A Heretic on Global Warming

Freeman Dyson is always worth listening to. In this article, he discusses what is and isn't science, the need for heretics, and, of course, global warming.

Over on Jerry Pournelle's Mail page, a reader sent in a link to an article on the difficulty in even defining Surface Air Temperature. There is more variation between the different ways of calculating the magic number than the total warming they are supposed to be measuring. Jerry's response pretty much reflects my personal views:

The referenced articles are certainly worth reading for anyone interested in "Human Global Warming", but they don't tell us much. The FAQ at Goddard (responsible official, James Hansen) admits that there is no standard "surface temperature" and gives no formal definition. This alone ought to be enough to cause us to reject the alarm warnings: they can't or won't tell us how they get the numbers they scare us with. They're sure they see Global Warming, but they can't tell us what the temperature is, or what it was on December 31 last year, or what it was three weeks ago. And more to the point, they have no precise -- within a couple of degrees -- measure of the Global Temperature as of 1900, or 2000, so when they tell us how much it has risen since some date certain, we don't really know what they are saying.

The fact is that you can get almost any trend you want from the data, and you can get a "Mean Surface Temperature" from any of a dozen methods -- and those will vary by considerably more than the projected "warming."

Does this mean the Earth is NOT warming? Of course not. We can be darned certain that the mean Earth temperature is higher today than it was in 1776. We can be certain that it was warmer in 1900 than it was in 1776. What we can't be certain of is this: is (Mean Temperature 1900 minus Mean Temperature 1776) greater or less than (Mean Temperature 2000 minus Mean Temperature 1900)? Or to put it another way, when did the obvious rise in temperature between 1776 and 2000 take place? Recently? In the 1800's? Between 1900 and 1950?

Once again, I welcome communication from those who tell us that the Earth is warming and it's human activity that's doing it; but rather than proof by repeated assertion, what I'd like to know is on what data they base their conclusions? And how do they obtain that data? Just what is the formal definition of the "Mean Annual Temperature"? What do we mean when we say that 1938 was warmer (or cooler) than 1998? And by that I mean: what operations were performed to obtain the two numbers? What data did you average and with what weights? Do you take a daily world temperature, add all those up, and divide by 365? And given that you do, how do you get the mean daily temperature? Do you take temperatures of sea surface, air at sea surface, land at surface, air at surface level, air ten meters above surface, weight each by the amount of surface area on the globe it represents (one assumes that there are fewer temperatures taken at the South Pole and McMurdo and the Ross shelf to represent Antarctica than are taken in the continental US), and average all that?

It's odd, but so far I can't find how it's done. Moreover, apparently Hansen doesn't tell people -- which is why McKintire had to reverse engineer the data, and thus discover the Y2K bug.

When I took Philosophy of Science from Gustav Bergmann, I was taught that one definition of science is this: you can write a letter to a colleague, describing how you got a result, and he can, following your description of the experiment, obtain the same results. If you don't tell people how you got your results it isn't science.

Now true, Bergmann was one of the last survivors of the Vienna Circle, and the Weiner Kreiss was deeply committed to what is called "operational philosophy", which is a fairly extreme empiricism; but that doesn't make Bergmann wrong. If Hansen and the Human Global Warming advocates -- who go so far as to group "Global Warming Deniers" with "Holocaust Deniers" and presumably would treat Global Warming Deniers as Holocaust Deniers are treated in Europe, namely jailed -- have a different definition of science that says they don't have to tell people how they got their results, surely they have some obligation to tell the public -- which funds their activities and on whose backs the costs of their "remedies" will fall -- just what they are doing?

How do we get an annual Global Temperature? I still can't find the answer to that. And the Goddard paper http://data.giss.nasa.gov/gistemp/abs_temp.html says, to me at least, that they don't really have a formal definition, and raises many of the same questions I do.

And I'm fairly certain given the current cover on Newsweek that there is a vocal minority that would love to see "Global Warming Deniers" persecuted... er... prosecuted and imprisoned.