Volcanic sulfur gases may have warmed early Mars and supported potential life

Volcanic sulfur gases may have warmed early Mars and supported potential life
by Clarence Oxford
Los Angeles CA (SPX) Sep 17, 2025

While the ancient Martian climate is still debated, new research indicates that volcanic emissions of sulfur gases could have created a warmer atmosphere capable of sustaining life. The study, published in Science Advances, was led by scientists at The University of Texas at Austin.

Analyzing Martian meteorite data, the team ran over 40 simulations testing how carbon, nitrogen, and sulfur gases behaved under different conditions. Their findings challenge earlier models that emphasized sulfur dioxide (SO2). Instead, they suggest Mars between 3 and 4 billion years ago may have been dominated by reduced sulfur species such as hydrogen sulfide (H2S), disulfur (S2), and possibly sulfur hexafluoride (SF6), a highly potent greenhouse gas.

Lead author Lucia Bellino, a doctoral researcher at UT's Jackson School of Geosciences, said these gases could have generated a hazy atmosphere that trapped heat and supported liquid water. "The degassed sulfur species and redox conditions are also found in hydrothermal systems on Earth that sustain diverse microbial life," she explained.

Unlike previous studies focused on gases released at the surface, this work modeled sulfur's chemical evolution within magmatic systems before eruption. This approach provided a more accurate picture of how volcanic emissions influenced early Mars' environment. The simulations also suggest sulfur frequently changed forms, consistent with Martian meteorites rich in reduced sulfur and surface deposits bonded with oxygen.

NASA's Curiosity rover offered supporting evidence in 2024 when it discovered elemental sulfur in a cracked rock outcrop, the first such finding on Mars. "As S2 was emitted, it would precipitate as elemental sulfur," said coauthor Chenguang Sun, Bellino's advisor. "When we started working on this project, there were no such known observations."

Future modeling will explore whether volcanic activity could have supplied water reservoirs and whether reduced sulfur compounds might have served as an energy source for early microbes in Mars' hydrothermal-like environments. With present-day Mars averaging -80oF, the team hopes their findings inspire climate modelers to estimate how long ancient warming could have lasted and whether it allowed microbial life to persist.

Research Report:Volcanic emission of reduced sulfur species shaped the climate of early Mars