Volcanic Eruptions on Mars May Have Caused Flowing Water

It's clear now that water once flowed on the surface of ancient Mars. Yet this fact is hard to reconcile with new models of the Red Planet that show that in the past, it was likely eternally icy. Now, researchers have proposed that warming and water flow on Mars was episodic and likely related to ancient volcanic eruptions.

Quite a bit has been learned about Mars in recent years. Yet this has deepened the mystery of the planet's ancient water in some respects. For example, the latest generation of climate models for early Mars suggests that the planet possessed an atmosphere that was too thin to heat the planet enough for water to flow.

"These new climate models that predict a cold and ice-covered world have been difficult to reconcile with the abundant evidence that water flowed across the surface to form streams and lakes," said James Head, one of the researchers, in a news release. "This new analysis provides a mechanism for episodic periods of heating and melting of snow and ice that could have each lasted decades to centuries."

The researchers created a model to test how volcanism might possibly cause warmer temperatures. More specifically, they examined how sulfuric acid might react with widespread dust in the Martian atmosphere. The model revealed that the sulfuric acid particles would have attached to dust particles, which would reduce their ability to reflect the sun's rays. Meanwhile, sulfur dioxide gas would produce a modest greenhouse effect-just enough to warm the Martian equatorial region.

"The average yearly temperature in the Antarctic Dry Valleys is way below freezing, but peak summer daytime temperatures can exceed the melting point of water, forming transient streams which then refreeze," said Head. "In a similar manner, we find that volcanism can bring the temperature on early Mars above the melting point for decades to centuries, causing episodic periods of stream and lake formation."

When active volcanism ceased on Mars, so did the possibility of warmer temperatures and flowing water. Not only does this study show a bit more about the history of Mars, but it also shows where the fossilized remains of life might be found on Mars, if it ever existed.

The findings are published in the journal Nature Geoscience.