Scientists from Weizmann Institute of Science in Israel and Brown University suggest that water flow and warm temperatures on early Mars were likely related to periodic volcanism that spewed tons of greenhouse-inducing sulfur dioxide into the planet’s atmosphere.
This is an artist’s impression of habitable Mars. Image credit: Daein Ballard / CC BY-SA 3.0.
The researchers suggest that periods of temperatures warm enough for water to flow likely lasted for only tens or hundreds of years at a time.
“The latest generation of climate models for early Mars suggests an atmosphere too thin to heat the planet enough for water to flow. The Sun was also much dimmer billions of years ago than it is today, further complicating the picture of a warmer early Mars,” said Prof James Head of Brown University, who is the senior author of the paper published in the journal Nature Geoscience.
“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.”
The current study provides a mechanism for episodic periods of heating and melting of snow and ice that could have each lasted decades to centuries.
The scientists explored the idea that heating may have been linked to periodic volcanism.
Many of the geological features that suggest water flow date to around 3.7 billion years ago, a time when massive volcanoes are thought to have been active and huge lava outpourings occurred.
On Earth, however, widespread volcanism often leads to cooling rather than warming. Sulfuric acid particles and thick ash reflect the Sun’s rays, and that can lower temperatures.
But the team thought the effects of sulfur in Mars’ dusty atmosphere might have been different.
To find out, the researchers created a model of how sulfuric acid might react with the widespread dust in the atmosphere of Mars.
The results suggest that those sulfuric acid particles would have glommed onto 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 so that water could flow.
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Itay Halevy & James W. Head III. Episodic warming of early Mars by punctuated volcanism. Nature Geoscience, published online November 17, 2014; doi: 10.1038/ngeo2293
