塩が地球とその先の生命の鍵を握っているかもしれない(Salt may be the key to life on Earth and beyond)

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2022-06-02 パデュー大学

大気の組成、特に温室効果ガスの多寡は、地球の気候に影響を与える。地球・大気・惑星科学部門のステファニー・オルソン助教授率いるパデュー大学の研究者たちは、海水中の塩分の存在も地球や他の惑星の居住性に大きな影響を与えることを最近発見しました。研究チームは気候モデルを用いて、海水中に溶ける塩分の量が異なる世界の気候を調査し、塩分の多い海は暖かい気候になる傾向があり、その結果、惑星が生命を宿すのに役立つと予測しました。

<関連情報>

海洋の塩分濃度が気候に与える影響と地球の居住可能性への影響 The Effect of Ocean Salinity on Climate and Its Implications for Earth’s Habitability

Stephanie Olson,Malte F. Jansen,Dorian S. Abbot,Itay Halevy,Colin Goldblatt
Geophysical Research Letters  Published: 24 May 2022
DOI:https://doi.org/10.1029/2021GL095748

Abstract

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. 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 versus 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 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.

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