Al Gore leaving his mark on Sheffield

I am merely a computer scientist who once was interested in computer models of global climate for some time. Usually I try to only speak up when I think, that my education allows me to do so. But after having watched the video An Inconvenient Truth, which was shown in the university’s lecture theatre, I have to object to the way things have been presented in the movie.

I would have expected Al Gore to be up to date with the state-of-the-art. Especially after having given his presentation so many times, you would expect a more factual discussion of the subject.

Before I continue I have to point out, that I’m not arguing against protecting the environment. There already is sufficient reason to do so (deforestation, overfishing, ground emaciation, air pollution). However I repeat Jaworowski’s appeal to keep the discussion on the scientific side instead of allowing politicians and activists to implement recommendations based on distorted science.[6]

A closer look at the facts makes you realise that Al Gore’s video An Inconvenient Truth is giving a false picture of the factual situation:

False claims [1], [2], [8], [16], [18], [19]:

“This study concluded that 75% of the 928 articles either explicitly or implicitly accepted the consensus view (on global warming being caused by human activities) the remainder of the articles covered methods or paleoclimate and did not take any stance on recent climate change.”

The study evaluated a limited number of papers (by filtering using the keyword “global climate change”) and claims that there is a scientific consensus on global warming being caused by human activities. Albeit the study is claiming it, scientific consensus on this issue has not been reached. Furthermore counting papers is a rhetorical argument lacking scientific rigour. is a collection of articles which will give you a different picture of “scientific consensus”.

Extreme climate changes do not prove human activities to be the reason [2], [3]:

As many amateur astronomers know the polar caps of Mars are melting. Apparently Mars is experiencing a period of global warming as well. Observing extreme weather conditions does not prove human activities to be the reason.

Correlation does not imply causation[2], [12]:

Observing a rise in CO2 levels and global temperature does not prove the greenhouse effect. The relationship between historic temperatures and CO2 levels, based on ice-core samples, actually shows that carbon dioxide increases have always followed a rise in temperature rather than the other way around. Essenhigh points out that an estimated 90 billion tons of carbon as carbon dioxide annually circulate between the earth’s ocean and the atmosphere (compared to man-made sources’ emission of about 5 to 6 billion tons per year). As temperature rises, the carbon dioxide equilibrium in the water changes, and this releases more carbon dioxide into the atmosphere.

Selective use of data [9]:

Ice core based CO2 estimates range from 160 ppm to 700 ppm with some readings as high as 2450 ppm. Direct measurements taken by scientists during the 19th century ranged from about 250 ppm to 550 ppm with an average of 335 ppm. Global warming alarmists, however, prefer to estimate pre-industrial CO2 indirectly by means of ice core measurements, from which they derive the much lower pre-industrial revolution estimate of 280 ppm.

The analysis of the Vostok and Siple ice cores presented as conclusive evidence could be flawed [6], [4], [5], [15]:

The curve showing historical CO2 content was measured using gas chromatography. The samples were obtained by crushing the ice in a vacuum at very low temperature without melting it. Z. Jaworowski however pointed out as early as 1994 that the ice cores are not fulfilling the closed system criteria because even the coldest Antarctic ice (-73°C) does contain water, which could dramatically change the chemical composition of the air bubbles trapped between the ice crystals. Jaworowski points out that the dissociation pressure of CO2 is 5 bars and the data is showing a clear inverse correlation between the decreasing CO2 concentrations, and the load-pressure increasing with depth.

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[23] The Great Global Warming Swindle (video)

[24] The Jaworowski story

More thoughts and comments to comments:

Thanks to everyone for the feedback.

Before anyone will get me wrong I would like to say, that I don’t intend to criticise the organizers of this event for doing so. The issue I have with the video is, that it is trying to shape public opinion by selecting facts and jumping to conclusions and things need to be discussed. Apparently it seems to be moral to convince people about a upcoming disaster no matter how, as if they are not to be trusted. I am not surprised, that Jaworowski is being accused of being biased after having worked in this area this long. Myself I only had to wait a few hours to be accused of this.

Measuring historical global temperature is very difficult, because in contrast to measuring CO2-content it is a much more local phenomenon. Only in recent times global temperature measurement has improved a great deal thanks to satellite measurements and the satellite measurements are indicating an increase in global temperature. I was pointed out the temperature diagrams of the 2001 IPCC study showing short-term global and long-term northern hemisphere temperature[13]. And yes, I do agree that CO2 is a green house gas and humans are contributing 9 billion tons per year to it.

At this point the documentaries usually jump to the conclusion. I have pointed out the problems with measuring historical CO2-records already. I have also pointed out, that the amount and the importance of the CO2 increase has been highly overestimated. Simplified computer models led to predictions forecasting a global warming of 0.5° per decade and more. But the CO2 greenhouse effect is not a simple independent system. To put things into perspective, one should furthermore consider, that

Looking at earth’s history with all it’s ice ages, at the history of the atmosphere’s oxygen content, and at other planets (think about Jupiter’s red spot), one can see that there have been climate changes dwarfing the changes we are observing in present history.

Environmentalism IS necessary and it is being practised. There is sufficient reason (and really conclusive evidence) for being concerned and it is not true, that scientists have failed to draw public attention to it: depletion of fossil fuel, deforestation, exponential growth of the worlds population and famine, water pollution, air pollution, … These issues are being neglected while political and public attention is focussed on reducing CO2-emissions.

I don’t think it is a good attitude to say: “It doesn’t matter if people are lobbying, as long as it is for the good cause.”. Sitting back and hoping that the people will do the right thing for the wrong reason usually does not work out very well. If there is reason to believe that the CO2 content of the atmosphere is not a good benchmark for measuring the impact of human activities, this has to be debated! In the mean time Al Gore has been recruited as UK adviser on environmental science.

To soften things up a bit: I do agree with the end of the video, where it is saying: “plant a tree … walk more … separate your waste …”.

I do not have a car, I avoid printing out documents, I reuse plastic bags, I repair things instead of throwing them away, I wear a pullover in the house instead of turning up the heater, and I switch of my computer now.

After the heated discussion

I got a lot of material to read and think about and I admit, that I was not up-to-date with some things. If Jaworowski’s argument does not hold, the ice-core argument breaks down. If I will get convinced about the need to reduce CO2 emissions (and I admit, that I’m much less sure about part of what I have written earlier), it will be because of people doing quality research and open scientific discussions.

I ask you to not blindly trust either Al Gore or me. Do a survey for yourself and form your own opinion!

Further reading [15], [17], [18], [19], [20], [21], [24]