London, March 25 (IANS): Around 250 million years ago when dinosaurs roamed the earth, the earth had five times more carbon dioxide (CO2) than today, research shows.

The tectonic movements during that time made the oceans close up and the tectonic plates sink into the earth.

This process, called subduction, led to volcanism at the surface, with rocks constantly melting and emitting CO2 into the atmosphere.

"For the first time, we have quantified in this study the link between plate tectonics and volcanic CO2 emissions - a major step forward in understanding and predicting the behavior of the Earth, and its consequences," said Douwe van der Meer, a researcher at Utrecht University in the Netherlands.

The researchers used an imaging technique called seismic tomography to reconstruct 250 million years of volcanic CO2 emissions.

The researchers analysed earthquake waves travelling through earth, to image the structure of the earth's interior, Livescience reported.

Huge amounts of this greenhouse gas made the climate extremely humid and warm, said Douwe van der Meer, a researcher at Utrecht University in the Netherlands.

The study appeared in the journal Proceedings of the National Academy of Sciences.