Sulfur dioxide (SO2), a greenhouse gas may have shaped the climate and geochemistry of early Mars, claims a joint research team from the Harvard University and the Massachusetts Institute of Technology. This new finding published in a recent issue of Science offers a clinching evidence that the Red Planet was much warmer than today.

Space probes have revealed that Mars had a warmer climate with the presence of water. This dates back to 3.5 billion years ago.

Scientists tried to unravel what caused warm climate of early Mars. They looked for clues studying Earth’s climate. On Earth, carbon dioxide has a role in making this planet warm and habitable. The volcanoes on Earth erupt and pump carbon dioxide into atmosphere. Silicate rocks trap carbon dioxide and then transform it into calcium carbonate, widely known as limestone. According to scientists, such exchange of carbon dioxide might have been helpful in sustaining life on Earth.

This insight gleaned from earth’s climate didn’t prove handy. For, limestone is not abundant on Mars. But, this led the researchers to think otherwise. Daniel Schrag, senior author of the study, from Harvard claims that it was sulfur dioxide that kept the early Mars warm.

Why suspect sulfur dioxide? Well, this is a powerful greenhouse gas and comes out through volcanic eruptions. On Earth, sulfur dioxide reacts with oxygen giving rise to sulfate. But on Mars, lack of oxygen retained sulfur dioxide for a longer period. Schrag and his colleagues went a step further. They believe that sulfur minerals would form on Mars. But, before forming sulfur minerals, sulfur dioxide contributed to warm climate of Mars. And they might be right. The remotely controlled Mars rovers declared that sulfur minerals prevail on the Martial soil.

This new hypothesis may also shed light on the early atmosphere of Earth. Even researchers may test the new hypothesis searching for traces of sulfur in ancient minerals.