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Hydrogen-Nitrogen Greenhouse Warming in Earth's Early Atmosphere

2013; American Association for the Advancement of Science; Volume: 339; Issue: 6115 Linguagem: Inglês

10.1126/science.1225759

1095-9203

R. Wordsworth, Raymond T. Pierrehumbert,

Solar and Space Plasma Dynamics

Understanding how Earth has sustained surface liquid water throughout its history remains a key challenge, given that the Sun's luminosity was much lower in the past. Here we show that with an atmospheric composition consistent with the most recent constraints, the early Earth would have been significantly warmed by H(2)-N(2) collision-induced absorption. With two to three times the present-day atmospheric mass of N(2) and a H(2) mixing ratio of 0.1, H(2)-N(2) warming would be sufficient to raise global mean surface temperatures above 0°C under 75% of present-day solar flux, with CO(2) levels only 2 to 25 times the present-day values. Depending on their time of emergence and diversification, early methanogens may have caused global cooling via the conversion of H(2) and CO(2) to CH(4), with potentially observable consequences in the geological record.