February 13, 2024
Planetary scientist Edwin Kite considers the climate shifts of Mars based on surface sediment.
Surface observations indicate that Mars’s early climate supported liquid water—rivers and lakes—for over a billion years. But like Earth, which has experienced both global ice ages and extreme heat over the past eon, Mars’s climate history may have been intermittent.
A study by Edwin Kite, associate professor of Geophysical Sciences, and Susan Conway at the University of Nantes, examining sediment and erosion evidence suggests that Mars did not dry out in a single transformation; rather, Mars experienced seven major climate transitions, periodically able to support liquid water even beyond its first billion years. The study also evaluates hypotheses for the cause of these climate shifts, such as volcanic eruptions and changes in the planet’s axial tilt.
A gallery of images below helps tell the story.
Valley networks record a time period of significant wetting (a). A River delta from Jezero crater (b).
Delta close-up: steep-dipping planar beds (flat, parallel layers of sediment) mark the past boundary between river and lake (NASA/JPL-Caltech/ASU) (c). Sulfate-rich aeolian dunes (created by wind) from Victoria crater (NASA/JPL-Caltech/Cornell) (d).
Dark-toned hardened aeolian dunes can be seen above a region showing different erosion patterns from a period of significant drying (dashed line). That gap cuts through light-toned clay-rich deposits from Mars’s lake era. Distant light-toned background rocks (at left) probably postdate all low-latitude rivers on Mars (NASA/JPL/MSSS).
Possible trajectories (including reversals) of climate on Mars. Warm and wet: with rain, rivers, lakes, and groundwater closer to the surface. Sediment accumulates in or near lakes, and hills are shaped gradually by soil movement. Warm and dry: dominated by wind-driven erosion of layered rocks and moving dunes. Slopes are modified by rockfall (a type of rapid landslide). Cold and wet: periodic surface melting of snow and ice-covered lakes. A channel that carries melted water dissects a debris-covered glacier. Layered lake sediments and sections of frozen and unfrozen ground over potentially deep groundwater are present. Cold and dry: with limited snowfall, debris-covered glaciers, a frozen landscape, and layered rock formations.
Kite, E.S., Conway, S. Geological evidence for multiple climate transitions on Early Mars. Nat. Geosci. 17, 10–19 (2024).