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The Climate-Change Answer

Disclaimer: This page is the opinion of Steven Stoft, and it may not be shared by others associated with the GEP Center.

Non-scientist cannot determine the reliability of climate science simply by understanding the science. At least, that seems to be the case after a few months of research. This is not always the case with science. When scientists say they have figured out that an atom's nucleus is made of protons and neutrons, we can't check their experiments, but when they explode an A-bomb, we can be quite sure they've got it figured out. But there does not seem to be any such clear evidence available for climate science. James Hansen comes closest to explaining evidence we can check, but he has not tied up a number of loose ends, so I still see no clear evidence.

What to Do if We Cannot Judge the Science on its Merits?

There are many areas of science, where this is the case, and the we must rely on the scientific community. So here is my best reading of what they are saying and how reliable they are in this area.

The UN's IPCC says that there is a 90 percent chance that half or more of the temperature increase since 1950 is man made. That means there is a 10 percent chance that more than half is caused by nature, in which case their projections of temperature increases would be only half (or less) than the best estimates they present.

In other words, they say there's about a 10 percent chance business as usual will be only bad not horrible.

I see two reasons to think this estimate is biased. (1) They need a high level of agreement to say anything at all, so skeptics have some veto power. This would make the estimate conservative. (2) As Feynman showed, experimental scientist do succumb to group think. He tracked the estimates of one famous physical constant. There was no reason for any particular experiment to come out high or low, but once the first one was wrong, each subsequent experiment corrected it only a bit, so every one was off in the same direction. Group think would make the reported level of certainty too high.

This leaves us with a very rough estimate that there's a 90 percent chance were in deep trouble.

My Personal Guesstimate

I know enough statistics to be sure that the statistics associated with climate models -- the statistics that determine their accuracy -- are often wrong. I have also seen problems with big models up close. I vote with Jim Hansen on this. The big models tell us less than they seem to. Hansen's approach may say more, but some pieces are still not within my grasp. So I feel considerably less certain than the scientists claim to be.

I also know of cases where the scientific consensus has been wrong for decades: (1) The claim that brain cells don't reproduce, (2) that ulcers are not caused by bacteria. There's a third one having to do with curing allergies to bee stings and I'm sure there are more I don't know about.

So my personal view remains that there's a 50/50 chance climate change since 1950 has been half caused by humans. That means I think it is probably not as bad as the IPCC estimates, but there is still something like a 20 percent chance that it is that bad or worse.

So What Should We Do?

This is the easy question. With a 1/2 of 1 percent change that my house will catch fire (not burn down) I buy fire insurance. And so does everyone else. With a 20 percent chance that the earth is in real danger I say we buy climate insurance. I can repair my house or buy another. But many of the changes that would happen to the Earth are irreversible. Moreover, we could do far more than we are now doing for a cost of 1/4 of 1 percent of our income (see Global Carbon Pricing).

At a minimum, no matter how skeptical you are, we should put in place a framework -- for example a low-level global carbon tax -- that can be ramped up quickly if we get bad news. Given that we've made almost no progress getting organized over the last 15 years, one things seems certain. We will not move too far too fast. If we organize and act as fast as possible, that will still be very slow -- too slow if it turns out we are in trouble, as is fairly likely.

This is not a call for frivolous action, such as subsidies for solar roofs. I am suggesting we organize an efficient mechanism that can do a lot cost effectively as soon as the need becomes obvious to enough people.