The Effect Of Ocean Salinity On Climate And Its Implications For Earth's Habitability

The influence of atmospheric composition on the climates of present-day and early Earth has been studied extensively, but the role of ocean composition has received less attention.

Sea ice coverage for various model configurations and ocean salinities. Rows show the standard model with a fully coupled ocean-atmosphere, sea ice dynamics and freezing point depression ("Full Physics"; top); a modified model configuration with ocean and sea ice dynamics but fixed freezing point for all salinities ("Fixed Freezing Point"; middle); and a slab ocean configuration lacking ocean and ice dynamics but including freezing point depression ("No Dynamics"; bottom). Salinity differs between the columns, increasing from 20 g/kg (left) to 50 g/kg (right). Increasing salinity yields lower ice cover in all scenarios, but the effects are most pronounced in model scenarios that include both dynamical and thermodynamic effects.

We use the ROCKE-3D ocean-atmosphere general circulation model to investigate the response of Earth's present-day and Archean climate system to low vs. high ocean salinity. We find that saltier oceans yield warmer climates in large part due to changes in ocean dynamics. Increasing ocean salinity from 20 g/kg to 50 g/kg results in a 71% reduction in sea ice cover in our present-day Earth scenario.

This same salinity change also halves the pCO2 threshold at which Snowball glaciation occurs in our Archean scenarios. In combination with higher levels of greenhouse gases such as CO2 and CH4, a saltier ocean may allow for a warm Archean Earth with only seasonal ice at the poles despite receiving 20% less energy from the Sun.

Stephanie L. Olson, Malte F. Jansen, Dorian S. Abbot, Itay Halevy, Colin Goldblatt

Comments: Accepted for publication in Geophysical Research Letters 04/19/22
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Atmospheric and Oceanic Physics (; Geophysics (physics.geo-ph)
Cite as: arXiv:2205.06785 [astro-ph.EP] (or arXiv:2205.06785v1 [astro-ph.EP] for this version)
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From: Stephanie Olson
[v1] Fri, 13 May 2022 17:18:16 UTC (1,991 KB)

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