A 510,000-Year Record of Mars' Climate

Mars' polar layered deposits record its climate history. However, no deposit yet analyzed provides a global water cycle record that can be tied to a specific orbital history. Here, I fill this gap by analyzing H2O ice layer formation in Mars' south polar Massive CO2 Ice Deposit (MCID), a 510,000-year climate record. Statistical analyses of similar to 10(9) formation model runs compared to observed stratigraphy indicate a variable H2O deposition rate of similar to 1, 0.1, and 0.01 mm yr(-1) at 20, 24, and 28 degrees obliquity, respectively-likely recording the obliquity-dependent midlatitude-to-pole H2O transport rate. The MCID record allows unprecedented obliquity-driven H2O ice deposition rate derivation because of its well-defined age relative to other deposits and its CO2 cold-trapping effect, which simplifies local seasonal and long-term H2O flux. The recovery of an orbit-resolved H2O transport rate is an essential step in elucidating Mars' global, orbit-driven water cycle.

Automated summary

By analyzing the Massive CO2 Ice Deposit (MCID) in Mars' south polar region, researchers have filled the gap in global water cycle records and provided insights into Mars' climate history. The study reveals that the deposition rate of H2O ice is variable and dependent on the obliquity of Mars.