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Friday, December 18, 2009



Good post. People who are new to the Hockey Stick controversy often assume that skeptics and believers are arguing about the shape of the blade. In fact, the issue is the shape of the handle. The hockey stick reconstruction (based largely on tree ring data) argues that temperatures were remarkably consistent for 1000 years and then shot up starting around 1930. But if you remove tree ring proxies from the reconstructions, what you see is exactly what this video shows -- lots of temperature variation. There's nothing remarkable about current temps.


Skepticism is good, but let's not be selective as to what we are skeptical about. We know nothing about the methods or motives behind this video, so we'd need to be pretty gullible to think a 3 minute video trumps all other research.

But anyway lets just accept the video is rock solid science, it looks plausible to me. What's really interesting can be seen at the 2:20 mark. The width of the final warm peak is MUCH wider than the width of all the earlier warm peaks. This fits beautifully with the idea that the advent of agriculture has steadily increased emissions and decoupled the ancient (clearly evident in the video) cycle that previously linked global temperature and ice ages to orbital variation.

If this decoupling caused by agriculture didn't happen we'd have been well into an ice age by now and as the narrator points out that would have been very bad and among other things would have prevented our modern civilisation from developing. So the last 8000 years or so of emissions have been great and we basically owe everything we have created to it. This is all described by Tim Flannery in The Weather Makers.

So far so good. To this point it has all gone our way.

Now for the problem. All our meaningful global infrastructure is only around 200 years old. Its all been built around how the climate is right now. Our present population size and way of life depends entirely on that infrastructure. The investment is huge at its at risk and this risk has never previously been tested.

Its meaningless to argue that we will be okay as the world temperatures have seen bigger swings in the ancient past. When those swings occurred we weren't risking such a massive investment. When those swings occurred our population was tiny. If we had such a swing in the next thousand years, then the problems it would cause us would make any of the things we presently hold out as unspeakable horrors look trivial.

The chart doesn't even tell the whole story, go back the Eocene 50M years ago and we had a hothouse 20 degrees warmer than anything on the chart.

Personally I think our future might yet include an ice age, or it might see problematic warming. It really depends on whether the orbital cycle overwhelms the greenhouse blanket and the truth is no one knows for sure, all we can do is roughly estimate the probabilities of each.

That the Earth warmed or cooled before and the Earth survived provides no comfort at all. The Earth also survived the heavy bombardment by massive comets right after it was formed. The Earth has survived many mass extinctions. The Earth will survive after we are gone. The survival of life on Earth is a guaranteed for the next billion years or so. Our interest is very different to this. We want our way of life to not only survive but also improve. So arguing life on Earth survived some prior event doesn't illuminate anything relevant to the problem at hand. So in the end the video tells us very little.


Jim, thanks for your thoughtful response. To me this analysis does two things: it shows that the Planet is self-regulating (ie it has not runway into a burnt out cinder or flooded Waterworld); and it shows in the recent plateau of warming that we would be better off with a few degrees more warmth, much like the Roman Warm Period and the Medieval Warm Period. We would be much worse off with another Ice Age. Think of the tragic irony if ill-guided attempts to stop warming thrust us into an ice age? We know so little about the real climate science that prudent says to learn much more before doing anything. Easier to prepare for warming (or enjoy it) than goof around with forces we know little about.

The whole climategate scandal simply should remind us to be wary whenever any politician (or scientists) engages in the Politics of Fear and Crisis. If they have to resort to scare tactics, something is wrong in their position.

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