When our planet was young, it would have been showered with light that was only 70 per cent the intensity that our Sun emits now. What this means is that the Sun was quite faint and, according to astronomers such as Carl Sagan and George Mullen in 1972, it wouldn’t have been able to support water in a liquid consistency, but more of a frozen one. This is what astronomers refer to as the Faint Young Sun paradox.
Teams of scientists from all over the world have traced back into the Earth’s early years and suggested that its atmosphere could have harboured more greenhouse gases. Choking carbon dioxide might have been higher as well as the pressure by about ten times. Methane might well have also been extremely prevalent, actively driving the greenhouse effect and reacting with oxygen to manufacture even more carbon dioxide along with water vapour.
Other researchers have since come forward stating that a high pressure along with carbon dioxide might well have been high enough to stop our young planet from freezing over. Others have suggested a cycle that could have stopped to bring ice age periods and start back up again thanks to the eruptions of volcanoes spewing out carbon that warmed the atmosphere in a greenhouse effect.
Image Credit: PIK