The Other View on Global Warming

Tipped off by blogging's uber conservative, I took an hour and fifteen minutes to view the Channel 4 documentary "The Great Global Warming Swindle," It's well worth a look, and can be found on Google Video.

The film interviews a group of climate change septics, and presents their theories on how the world's climate is regulated. It goes into some length about the systems that drive climate change. In a nutshell, the film argues that variations in climate are caused by changes in the sun's radiated output. It certainly sounded plausible to me.

Predictably, they had a swipe at Al Gore's film "An Inconvenient Truth." In particular, they cited the segment that struck a chord with me, where Gore points out the relationship between climate and CO2 levels. They highlighted an aspect of the relationship that was not mentioned by Gore; that CO2 levels have historically lagged behind changing climate, by a period of about 800 years. On the face of it, this omission seriously damages Gore's argument.

I found it interesting that they didn't press on with their critique of that part of Gore's film. Gore goes on to show the variations in CO2 levels over the past million years, then dramatically demonstrates how present CO2 levels are significantly above the highest previous levels. He concludes with a visual demonstration of the alarming levels of CO2 that will be present in 50 years at the current rate of increase.

It's disappointing that the makers of this film took a swipe at Gore for a critical omission, when they themselves omit to mention the current unprecedented levels of CO2 compared to the highest levels over the past million years.

This is the crux of the argument as I see it. Yes, CO2 levels have historically lagged climate change. I accept climate is a very complex system driven by the sun's energy. But they didn't speculate on what could happen when the relationship between climate change and CO2 levels is reversed, ie, when the change in CO2 levels runs ahead of natural changes caused by variations in the sun's intensity.

In the absence of any natural explanation, and unlike the past, the increase in CO2 levels is being driven by human causes, not by climate change. The sun's still driving the system, but the system now has the new variable of rapidly increasing amounts of CO2.

Footnote: The film covers a broad range of other issues regarding climate change. There are sites providing detailed critiques of the documentary. A couple are here and here.