12:24pm Friday 18th July 2008
RE:SNOW IN 1907 (BFP July 11)
UNLESS those who still follow the IPCC's crusade can satisfactorily answer last week's question posed by Anthony Weeden, we should continue to deride their persistent prattle claiming that mankind is
responsible for global warming'.
The pre-historic variations in global mean surface temperature referred to by Mr Weeden incorporate the results of analyses of ice core drillings made by the British Antarctic Survey in the 1990s.
These were published in The Royal Commission on Environmental Pollution's 22nd Report in June, 2000 (RCEP 22).
Fig.2-V of that report, entitled Energy -the Changing Climate', shows the near-synchronous variations in local surface temperature and atmospheric carbon dioxide content which occurred during the past 450,000 years or so. Approximately every 100,000 years during that period, the Earth's local surface temperature, close to the South Pole, dropped jerkily from a peak to a trough about 13 degrees C lower, and then jumped back smoothly and rapidly to a similar peak.
In sympathy - though actually several decades afterwards - the carbon dioxide content fell jerkily from a peak of about 300 parts per million by volume (ppmv) to a trough of about 180 ppmv, then rose (rapidly and mostly smoothly) back again to a similar peak.
From my own calculations of the greenhouse effect of global warming, assuming solar radiation to be constant during that period (which it clearly was not), the 120 ppmv change in carbon dioxide level could not have induced a global warming change of more than about 0.5 degrees C. These calculations also show that trimming carbon dioxide levels by the colossal 60% or so aimed at in the latest IPCC jamboree could not reduce the global mean surface temperature by more than about 0.25 degrees C assuming constant solar input.
Atmospheric water - in the form of vapour, liquid (cloud and rain) and solid (ice) - is by far the dominant greenhouse substance, swamping the small effects of carbon dioxide in even the highest concentrations we can possibly generate by burning carbonaceous fuels as if there were no tomorrow.
Cloud, as well as forming a significant part of the greenhouse blanket', is also a potent shield against the Sun's rays. By increasing its extent during prolonged warm periods it reflects solar energy back into space, and by reducing its extent during prolonged cold spells it lets more sunshine through. It thus acting as an automatic Venetian blind.
The carbon dioxide changes in the Vostok Ice Sheet core analyses can be explained as the result of photosynthesis.
A warm Earth stimulates plant growth and subsequent decay to produce both methane (a potent greenhouse gas) and carbon dioxide.
A cold Earth arrests plant decay and thus inhibits carbon dioxide production, while photosynthesis at a reduced rate continues to deplete the atmosphere's stock of this gas.
Pre-historic global warming is therefore clearly due mainly to causes other than carbon dioxide, and - since this is fundamentally an energy phenomenon - it has to be attributed to variations in solar energy received by the Earth. Changes in the Earth's orbit (the Milankovitch theory) and orientation (axial tilt and precession of the equinoxes) clearly play some part, but these are minor in comparison with changes in the Sun's energy output. Why? Simply because the shape of the temperature/time curve due to gravitational effects has to be symmetrical in order to be repeatable, whereas the dominant shapes shown of RCEP's Fig.2-V are strongly asymmetrical.
I suggest that these solar energy changes are the result of continuing variations in the Sun's internal thermo-nuclear activity. One explanation could be that the Sun alternately accretes interstellar hydrogen and deuterium by its intense gravitational power during periods when energy output is low, then brakes - or halts - such accretion when energy levels increase.
The rapid rise in radiation pressure which follows increasing core temperature propels interstellar matter away from the Sun, forming a powerful buffer.
Gravitational attraction acts much more gently during the longer decay period. There are, perhaps, other viable explanations Yes, mankind certainly affects global warming a little by the burning
of fossil fuels, and even just by breathing! But by far the greatest effect is created by the Sun's inherent energy variations, however caused, and to a lesser extent by the changes in the Earth's
orbit and the tilt of its axis of rotation. So there we have it!
Roderick Taylor
Chartered Engineer
Abbotsbrook
Bourne End
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