Climate puzzle over life's origin
SCIENTISTS at the CRPG-CNRS University of Lorraine, The University of Manchester and the Institut de Physique du Globe de Paris have ruled out a theory as to why the planet was warm enough to sustain the planet's earliest life forms when the Sun's energy was roughly three-quarters the strength it is today.
Life evolved on Earth during the Archean, between 3.8 and 2.4 billion years ago, but the weak Sun should have meant the planet was too cold for life to take hold at this time; scientists have therefore been trying to find an explanation for this conundrum, what is dubbed the 'faint, young Sun paradox'.
"During the Archean the solar energy received at the surface of the Earth was about 20 to 25 % lower than present," said study author, Dr Ray Burgess, from Manchester's School of Earth, Atmospheric and Environmental Sciences. "If the greenhouse gas composition of the atmosphere was comparable to current levels then the Earth should have been permanently glaciated but geological evidence suggests there were no global glaciations before the end of the Archean and that liquid water was widespread."
Source: Science Daily