Archives for September 12, 2006

I’ve been in Hong Kong two days now and I haven’t seen the sun yet.

My hotel room has a magnificent view over the harbour. I did see some sun beams early yesterday morning penetrating through the smog haze over the harbour – but no sun.

Photograph taken looking from Hung Hom (Kowloon) east to the island of Hong Kong from the top of the Harbour Plaza Hotel on 11th September 2006 at about 3pm.

It’s an eight hour flight from Brisbane to Hong Kong and I tuned the screen in the back of the seat in-front of me to Al Gore’s new movie ‘An Inconvenient Truth’ and watched the movie a couple of times. I had already seen it at a cinema in Brisbane the day before, so I’ve now seen ‘An Inconvenient Truth’ three times.

It’s a mighty piece of propaganda in which Gore doesn’t let a single inconvenient truth get in the way of his thesis that the earth is already experiencing dramatic climate change as a result of extremely elevated carbon dioxide levels.

Early in the movie there is a cartoon depicting a ‘Mr Sunbeam’ marching down to earth only to be trapped and then beaten up by some ‘global warming thugs’. An analogy is made between the bodies of dead ‘sunbeams’ piling up within the earth’s atmosphere and planet earth overheating.

Gore is correct to indicate that carbon dioxide levels have risen dramatically over recent decades, but he is wrong to suggest there has been a corresponding dramatic increase in temperature. Global air temperatures have only risen by about 0.6C over the last 30 years – though more dramatically at the Arctic. He suggests sea temperatures have also risen dramatically as an explanation for the veracity of hurricane Katrina.

Gore was correct to indicate that with global warming there should be a corresponding increasing in rainfall and snowfall, but it is unclear to me whether this has actually been the case. I understand more snowing is falling on Greenland, but less on the Australian Alps.

Gore went on to claim more rain is falling in more extreme events giving the example of Mumbai (India) in July 2005. He also indicated that rainfall patterns are changing with places like the African Sahel experiencing more extreme drought.

In the movie, all of this was attributed to rising levels of atmospheric carbon dioxide. There was no mention in the movie of global dimming, which a growing scientific literature* suggests has the effect of reducing global temperatures as well as potentially reducing rainfall and snowfall by affecting both cloud droplet coalescence and ice precipitation formation. There is also potential for this phenomenon to change precipitation patterns, with the pollution from Australia’s capital cities and industrial areas potential creating a downwind rain shadow.

Global dimming is a consequence of increasing levels of urban and industrial pollution with man-made airborne aerosols having the effect of sending Al Gore’s ‘Mr Sunbeams’ back into space, in effect saving them from the global warming thugs depicted in the cartoon in the movie.

So the haze that has been hanging over Hong Kong, can potentially counteract the increasing levels of carbon dioxide. This potentially explains why global temperatures have not increased dramatically.

Of course there are other explanations, but given the anticipated growth in the Chinese and other economies, and the likely corresponding increase in air pollution, shouldn’t Gore have at least acknowledged the issue?

Al Gore’s movie purports to present facts and information in a thoughtful and compelling way. But Gore so simplifies and exaggerates just one aspect of our understanding of climate physics that it would perhaps have been more honest to have called the movie ‘A Plug for Anthropogenic Global Warming Wthout All The Inconvenient Truths’.

——————————————————————–
* I was recently sent the following very interesting papers on global dimming and its potential impact on rainfall in Australia: Rosenfeld, D. (2000) Suppression of rain and snow by urban and industrial air pollution. Science, Vol 287, pp 1793-1796. Rosenfeld et. al. (2005) Potential impacts of air pollution aerosols on precipitation in Australia. Clean Air and Environmental Quality, Vol 40, No. 2, pp 43-49. Rosenfeld, D. (2006) Aerosols, Clouds and Climate. Science, Vol 312, pp. 1323 – 1324. ABC TV Four Corners did a feature on global dimming in March 2005, the transcript and reference documents can be found here: http://www.abc.net.au/4corners/content/2005/s1328747.htm

I’m hoping to publish a few blog pieces on the movie and invite guest posts from others: email your contribution to jennifermarohasy@jennifermarohasy.com .