Snowball


 “What distinguishes science from pseudoscience is not whether your theory originated with some particular conviction about how the world works, or whether you feel an emotional attachment to it. What matters is the evidence you find to support it, and whether you are ultimately prepared to accept that it could be wrong.”  Gabrielle Walker, Snowball Earth.

 When, on July 25, 1997, the United States Senate voted 95 to nothing to oppose the Kyoto Protocols under the illusion that doing so would destroy the United States economy, it occurred to me that our reaction to global warming was not going to be nearly as rational as our reaction to the threat posed to the ozone layer by the continued use of chlorofluorocarbons.  Putting aside the science for the moment every positive quarter of economic growth is traditionally attributed to increases in productivity and of course every increase in productivity is due to improvements in efficiency.  Use resources more efficiently and the economy grows.  In 1997 the entire senate was gripped by the irrational fear that further improvements in efficiency would suddenly cause the economy to fall into a tailspin.  The Senate voted 95-0 for Senator Robert Byrd’s 1997 resolution number 98 keeping the United States out of the Kyoto process.  If we all drove Priuses instead of Hummers somehow that would be an economic disaster.  Their logic escapes me, too.  As we all now know, these fine folks did the complete opposite, just in case, and caused the worst economic crises since the Great Depression by voting 90-8 in favor of the Gramm-Leach-Bliley Act in 1999 which in fact did destroy our economy.

 Seeing this coming, I felt compelled to learn the science behind the anthropogenic global warming theory for myself.  I approached this task the way any scientist or engineer would, by reading the peer-reviewed science and climate physics text books. 

 Any discipline of real science is exciting, alive, compelling and leads one to exponentially increasing discovery of even more knowledge and scientific understanding.  Following the scientific trail of AGW led me to the historic papers of Joseph Fourier, Svante Arrhenius and Louis Agassiz and that lead me to the study of the ice ages which inevitably leads one to the greatest ice age catastrophe of all time: Snowball Earth.  Thus, I had already read many of the papers by Paul Hoffman, the hero of Gabrielle Walker’s book as well as those of many other researchers such as Joe Kirchvink and Ray Pierrehumbert.  Knowing the story though did not preclude me from learning a great deal more. 

 Walker is an exceptional writer and her book Snowball Earth is a fascinating account of the development of the snowball Earth theory by the remarkable geologist Hoffman.  In fact the book is full of personal stories not only about Hoffman but many of the geologists who contributed to the development of the theory. 

Brian Harland first proposed that at one time the Earth might have frozen over solid about 600 million years ago because he found evidence of drop stone sediments and glacial scratches in pre-Cambrian rock from all over the world.  But he could not prove it and, if the Earth had in fact frozen over solid, he could not explain how the Earth could have possibly thawed out.  This is because ice is white and reflects all of the short-wave solar radiation back into space.  In other words, once the Earth froze, the sun could no longer warm it up.  Harland published his ideas in 1963.

 Joe Kirschvink first proposed the solution to that problem in a two page paper written in 1992.  Volcanoes emit carbon dioxide at a rate of about 60 million tonnes of carbon a year.  However over geologic time it does not accumulate in the atmosphere because silicate rock weathering, which extracts carbon and buries it as deep ocean sediment, proceeds just as fast.  However, if rocks are covered in ice and snow and if the Earth is so cold that very little water evaporates into the atmosphere, then rock weathering stops and the carbon dioxide accumulates.  Our planet was spared a lifeless fate because of the green house effect of carbon dioxide.  In other words, if Senator Inhofe was right, he would not exist. 

 Paul Hoffman’s place in all this was that he proved the snowball theory.  He was not without adversaries.  The story is full of egos and personalities.  The development and acceptance of the snowball theory is science at its most entertaining and the book reads like a thriller.

There were two episodes of snowball Earth.  The first occurred 2350 million years ago at the boundary between the Archaean and Proterozoic Eons.  Prior to the Earth freezing over solid this first time, atmospheric oxygen is thought to have been just a few hundred parts per million by volume and after the snowball, it had shot up to 1 or 2% of the atmosphere.  Between 750 and 590 million years ago, the Earth froze over again and again oxygen shot up, this time to about the current 20% of the atmosphere by volume.  Thus the most recent episode may have been responsible for the explosion of complex life on Earth, leading ultimately to the evolution of a species which has the mental capacity to actually work it all out and deny it all in one go.  You will enjoy Gabrielle Walker’s book.  It is simply brilliant.

 Tony Noerpel

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