New Climate Model Reveals Methane Did Not Warm Ancient Earth

Researchers from the University of California - Riverside have recently refuted a long-held theory that the Earth, billions of years in the past, stayed warm with the help of methane.

According to a study published in the journal Proceedings of the National Academy of Sciences, unlike today that the planet is rapidly heating due to greenhouse gases, ancient Earth needed more heat because the Sun was 10 to 15 percent dimmer than what it's today.

Because of the presence of a weaker Sun, the planet needed the help of heat-trapping gases to make the water on Earth foster life. Scientists assumed that methane played a large part in heating ancient Earth as its heating capacity is 34 times stronger than carbon dioxide. However, the researchers found out that there was actually not enough methane in the past, Science Daily reports.

"A proper accounting of biogeochemical cycles in the oceans reveals that methane has a much more powerful foe than oxygen. You can't get significant methane out of the ocean once there is sulfate," said Stephanie Olson, lead author of the study.

By creating a numerical model that is divided into 15,000 three-dimensional regions, the researchers calculated the sulfate reduction, methane production and other biogeochemical cycles in the ancient past.

Results showed that unlike past climate models (which claim that methane was 300 parts per million in the past), it was only 1 to 10 parts per million. This is because the presence of sulfate in water destroys methane.

Because of this discovery, scientists need to determine what greenhouse of mixture of greenhouse gases was responsible for heating Earth.

"If we detect methane on an exoplanet, it is one of our best candidates as a biosignature, and methane dominates many conversations in the search for life on Mars. Yet methane almost certainly would not have been detected by an alien civilization looking at our planet a billion years ago -- despite the likelihood of its biological production over most of Earth history," said professor Tim Lyons from UC Riverside.