years ago, the Earth’s climate underwent significant climatic changes. Until 40 million years ago, in the Eocene, Antarctica was covered with lush forests, but by 34 million years ago, in the Oligocene, these forests were replaced by thick continental ice sheets, as in modern Antarctica. The main reason for the transition from a greenhouse to an ice age is widely discussed, and there is little information about how the climate on land has changed. An international team of scientists used molecular fossils preserved in ancient coals to reconstruct the temperature on land during this transition.
To reconstruct the change in temperature, the team took a new approach to coal deposits from the Gippsland Basin in southeastern Australia. These deposits span over 10 million years of Earth’s history and have been detailed by study staff at the University of Melbourne.
New data show that land temperatures cooled at the same time as ocean temperatures and by a similar amount – about 3 degrees. To investigate the reasons for this drop in temperature, the team ran climate simulations. Only simulations involving a decrease in atmospheric CO2 concentration were able to reproduce cooling consistent with temperature data reconstructed from sediments.