Mars Without the Southern Perennial CO₂ Cover

Abstract The Martian South Polar Layered Deposits (SPLD) are composed mostly of ice and dust with a thin perennial cover and some internal ice layers. In the North, the seasonal cap is lost during summer, allowing O ice to sublimate into the atmosphere. In the South, the perennial cover prevents O ice sublimation. This work uses the Mars Planetary Climate Model to investigate how the O and cycles are affected if the thin perennial SPLD cover is lost. We find that during southern summer, the atmospheric water content will more than double in the south polar region. However, on a global scale, the NPLD is still the dominant source of humidity because of its larger surface area. When exposing some of the South Polar Cap buried water ice, the south polar cap becomes the dominant source of atmospheric humidity due to Mars's spin‐orbital alignment.