Early oxidation of the martian crust triggered by impacts

Despite the abundant geomorphological evidence for surface liquid water on Mars during the Noachian epoch (>3.7 billion years ago), attaining a warm climate to sustain liquid water on Mars at the period of the faint young Sun is a long-standing question. Here, we show that melts of ancient mafic clasts from a martian regolith meteorite, NWA 7533, experienced substantial Fe-Ti oxide fractionation. This implies early, impact-induced, oxidation events that increased by five to six orders of magnitude the oxygen fugacity of impact melts from remelting of the crust. Oxygen isotopic compositions of sequentially crystallized phases from the clasts show that progressive oxidation was due to interaction with an 17O-rich water reservoir. Such an early oxidation of the crust by impacts in the presence of water may have supplied greenhouse gas H2 that caused an increase in surface temperature in a CO2-thick atmosphere.

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A review of meteorite evidence for the timing of magmatism and of surface or near-surface liquid water on Mars

Journal of Geophysical Research Atmospheres ◽

10.1029/2005je002402 ◽

2005 ◽

Vol 110 (E12) ◽

Cited By ~ 57

Author(s):

Lars Borg

Keyword(s):

Liquid Water ◽

Near Surface ◽

Water On Mars ◽

Surface Liquid

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Carbonate-silicate cycle predictions of Earth-like planetary climates and testing the habitable zone concept

Nature Communications ◽

10.1038/s41467-020-19896-2 ◽

2020 ◽

Vol 11 (1) ◽

Author(s):

Owen R. Lehmer ◽

David C. Catling ◽

Joshua Krissansen-Totton

Keyword(s):

Liquid Water ◽

Physicochemical Parameters ◽

Silicate Weathering ◽

Habitable Zone ◽

Two Dimensional ◽

Land Area ◽

Incident Flux ◽

Earth Like Planets ◽

Surface Liquid ◽

Log Linear

AbstractIn the conventional habitable zone (HZ) concept, a CO2-H2O greenhouse maintains surface liquid water. Through the water-mediated carbonate-silicate weathering cycle, atmospheric CO2 partial pressure (pCO2) responds to changes in surface temperature, stabilizing the climate over geologic timescales. We show that this weathering feedback ought to produce a log-linear relationship between pCO2 and incident flux on Earth-like planets in the HZ. However, this trend has scatter because geophysical and physicochemical parameters can vary, such as land area for weathering and CO2 outgassing fluxes. Using a coupled climate and carbonate-silicate weathering model, we quantify the likely scatter in pCO2 with orbital distance throughout the HZ. From this dispersion, we predict a two-dimensional relationship between incident flux and pCO2 in the HZ and show that it could be detected from at least 83 (2σ) Earth-like exoplanet observations. If fewer Earth-like exoplanets are observed, testing the HZ hypothesis from this relationship could be difficult.

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Improving the snow physics of WEB-DHM and its point evaluation at two SnowMIP alpine sites

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-7-3481-2010 ◽

2010 ◽

Vol 7 (3) ◽

pp. 3481-3519 ◽

Cited By ~ 1

Author(s):

M. Shrestha ◽

L. Wang ◽

T. Koike ◽

Y. Xue ◽

Y. Hirabayashi

Keyword(s):

Surface Temperature ◽

Liquid Water ◽

Snow Depth ◽

Hydrological Model ◽

Snow Water Equivalent ◽

Bias Error ◽

Snow Albedo ◽

Basin Scale ◽

Snow Water ◽

Snow Physics

Abstract. The snow physics of a distributed biosphere hydrological model, referred to as the Water and Energy Budget based Distributed Hydrological Model (WEB-DHM) is improved by incorporating the three-layer physically based energy balance snowmelt model of Simplified Simple Biosphere 3 (SSiB3) and the Biosphere-Atmosphere Transfer Scheme (BATS) albedo scheme. WEB-DHM with improved snow physics (WEB-DHM-S) can simulate the variability of snow density, snow depth and snow water equivalent, liquid water and ice content in each layer, prognostic snow albedo, diurnal variation in snow surface temperature, thermal heat due to conduction and liquid water retention. The performance of WEB-DHM-S is evaluated at two alpine sites of the Snow Model Intercomparison Project with different climate characteristics: Col de Porte in France and Weissfluhjoch in Switzerland. The simulation results of the snow depth, snow water equivalent, surface temperature, snow albedo and snowmelt runoff reveal that WEB-DHM-S is capable of simulating the internal snow process better than the original WEB-DHM, with the root mean square error and bias error being remarkably reduced. Although WEB-DHM-S is only evaluated at a point scale for the simulation of snow processes, this study provides a benchmark for the application of WEB-DHM-S in cold regions in the assessment of the basin-scale snow water equivalent and seasonal discharge simulation for water resources management.

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Future surface mass balance and surface melt in the Amundsen sector of the West Antarctic Ice Sheet

The Cryosphere ◽

10.5194/tc-15-571-2021 ◽

2021 ◽

Vol 15 (2) ◽

pp. 571-593

Author(s):

Marion Donat-Magnin ◽

Nicolas C. Jourdain ◽

Christoph Kittel ◽

Cécile Agosta ◽

Charles Amory ◽

...

Keyword(s):

Mass Balance ◽

Liquid Water ◽

Ice Sheet ◽

Surface Mass Balance ◽

Surface Mass ◽

Ice Shelves ◽

Net Production ◽

West Antarctic ◽

Surface Liquid ◽

Surface Melt

Abstract. We present projections of West Antarctic surface mass balance (SMB) and surface melt to 2080–2100 under the RCP8.5 scenario and based on a regional model at 10 km resolution. Our projections are built by adding a CMIP5 (Coupled Model Intercomparison Project Phase 5) multi-model-mean seasonal climate-change anomaly to the present-day model boundary conditions. Using an anomaly has the advantage to reduce CMIP5 model biases, and a perfect-model test reveals that our approach captures most characteristics of future changes despite a 16 %–17 % underestimation of projected SMB and melt rates. SMB over the grounded ice sheet in the sector between Getz and Abbot increases from 336 Gt yr−1 in 1989–2009 to 455 Gt yr−1 in 2080–2100, which would reduce the global sea level changing rate by 0.33 mm yr−1. Snowfall indeed increases by 7.4 % ∘C−1 to 8.9 % ∘C−1 of near-surface warming due to increasing saturation water vapour pressure in warmer conditions, reduced sea-ice concentrations, and more marine air intrusion. Ice-shelf surface melt rates increase by an order of magnitude in the 21st century mostly due to higher downward radiation from increased humidity and to reduced albedo in the presence of melting. There is a net production of surface liquid water over eastern ice shelves (Abbot, Cosgrove, and Pine Island) but not over western ice shelves (Thwaites, Crosson, Dotson, and Getz). This is explained by the evolution of the melt-to-snowfall ratio: below a threshold of 0.60 to 0.85 in our simulations, firn air is not entirely depleted by melt water, while entire depletion and net production of surface liquid water occur for higher ratios. This suggests that western ice shelves might remain unaffected by hydrofracturing for more than a century under RCP8.5, while eastern ice shelves have a high potential for hydrofracturing before the end of this century.

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