Another difference is the approach itself. Other models that discuss volcano-atmosphere reactions on Mars focus on how the planet could be warmed, Sholes said, using outgassed volcanic gasses.
"Yes, you need liquid water, but you also need appropriate conditions for life, and here we are finding that the volcanoes should have changed the atmosphere enough to be more conducive to forming complex bio-important molecules," he said.
If the atmosphere was anoxic, scientists may be able to see the evidence on the ground, even billions of years later. That's because anoxic conditions should alter the types of minerals and rocks that form, allowing for testable predictions for future Mars missions. Examples include minerals made of ferrous iron — such as siderite, or iron carbonate — as well as elemental sulfur.
"Our results show that, given models for volcanic activity, during periods of sustained volcanism, Mars’ atmosphere could easily shift towards reducing and anoxic conditions, thus producing measurable amounts of elemental sulfur deposits," Sholes said.