Volcanoes May Have Warmed Mars Enough to Harbor Water

Volcanoes may have warmed Mars enough to harbor liquid water - but only for tens or hundreds of years at a time, according to a new study.

While scientists have previously found evidence of ancient flowing rivers, streams and lakes, it does not indicate that the Red Planet was once a tropical paradise. However, for brief episodes warmth and water once probably characterized Mars, created by greenhouse gases such as sulfur dioxide spewing from volcanoes that became active.

"It's difficult to reconcile this fact with the latest generation of very robust climate models, showing Mars was always very cold and very icy, with an atmosphere too thin to heat the planet enough for water to flow," one of the study's authors, Professor James Head of Brown University, told ABC Science.

The picture of a warmer early Mars is further complicated by the fact that the Sun is much dimmer today than it was billions of years ago.

With scientists in recent years searching for any sign of water on Mars - a hallmark sign of life - either in the past or present, the new findings could have important implications for better understanding our nearest neighbor.

Massive volcanoes are thought to have been active around 3.7 billion years ago, resulting in huge outpourings of lava. And given that on Earth, volcanism often leads to period of cooling rather than warming - sulfuric acid particles and thick ash reflect the Sun's rays, lowering temperatures - scientists just assumed the same could be applied to Mars. But Head and his colleague Itay Halevy conducted their study with the contrasting notion that Mars' dusty atmosphere might have worked differently.

To find out, the duo created a model of how sulfuric acid might react with the widespread dust in the Martian atmosphere. According to their results, sulfuric acid from the volcanoes would have latched onto dust particles, reducing their ability to reflect the Sun's rays and thereby mitigating the cooling effect.

Meanwhile, sulfur dioxide gas would produce a modest greenhouse effect - just enough to warm the Martian equatorial region so that water could flow.

"If you bring the temperature up above freezing for decades to centuries, that melts enough ice and snow to produce the geological features we see in Martian valley networks and open basin lakes, even in a cold and icy early Mars," Head added.

The study is described in further detail in the journal Nature Geoscience.