Wickham's musings from Chalke

 
There were two interesting media articles recently; one as a TV programme a week or two ago about the scientists who reject the notion that humans are causing an increase in the earth's average temperature; the other was a Sunday Times article on 11/03/07 showing the current and possible future effects of the global warming.

The sceptical scientists produced lots of data to support their case whilst saying that the current suggestion that the extra carbon dioxide currently being added to the atmosphere by human activities is causing the increase in global average temperature is just guesswork not supported by research data.

The scientists have produced data from several sources showing that over several hundred million years the earth's average temperature has risen several times by anything up to 6 degrees Celsius but the increase in carbon dioxide followed about eight hundred years later. In other words, the increase in temperature warmed the oceans which then released huge quantities of trapped carbon dioxide and methane and the increased areas of desert could not support vegetation so the greenhouse gases were not taken out of the atmosphere.

The principle cause of previous global warming has usually been the sun's increased activity and/or the earth's temporary position closer to the sun.

It is admitted that humans are now adding extra quantities of greenhouse gases to the atmosphere, but nothing like as much as volcanoes added millions of years ago and probably nothing like enough to cause the warming that appears to have started.

We have had higher global average temperatures just a few thousand years ago and a warm period two thousand years ago without adverse effects and the earth returned to a mini ice age in mediaeval times.

It still hasn't been clearly supported by fact or research that the current addition of greenhouse gases is adding to a natural warming effect or that the warming will get out of control, creating a runaway greenhouse effect.

However, my view is that human activities such as clearing forests and adding greenhouse gases are dangerous because they may be making a natural global warming effect much quicker than it would otherwise be. It's not a risk that I consider we should take.

Footnote 29/04/07

Yesterday's paper reported that photographs of Mars have shown less ice at the poles and a darkening of the surface generally compared with comparable photographs taken in the 1970s.

Although the ice does expand and retreat, the difference was still noticeable at similar times of the Martian year. This implies a warming of the Martian climate which could not be caused by human activity so it must be due to solar activity.

The darker surface is probably caused by increased dust storms which would have the effect of trapping more of the sun's heat, compounding the effect.