Mars today is a cold, dry desert, but its surface tells a very different story.
Ancient river channels, lake basins, and minerals formed in water all suggest that billions of years ago, Mars was once a wetter and more Earth-like planet.
One of the biggest questions in planetary science is what happened to all that water—and why Mars changed so dramatically.
A new study published on February 2, 2026, in Communications Earth & Environment brings scientists closer to an answer.
An international research team has discovered that a rare and unusually intense dust storm played a major role in pushing water high into Mars’s atmosphere, where it can more easily escape into space.
Surprisingly, this happened during the Northern Hemisphere summer—a season previously thought to have little influence on water loss.
The study was co-led by Adrián Brines from Instituto de Astrofísica de Andalucía and Shohei Aoki from University of Tokyo and Tohoku University.
Their findings suggest that Mars may have lost its water through more varied and unpredictable processes than scientists once believed.
Dust storms on Mars are nothing new. The planet is famous for massive storms that can sometimes engulf the entire globe.
Until now, most studies focused on those large, planet-wide events as the main drivers of water loss. Scientists also assumed that the Southern Hemisphere summer—when Mars is closer to the Sun and more active—was the key period for water escaping into space.
This new research challenges both ideas. The team observed a powerful but localized dust storm during Martian year 37, which corresponds to 2022–2023 on Earth.
Even though the storm covered only a limited region and occurred in the Northern Hemisphere summer, it had dramatic effects on Mars’s atmosphere.
During the storm, scientists detected an unexpected surge of water vapor in the planet’s middle atmosphere. At certain altitudes, water levels were up to ten times higher than normal. This kind of increase had never been observed before during this season and was not predicted by existing climate models.
Soon after, researchers also measured a sharp rise in hydrogen at the very edge of Mars’s atmosphere, known as the exobase.
Hydrogen levels there increased to about two and a half times higher than in previous years during the same period.
This matters because hydrogen is produced when water molecules break apart under sunlight, and it is light enough to escape into space. Tracking hydrogen loss is one of the best ways scientists estimate how much water Mars has lost over time.
The results suggest that even short-lived, regional dust storms can play a major role in moving water upward and accelerating its escape into space. Over billions of years, these brief but intense episodes may have added up, helping to transform Mars from a wet world into the dry planet we see today.
As Aoki notes, the study adds an important missing piece to the puzzle of Mars’s climate history and shows that Mars’s water loss was likely driven not just by long-term trends, but also by rare and powerful events.
