The current image of Mars as an arid and hostile desert contrasts sharply with the history revealed by its surface. Channels, minerals altered by water, and other geological traces indicate that the Red Planet was, in its early days, a much wetter and more dynamic world. Reconstructing how this water-rich environment disappeared remains one of the great challenges of planetary science. Although several processes are known that can explain some of this loss, the fate of much of Martian water remains a mystery.
A new study from an international team of researchers published in Communications: Earth & Environment on February 2, 2026, has brought us a significant step closer to solving this puzzle. For the first time, researchers demonstrated that an anomalous, intense, but localized dust storm was able to drive the transport of water to the upper layers of the Martian atmosphere during the Northern Hemisphere summer - a time when this process was previously considered to be irrelevant.
"The findings reveal the impact of this type of storm on the planet's climate evolution and opens a new path for understanding how Mars lost much of its water over time," says Adrián Brines, a researcher at the Instituto de Astrofísica de Andalucía (IAA-CSIC) and co-lead author of the study along with Shohei Aoki, a researcher from the Graduate School of Frontier Sciences at the University of Tokyo and the Graduate School of Science at Tohoku University.
While dust storms have long been recognized as important for Mars' water escape, previous discussions have mostly focused on large, planet-wide dust events. In contrast, this study shows that smaller, regional storms can also strongly enhance water transport to high altitudes, where it can be more easily lost to space. Furthermore, previous research has focused on the warm, dynamic summers of the Southern Hemisphere, since it is typically the main period of water loss on Mars.
This study detected an unusual increase in water vapor in the middle atmosphere of Mars during the Northern Hemisphere summer in Martian year 37 (2022-2023 on Earth), caused by an anomalous dust storm. At these altitudes, the amount of water was up to ten times greater than usual, a phenomenon not observed in previous Martian years and not predicted by current climate models.
Shortly afterward, the amount of hydrogen in the exobase - the region where the atmosphere merges with space - increased significantly to 2.5 times that of the previous years during the same season. One of the keys to understanding how much water Mars has lost is measuring how much hydrogen has escaped into space, since this element is readily released when water breaks down in the atmosphere.
"These results add a vital new piece to the incomplete puzzle of how Mars has been losing its water over billions of years, and shows that short but intense episodes can play a relevant role in the climate evolution of the Red Planet," concludes Aoki (University of Tokyo and Tohoku University).
This study is a collaborative, international project combining data across multiple Mars exploration missions such as the Trace Gas Orbiter (TGO) of the ESA's ExoMars mission (2016) and its NOMAD instrument with observations from other active missions in Martian orbit, such as NASA's Mars Reconnaissance Orbiter (MRO) and the Emirates Mars Mission (EMM).