59abd191_Quark_Soup_by_David_Appell__ode_Highlights_HIDE_HIGHLIGHTS
[Time] 12:45
Russ: So, we had Martin Weitzman on recently, who, with Gernot Wagner is the author of Climate Shock. And he takes--Weitzman takes what he calls a precautionary approach, a fat-tailed approach. He says, 'True, it's not so likely that we are going to have catastrophic warming, but since there is a chance, a prudent approach is to take precautions and to reduce the possibility of that catastrophic outcome.' In fact, his--the level that he's worried about is the 700 parts per million--I think we're around 400 right now? Do I have that right? Guest: Yes. Russ: High 300? Guest: Yes. 0.04% or 0.07% is I think a more accurate way of describing it, but it doesn't sound so big. So they [?]. Russ: Right. So, it's parts per million. So, it's a small number. But that's life. So, his worry is that in the next hundred years, which is a long time but it's a short time when lifespans are expanding and we have direct worries about our children and grandchildren--over the next hundred years we could hit 700. Seven hundred could--I think he suggests there's a 10% chance that could lead to 6 degrees of warming. You are suggesting that's just not possible, given the relationship between carbon dioxide concentration and temperatures that we've observed in the past. Now, the question would be--so, one, I want you to verify that they've got that right. And then, two, the question would be: It is possible that there are other things going on; that the reason we've only seen this small of warming we've had so far is because of sun spot activity, volcanic activity, ocean changes--who knows? What do we know about any of that? Guest: Yeah. Well, you are quite right. There are huge uncertainties. We don't know about all of that. And one of the frustrations has been these recent papers saying things like 'All the warming has gone into the ocean,' and then instead of that being a guess, hypothesis, a preliminary discovery, it becomes, 'Oh, they've solved the problem.' And therefore, you know, etc. Premature consensus, premature certainty being declared the whole time in this debate. Which is very dangerous. But back to the main point about Martin Weitzman's fat tails: You describe his point very accurately. And it is a well-known argument that a small possibility of a very large disaster needs to be taken seriously. It's in a sense the same idea of the Black Swan argument, that Nassim Taleb puts forth-- Russ: And he says the same-- Guest: and I would argue that it actually--sorry. Russ: Taleb has made the same point about climate change. Guest: He has indeed. Russ: He's in the same camp. Guest: And I would argue that it's a new version of Pascal's Wager--if you remember, Blaise Pascal said, 'I don't think God exists, but if he does, I'm in much deeper trouble for not believing in him. Whereas if he doesn't it doesn't matter. Therefore, it pays to believe in him--[?]' Russ: Rather than take a chance. Guest: [?] Rather than take a chance. Russ: Eternal damnation is a big negative, so a few years of religious observance is a good investment. That's the argument. Guest: Correct. Exactly. And I think that's a slightly closer analogy than other people would think. In other words, I think there's an element of sort of religiousness in all of this. But, why do I think that Weitzman's approach in that respect is not the right way to think about it? Two reasons. One is empirical: that actually the fat tail on the distribution, the relatively significant even if small possibility of a really big warming has got a heck of a lot thinner in recent years. This is partly because there was a howling mistake in the 2007 IPCC Report, the AR4 Report (Fourth Assessment Report: Climate Change, 2007), where a graph was actually distorted. And a brilliant scientist named Nick Lewis pointed this out later. It's one of the great, shocking scandals of this, that a graph--and I'm literally talking about the shape of the tail of the graph--was distorted to make a fatter tail than is necessary. When you correct that, the number gets smaller. When you feed in all these 14 papers that I've been talking about, all the latest observational data, 42 scientists involved in publishing this stuff, most of the mainstream scientists--I'm not talking about skeptics here--when you feed all that in and you get the average probability density functions for climate sensitivity, they turn out to have much thinner tails than was portrayed in the 2007. And that Martin Weitzman is basing his argument on. So the 10% chance of 6 degrees of warming in 100 years becomes much less than 1% if you look at these charts now. So, we've got to update our knowledge based on our latest information. And after all, we've got 5 more years of data, and 5 more years of relatively slow warming, and 5 more years of knowledge about watching the past. And by the way, one of the excuses for lack of warming for the last 50 years has since been exploded. And that is the aerosol one. It used to be thought that we were dampening warming by putting so much sulfate into the air through the burning of coal. There is an effect there; but it turns out that now we know more about it, that effect is smaller than we thought. So, for all these reasons, the tail is very thin. The probability of really dramatic warming is extremely small indeed, now. It's been narrowed down. And that is acknowledged in the last IPCC report--not explicitly enough for my liking, but it is there. And it's got to the point where it's so thin that, in my view, it deserves no more attention than the small possibility that we will be hit by an asteroid. The small possibility there will be a catastrophic volcanic explosion. The small possibility that the measures we're taking against climate change, including renewable energy and preventing people getting hold of fossil fuels and things like that, will itself be very dangerous. All these things could be dangerous. I mean, aliens could arrive, even take over the planet. Should we spend a lot of money now to try and prevent that possibility? You have to, at some point, take a reasonable view that certain possibilities are too small to spend a fortune on. Russ: Well, some would argue that if aliens attack the planet, it would stimulate the economy as we prepare for it. But I will leave that to another episode.
Quark Soup by David Appell
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