Ancient Mars was a frozen ball of ice but massive plumes of methane may may have caused warm spells that allowed liquid water in the planet to flow, findings of a new study have revealed.

Mars Used To Be Covered With Liquid Water

The Red Planet is now cold and dry but evidence suggests that its surface was once covered with streams, ponds, lakes, rivers and even seas and oceans during its first billion years.

Earlier analysis of Martian rocks hinted that the planet's climate was sometimes warm enough to allow lakes to form and last for thousands of years. Scientists wondered what events may have resulted in these rare and long-lasting climates.

Although Martian volcanoes may have emitted bursts of greenhouse gases, the impact would not have lasted very long. Now, Edwin Kite, from University of Chicago, and colleagues, found that liquid water on young Mars could be attributed to thawing caused by the explosive bursts of methane, a heat-trapping greenhouse gas.

Clathrates And Methane

Unlike our home planet, Mars does not have a large moon that can keep it from wobbling so its axis of rotation tilts in a chaotic and unpredictable manner that can result in regular temperature changes.

Kite and colleagues suggest that during the warmer periods, ice that covered Mars shrank which led to clathrates hidden below the Martian surface to decompose. Clathrates are materials composed of methane trapped in cages of ice.

The clathrates then explosively released methane when they destabilized. The researchers said that one outburst alone may have released 200 trillion tons of the greenhouse gas into the Martian atmosphere. These outbursts may have increased the temperatures on the planet by 9 to 18 degrees Fahrenheit.

"We find that outgassed methane can build up to atmospheric levels sufficient for lake-forming climates, if methane clathrate initially occupies more than 4% of the total volume in which it is thermodynamically stable," the researchers wrote in their study. "We conclude that methane bursts represent a potential pathway for intermittent excursions to a warm, wet climate state on early Mars."

Methane would have gradually broken down in the atmosphere but researchers said that a warming episode may have persisted for as long as a million years.

"The release of methane trapped in Martian subsurface reservoirs following planetary obliquity shifts may have contributed to episodic climate warming between 3.6 and 3 billion years ago, explaining evidence for ancient ice-covered lakes," wrote Alberto Fairen of the Centro de Astrobiologia and Cornell University, in a commentary.

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