Scientists have long puzzled over the presence of liquid water on ancient Mars, which is surprisingly warm given its distance from the sun. A new study by Harvard researchers has shed light on this enigma by uncovering a previously unknown mechanism driving the Martian climate’s fluctuations.
The team, led by Danica Adams, used photochemical modeling to analyze the early Martian atmosphere and its relationship with hydrogen. They found that between 4 and 3 billion years ago, Mars experienced episodic warm spells lasting around 40 million years, interspersed with cold periods of varying lengths.
The study suggests that crustal hydration – water being lost to the ground – supplied hydrogen into the atmosphere over millions of years, driving these temperature fluctuations. During warm periods, the CO2 in the atmosphere recycled back into its components, creating a cycle of warming and cooling.
“This study synthesizes atmospheric chemistry and climate for the first time,” Adams said. “It makes a great case study for how planets can evolve over time.”
The research has implications for understanding the conditions that supported prebiotic chemistry – the building blocks of life as we know it – during warm periods, and challenges our understanding of life’s persistence on Mars during cold intervals.
More information is available online at Nature Geoscience (2025). DOI: 10.1038/s41561-024-01626-8
Source: https://phys.org/news/2025-01-red-planet-hot-cold-history.html