4½ billion years of earth history

Last Thursday, November 12th, I was privileged to attend a lecture and debate in Church House, Westminster, sponsored by The Spectator and chaired by Andrew Neil, entitled “Global Warming: Myth or Reality?”.  The speaker was the prominent Australian climate sceptic, Professor Ian Plimer, author of the recently published book “Heaven and Earth”, which deals with the science of climate alarmism.
 
Professor Plimer (Professor of Geology and Earth Sciences at the University of Adelaide) treated us to a thumb-nail sketch of 4½ billion years of Earth history.  He described how massive changes had taken place in the constituents of the atmosphere, driven by life itself, the introduction of oxygen to the atmosphere, the exchanges of gases between the atmosphere and the oceans, tectonic plate movement leading to massive changes in ocean currents (for example the isolation of Antarctica allowing for permanent glaciation on that continent).  He described six major glaciations or Ice Ages, and pointed out that during five of them, levels of atmospheric CO2 were higher or much higher than today — surely presenting a challenge to today’s warmists.  And at other times the whole earth, poles as well, enjoyed tropical conditions.
 
The Earth, in fact, has had periods when it was much colder than today (with CO2 levels much higher), and other periods when it was much warmer than today.  The IPCC tells us that an increase of 2 degrees celsius could be disastrous, leading to a runaway greenhouse effect, ocean acidification, the dissolution of all crustacea in the oceans, the death of coral.  They will need to explain why none of these disasters seems to have occurred at earlier periods of Earth history when the Earth was much warmer, and the atmosphere much richer in CO2.  As Professor Plimer pointed out, far from being a pollutant, CO2 is an entirely natural trace gas in the atmosphere, which is essential to life, and to plant growth.  Today’s atmosphere is in fact relatively impoverished in CO2 compared to most of the Earth’s history.  Higher levels of CO2 would increase crop yields and rates of biomass generation — perhaps an advantage as we struggle to feed a growing population.
 
As I learned recently, commercial market gardeners using greenhouses will release CO2 into their greenhouses to raise the level from 390 ppm to around 1200 ppm, simply to enhance crop growth.
 
Professor Plimer admitted that the causes of climate change over geological history are not entirely well understood, but the main factors appear to be solar irradiance, variations in Earth orbit, and oscillations in the orbit, leading to long-term climate cycles, other astronomical factors including gas and dust in space, volcanic activity including super-volcanoes (for example the Deccan Traps which may have led to the extinction of the dinosaurs), changes in cloud cover and cloud formation possibly linked to cosmic ray activity, and tectonic plate movement leading to major changes in ocean currents.
 
In the face of all these factors, said Professor Plimer, the idea of taking a single trace gas in the atmosphere, accusing it and finding it guilty of total responsibility for climate change, is an absurdity bordering on madness.  Yet that, it seems, is where we are today as the world’s political processes grind on toward the UN’s COP 15 Climate Conference in Copenhagen in December.

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One Response to 4½ billion years of earth history

  1. Michael St George says:

    Dear Roger

    I too was privileged to be in the audience at Church House last Thursday (and particularly enjoyed your own contribution and that of Lord Christopher Monckton).

    Although a long-time AGW sceptic, and not therefore in any need of conversion or convincing, I thought Prof. Plimer’s exposition of the changes in the Earth’s climate and atmosphere over its life was masterful (and I’ve got and already read “Heaven and Earth”).

    You might perhaps have mentioned that the Monbiot Moonbat had been invited, but declined to come and debate with a proper scientist.

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