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Volcanism And Greenhouse Gas May Have Given Mars Episodic Flowing Water
Brett Smith for redOrbit.com – Your Universe Online
Scientists have speculated that Mars was very similar to Earth in the past, with numerous flowing rivers and lakes.
However, a new study in the journal Nature Geoscience has indicated that flowing water on Mars may have only taken place during relatively short periodic episodes of global warming driven by volcanic activity.
The new study is based on researchers looking at the result of volcanism using the latest climate simulations of early Mars. The models indicated intervals of warm temperatures lasting long enough for flowing water to have existed for periods lasting tens or hundreds of years.
“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,” study author James W. Head, professor of earth, environmental and planetary sciences at Brown University, said in a statement. “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.”
Newer climate simulations for early Mars indicate an atmosphere too wispy to allow for flowing water for long stretches of time. The sun was also much less bright billions of years ago, lowering the chances of flowing water on an early Mars.
The researchers said they suspected periodic volcanism may have led to warming and flowing water. A lot of the geological features indicate water flow dates back to approximately 3.7 billion years ago, a time when enormous volcanoes are believed to have been productive, spewing massive lava outpourings.
Here on Earth, extensive volcanism has led to periods of cooling as opposed to warming, as sulfuric acid particles and thick ash reflect the sun’s rays and reduce temperatures. However, the study team suspected the results of a high amount of sulfur in Mars’ dusty atmosphere may have been different.
To determine what the impact of volcanism might have been, the scientists created a simulation of how sulfuric acid might interact with extensive dust in the Martian atmosphere. Their effort found that sulfuric acid debris would have attached to dust particles, greatly reducing their capability to reflect the sun’s rays. At the same time, sulfur dioxide gas from the volcanism would create a small greenhouse effect – barely enough to warm the area around the equator, allowing water to flow.
The study team compared the environment of early Mars to that of cold desert conditions found in the McMurdo Dry Valleys in Antarctica.
“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,” Head said. “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.”
The Brown scientist said his new study might be used to offer clues on where fossil evidence of life on Mars could be found, if at all.
“Life in Antarctica, in the form of algal mats, is very resistant to extremely cold and dry conditions and simply waits for the episodic infusion of water to ‘bloom’ and develop,” he said. “Thus, the ancient and currently dry and barren river and lake floors on Mars may harbor the remnants of similar primitive life, if it ever occurred on Mars.”
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