Last night, I watched an interesting programme on Britain's Channel 4 television channel - "Global Warming Swindle" - which argued the global warming we are experiencing now was not man-made. Rather, it argued that global warming was just the normal variation of the climate due to variability of the sun's ouput. If this were true, then efforts to reduce our energy use and carbon emissions on sites such as this would be misguided.

So was the programme right? I'd dearly love to know.

I should declare that I am one of the instigators of this site, and so, in a sense, have an "interest" in believing in man-made global warming. However, I trained as a physicist, did a PhD in atmospheric pollution modelling, and believe passionately in science. If the facts did show that global warming was natural, then I would accept that and turn my attention to something else worthwhile.

Here's my take on what the programme said. Some of the arguments it made were obviously wrong, for example:

  • "CO2 makes up a small proportion of the atmosphere so how can it have such a big effect?" That's nonsense - many physical processes are affected by things that occur in small quantities - witness the Ozone hole, catalysts in chemical reactions - or try eating a small amout of deadly poison.

  • "Why didn't the temperature rise at the same time as the world industrialised?" Well as the programme itself said there is often a time lag between changes in the air or sea, and this affecting temperature, and in any case, emissions have grown enormously recently.

  • "Global Warming campaigners have an interest in hindering developement in poorer countries" - well most people I've met who work against climate change are also interested in improving the lives of poorer people.

So one has to ask, if the programme's arguments were so compelling, why did it need to include these red herrings? Still, despite that, some arguments it made seemed more plausible:

  • the ice core record shows that temprature rises and then Carbon Dioxide concentration rises - implying that rising temperature causes increased Carbon Dioxid not the other way around;

  • if increased CO2 were the cause of global warming, you'd expect the biggest temperature increases in the upper atmosphere (in the troposphere at 10Km above the ground). However, satellite and air-balloon studies don't show this.

  • there is a very good correlation between sun spot activity and global temperature - a much better correlation than between CO2 and global temperature. Thus it's changes in the Sun that is cuasing global warming not human greenhouse gas emissions.

  • the oceans, the soild and animals emit far far more CO2 than we humans produce - so how can our emissions have such a large effect?

On the face of it these seem more serious points. I don't know how true they are, but I am going to spend some time trying to find out.So more to come....

If anyone has some information or views please add a comment or write your own article.