Greenhouse Gases Increased Ancient Martian Temperature Allowing Water to Flow

Greenhouse gases increased the ancient Martian temperature high enough to allow liquid water to flow.

According to a latest research finding led by Ramses M. Ramirez, a doctoral student along with James Kasting, Evan Pugh Professor of Geosciences at Penn State, nearly 3.8 billion years ago the presence of molecular hydrogen along with carbon dioxide and water created a greenhouse effect that increased the Martian temperatures high enough to allow liquid water to flow.

Prior to this, climate models were used to produce temperatures that were warm enough for liquid water to flow. But these models were limited to just carbon dioxide and water, which proved unsuccessful. But in this study, the researchers created a model using carbon dioxide, water as well as hydrogen molecules to create a temperature warm enough to above freezing. Above the freezing temperature the liquid water was able to flow across the Martian surface nearly 3.8 billion years ago, which is what is observed in the ancient Martian valley networks like the Nanedi Valles.

"This is exciting because explaining how early Mars could have been warm and wet enough to form the ancient valleys had scientists scratching their heads for the past 30 years," said Ramirez. "We think we may have a credible solution to this great mystery."

They also produced an alternative theory in which they blamed the collision of the planet with large meteorites for the formation of the Martian valley. But this process could not have produced water in large enough volume to carve the valleys.

"We think that there is no way to form the ancient valleys with any of the alternate cold early Mars models," said Ramirez. "However, the problem with selling a warm early Mars is that nobody had been able to put forth a feasible mechanism in the past three decades. So, we hope that our results will get people to reconsider their positions."

A one dimensional climate model was created to investigate the possibility that gas levels from volcanic activity could create sufficient hydrogen and carbon dioxide to form greenhouse effect and increase the temperature enough to allow the liquid to flow.

The model was finally tested using hydrogen absorption data that was used to replicate the condition of ancient Mars.

"It's kind of surprising to think that Mars could have been warm and wet because at the time the sun was much dimmer," Ramirez said. "The hydrogen molecule is symmetric and appears to be quite boring by itself.  However, other background gases, such as carbon dioxide, can perturb it and get it to function as a powerful greenhouse gas at wavelengths where carbon dioxide and water don't absorb too strongly. So, hydrogen fills in the gaps left by the other two greenhouse gases."

The findings were documented in the journal Nature Geosciences.