English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The debate over the early Martian climate is among the most intriguing inplanetary science. Although the geologic evidence generally supports a warmerand wetter climate, climate models have had difficulty simulating such ascenario, leading some to suggest that the observed fluvial geology (e.g.valley networks, modified landscapes) on the Martian surface, could have formedin a cold climate instead. However, as we have originally predicted using asingle-column radiative-convective climate model [Ramirez et al. 2014a],warming from CO2-H2 collision-induced absorption (CIA) on a volcanically activeearly Mars could have raised mean surface temperatures above the freezingpoint, with later calculations showing that this is achievable with hydrogenconcentrations as low as ~1%. Nevertheless, these predictions should be testedagainst more complex models. Here, we use an advanced energy balance model thatincludes a northern lowlands ocean to show that mean surface temperatures nearor slightly above the freezing point of water were necessary to carve thevalley networks. Our scenario is consistent with a relatively large ocean ashas been suggested. Valley network distributions would have been global priorto subsequent removal processes. At lower mean surface temperatures and smallerocean sizes, precipitation and surface erosion efficiency diminish. The warmperiod may have been ~< 10 million years, perhaps suggesting that episodicwarming mechanisms were not needed. Atmospheric collapse and permanentlyglaciated conditions occur once surface ice coverage exceeds a thresholddepending on CIA assumptions. Our results support an early warm and semi-aridclimate consistent with many geologic observations.

Climate Simulations of Early Mars With Estimated Precipitation, Runoff, and Erosion Rates