Young sun paradox (Introduction)
The early sun, 3.5 billion years ago when life started, was 20% cooler. More CO2 and methane in our atmosphere solves the issue:-http://phys.org/news/2013-07-early-earth-life.html
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The early sun, 3.5 billion years ago when life started, was 20% cooler. More CO2 and methane in our atmosphere solves the issue:-http://phys.org/news/2013-07-early-earth-life.html
Complete thread: