Ice Ages in the early history of the earth

3 Apr 2010

Getting back to March 31st 2010 another geologist claims to have solved a mystery - why earth's surface was not a big lump of ice four billion years ago when radiation from the sun was thought to have been weak. Previously, scientists had assumed the atmosphere then consisted of 30 per cent C02 trapping heat like a greenhouse (but see Peter Warlow's talk at the SIS Autumn Meeting a couple of years ago). Carl Sagan and George Mullen formulated the 'faint early sun paradox' - the paradox being that the earth's climate was fairly constant during billions of years of time, even though it was estimated radiation from the sun has increased by 25 per cent. Hence, if there had been a weak sun many years ago - why wasn't earth frozen? In 1993 atmospheric scientist Jim Kasting reformed some 'theoretical calculations' that showed 30 per cnet of the atmosphere consisted of C02 - suggesting the earth was cocooned in a deep layer of greenhouse gases that prevented the planet freezing over. It's weird how all these strand of research end up with desirable conclusions and this seems to suggest most studies are attempts to iron out bumps in prevailing theories and consensus views. Actual, free radical research hardly ever happens - but that is simply human nature at work, scientists are no different to the rest of us, in spite of what they claim.

The mystery, it is said, has been solved. What stopped the Ice Age forming was not excessive C02 levels - but a thin cloud layer. In addition, the surface of the earth at that time was covered in water. This meant the sun cold warm the water unobstructed by a thick layer of clouds - it was nearly all blue skies. As therer was no algae or plants to produce the chemical mix to make clouds form not many cloud could have existed. This is such a beautiful bit of work one can only admire them - and how they actually got there is even more wonderful. They examined the world's oldest bedrock - in western Greenland. An analysis of this rock showed that C02 atmospheric levels were one part per thousand - three to four times more than they are today. However, it was nowhere near the required 30 per cent - and bang went one theory and in came another one.