Evidence for recent climate change on Mars from the identification of youthful near-surface ground ice

• Published in: Nature (London) Vol. 412; no. 6845; pp. 411 - 414
• Main Authors: Mustard, John F, Cooper, Christopher D, Rifkin, Moses K
• Format: Journal Article
• Language: English
• Published: London Nature Publishing 26-07-2001; Nature Publishing Group
• Subjects: Climate; Climate change; Cosmochemistry. Extraterrestrial geology; Earth sciences; Earth, ocean, space; Exact sciences and technology; Extraterrestrial Environment; Extraterrestrial geology; Geology; Ground ice; Ice; Latitude; Mars; Reservoirs; Soils; Surface water; Water; volume; Mars; geomorphology; climate modification; thickness; ground ice; imagery; reservoirs; creep; relative age; skewness; paleoclimate
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/35086515

Ground ice in the crust and soil may be one of the largest reservoirs of water on Mars. Near-surface ground ice is predicted to be stable at latitudes higher than 40° (ref. 4), where a number of geomorphologic features indicative of viscous creep and hence ground ice have been observed. Mid-latitude soils have also been implicated as a water-ice reservoir, the capacity of which is predicted to vary on a 100,000-year timescale owing to orbitally driven variations in climate. It is uncertain, however, whether near-surface ground ice currently exists at these latitudes, and how it is changing with time. Here we report observational evidence for a mid-latitude reservoir of near-surface water ice occupying the pore space of soils. The thickness of the ice-occupied soil reservoir (1-10 m) and its distribution in the 30° to 60° latitude bands indicate a reservoir of (1.5-6.0) × 104 km3, equivalent to a global layer of water 10-40 cm thick. We infer that the reservoir was created during the last phase of high orbital obliquity less than 100,000 years ago, and is now being diminished.