The early Martian climate remains a mystery to planetary scientists, but Martian meteorites offer some clues. Understanding these processes helps explain what types of sulfuric gases were released and how they contributed differently to the early Martian climate. Today, sulfur samples collected on Mars vary depending on location: surface samples often show sulfur bonded with oxygen, while meteorites contain large amounts of reduced sulfur. “This indicates that sulfur cycling – the transition of sulfur to different forms – may have been a dominant process occurring on early Mars,” Bellino said. The paper, “Volcanic Emission of Reduced Sulfur Species Shaped the Climate of Early Mars,” appeared in Science Advances on September 3, 2025.