Earth witnessed extreme global warming around 40mn yrs ago

Washington, Nov 11 (ANI): A new research by scientists has found that variations in atmosphere carbon dioxide around 40 million years ago were tightly linked to changes in global temperature.

Scientists at Utrecht University, working with colleagues at the Nioz Royal Netherlands Institute for Sea Research and the University of Southampton, led the study.

"Understanding the relationship between the Earth's climate and atmospheric carbon dioxide in the geological past can provide insight into the extent of future global warming expected to result from carbon dioxide emission caused by the activities of humans," said Steven Bohaty of the University of Southampton.

The new study focused on one of the hottest episodes of Earth's climate history - the Middle Eocene Climatic Optimum (MECO), which occurred around 40 million years ago.

Their analyses indicate that MECO carbon dioxide levels must have at least doubled over a period of around 400,000 years. In conjunction with these findings, analyses using two independent molecular proxies for sea surface temperature show that the climate warmed by between 4 and 6 degrees Celsius over the same period.

"We found a close correspondence between carbon dioxide levels and sea surface temperature over the whole period, suggesting that increased amounts of carbon dioxide in the atmosphere played a major role in global warming during the MECO," said Bohaty.

The researchers point out that the large increase in atmospheric carbon dioxide indicated by their analysis would have required a natural carbon source capable of injecting vast amounts of carbon into the atmosphere.

The rapid increase in atmospheric carbon dioxide levels around 40 million years ago approximately coincides with the rise of the Himalayas and may be related to the disappearance of an ocean between India and Asia as a result of plate tectonics.

The new findings are published in the journal Science. (ANI)