Snowball Earth

If you have ever wondered about the Snowball Earth theory, then this article in New Scientist will be one that you will want to read, Early Snowball Earth may have melted to a mudball . One part I found especially interesting:

THE idea that Earth was entirely frozen over about 700 million years ago – the so-called Snowball Earth hypothesis – poses one small problem: how did our planet thaw out? The conundrum could be explained if the Earth was more mudball than snowball.

Evidence for Snowball Earth comes from the discovery of glacial rock formations around the world that date back to this time. One proposed explanation for the subsequent thawing is that carbon dioxide levels soared during the freeze, warming the planet. But recent studies of oxygen isotopes suggest that the level of CO2 was only a tenth of that required to melt the ice.

Now Dorian Abbot and Raymond Pierrehumbert of the University of Chicago have used climate models to study how dust from volcanoes and the weathering of rocks would affect the thaw. They found that in regions where the amount of snowfall was low and any snow that did settle was sublimating away, enough dust would have accumulated to change the surface albedo sufficiently so that the Earth absorbed sunlight and thawed (Journal of Geophysical Research – Atmospheres, DOI: 10.1029/2009jd012007, in press).