Paul MacRae, June 13, 2008

David Attenborough is the narrator of the brilliant Planet Earth nature series and many other excellent nature documentaries. And so it’s sad to see him appear in a video on YouTube being hosed by a climate scientist’s so-called computer-generated “proof” that humans are the main cause of global warming.

In the YouTube video (“Sir David Attenborough: The Truth About Climate Change,” taken from a documentary series of the same name), Attenborough is shown a chart (see below) of the temperature rising (red line), natural variation (green line), which climatologist Peter Cox explains as being caused by volcanoes, solar variation, etc., and the greenhouse effect produced by humans (yellow line). All of this data is being supplied by a computer climate model.

Attenborough surveys climate model
Attenborough surveys climate model graph

Attenborough is impressed, and concludes: “So there you have it. There seems little doubt that this recent rise — this steep rise in temperature — is due to human activity.”

The only problem with this little scenario is that it’s completely speculative, and there are plenty of doubts. One of the key problems in climate science is distinguishing between natural variation and human causes, to the point where even the UN’s Intergovernmental Panel on Climate Change has to use measures of probability to pin the blame on humans (“it is highly likely that humans are causing….”). Yet, as meteorologist Roy W. Spencer has pointed out:

Contrary to what you have been led to believe, there is no solid published evidence that has ruled out a natural cause for most of our recent warmth – not one peer-reviewed paper. The reason: our measurements of global weather on decadal time scales are insufficient to reject such a possibility.(1)

The second problem is, as we’ve noted elsewhere on this site, is that the temperature (the red line) is no longer rising, while the yellow line is. So, it’s hard to see how the yellow line (carbon dioxide emissions) could be the main reason for changes in the red line.

The belief that warming is principally caused by human carbon emissions is completely unwarranted based on the evidence available. But, then, unfortunately, ideology long ago replaced evidence when it comes to the issue of global warming, an ideology that even clings to the belief that the planet is warming when it hasn’t for the last 10 years. Why else would the IPCC bring out a report in 2007 saying the human effect on warming is becoming increasingly apparent, when there’s been no warming since 1998? Clearly the IPCC is more interested in printouts from computer models than the real-world data, because the real data doesn’t match its theory that humans are to blame.

This is, perhaps, why in the video the red line ends at the year 2000, the point at which the climate flat-lined, even though Attenborough’s series first aired in 2006. A flat red line wouldn’t have fit the bias of the documentary. Even so, in the YouTube version screenshot, you can see the red line dropping from the El Nino year of 1998, while the yellow line continues upward.

And the falling green line? Pure speculation, since even the most sophisticated climate models still can’t tell the difference between human-caused and natural variation. That said, the green line may well be going down since the planet isn’t warming right now.

Attenborough, as a respected scientific commentator and naturalist in his own right, should know better than to take computer models as gospel while ignoring paleo-geographic evidence from the real world that today’s climate variations are well within normal limits. But, then, he’s just one of millions being hosed at the moment.

(1). Roy W. Spencer, “The Sloppy Science of Global Warming,” March 20, 2008. Available at