6000 BC

Here's an interesting piece of data. It's from the Greening Earth Society, whose Mission Statement is as follows :

The Greening Earth Society provides a scientifically-sound perspective on the increasing atmospheric carbon dioxide (CO₂ concentration and global climate change.

Well, maybe. I say "maybe" because it is not just overwhelmingly sceptical about Kyoto and the effect of human activity on global temperature - as sceptical as I am - but because it is completely one-sided. As one-sided as the many sites with the opposite view, which never quote any data which might undermine their preconceived opinion.

The chart on the right comes from an article by William Ruddiman, former chairman of the University of Virginia environmental sciences department, and his research team in Quaternary Research Reviews. It shows an increasing concentration of Methane starting in about 5000 BC, which correlates pretty well with the domestication of ruminant herbivores (cows, sheep, goats), and the start of paddyfield rice farming - two major Methane producers.

Methane is 21 times more Greenhouse-y than CO₂. (Source : Worldchanging.com). But the impact is still less than the impact of the additional CO₂, because the amount is so much less.

Another source of methane - which might well overwhelm the contribution of cattle and paddyfields - is the swampy tundra exposed by the end of the last Ice Age. This Ice Age peaked about 20,000 years ago, with much of Europe and North America covered in glaciers 2 km deep. It's last gasp was about 7,000 years ago, when the permanent Arctic Ice cap retreated off major land masses.

The map at the right shows the coverage of Ice over the last 20,000 years, with contours showing how the ice retreated.

The CO₂ concentration is more problematic. It doesn't correlate well with human activity, as Humans have been using "slash and burn" techniques for 40,000 years, which radically change the CO₂ levels - sometime decreasing them as hungry new growth sucks up Carbon, while the charred remnants of old-growth get buried along with much of their carbon content.

The atmospheric CO₂ concentration has been growing steadily in a linear fashion for the last 8000 years. Which again correlates well with the glacial retreat, but not human activity. There's no evidence of a population explosion 8000 years ago, and if anything, we stopped building so many campfires when the Ice retreated.

The article in "Greening Earth" posits that this increased atmospheric CO₂ concentration is all that is staving off another Ice Age. It only takes a drop of 2 Celsius to cause one.

They may be right.

On the other hand, there's data over the last 1000 years that shows global temperatures to be more strongly correlated with Solar Output than anything else. The Sun is an unusually variable star for its position on the main sequence, something that might explain why Intelligent life is found here, and not everywhere. Perhaps the best conditions for "growing" intelligent life are a (slightly) variable star to cause Ice Ages (a booster to Evolution), a Double-Planet system to cause tectonic activity (but not too much) (another booster to Evolution) and tides (very important when moving from single-celled to multi-cellular organisms), and a massive Gas Giant or Failed star a long way out to help sweep up asteroids so planets in the "goldilocks zone" where water is liquid don't have their reset buttons pushed too often by Dinosaur-killers. (The Earth-Moon binary system is a double-planet one, though we don't normally think of the Moon as a planet, and Jupiter is an excellent vacuum cleaner of comets - see Schmacher-Levy).

It could be that the situation is considerably worse in the medium term (the next 5-10,000 years) than the Greenhouse Believers state. We may get hit with a double-whammy of increased solar output (which would normally cause the glaciers that should be covering Europe by now to retreat), and increased CO₂. Something like this could cause the Methane Hydrate that's buried in the ocean floor to evaporate - then we'd have a *real* problem, with temperatures rising a degree or more in a relatively short time as the oceans fizz.

Certainly I believe that we need more data, and models which explain what the heck has happened over the last 10-20,000 years. Something none, repeat, none, of the current computer climate models do. The ones that Kyoto is based on.

It is my evaluation that the Greenhouse Theory is junk science, to put it bluntly. But that we need to study what the heck really is going on, and do what we can, within reason, to slow down the growth of human-emitted CO₂, until we know more about what the cause of atmospheric composition is, and what the effects are. "First, do no harm".

Right now though, we have a big problem, due to politics and vested interests. There are people on both sides of the Greenhouse debate who believe the Greenhouse theory is correct. There are also people, again on both sides of the debate, who believe the theory is completely bogus.

On one side, the "true believers" who look at the evidence, and see Venus in our future unless we get off our backsides. With them are people who think it's all hogwash, but that the Kyoto accords are harmless, and who don't want to risk their Academic careers being terminated for being "politically incorrect". It has happened, and only rarely has a happy ending. You want money for research, you toe the Party Line.

On the other side, you have people who look at the evidence, and see that we don't know nearly enough to make any sane conclusion, but that there's nothing we can do for good or ill that will have much effect in the next 200 years or so. You also have people who are "True Believers" in Global Warming, but figure that a technological fix will be found (as it always has been in the past) and who look at the costs of doing something and say "Let others get pay for it, not me". You want money for research, you say what Big Energy wants you to say.

"Oh, what Fools these Mortals Be!" and all that jazz.