Next to the much-(and usually falsely)-maligned hockey stick graph, one of the denier community’s favorite targets has been a series of climate modeling graphs that NASA‘s James Hansen produced in 1988.
Notwithstanding that Hansen has done two more decades of world-leading research, people like Stephen McIntyre of the quibbler site ClimateAudit.Org have obsessed endlessly about the purported “flaws” in that graph series.
Which is why it’s so surprising to see McIntyre accepting Hansen’s work now.
The thrust of the criticism of this much-dated modeling is that Hansen graphed three potential climate trajectories, two of which appeared to be decidedly above the ACTUAL trajectory of average temperatures mapped during the model period.
Certainly, if you click on McIntyre’s most recent post, you see that Hansen’s A and B scenarios are riding high. (Although, you will also notice that the trend lines are tracking in a worrying parallel.) You will further notice that McIntyre has picked the annual low point of a graph that goes up and down EVERY YEAR to try to argue that average temperature is currently below even Hansen’s most modest prediction. That’s a cheap trick, unworthy of a decent statistician.
But then McIntyre says:
“… the uncertainties in the trend are much wider than sometimes thought and are sufficiently wide that neither Hansen’s Scenario B (nor scenarios with lesser and greater “true” increases) can be said to be rejected.”
In English, McIntyre appears to be saying that when temperatures swing as wildly as these ones do, you have to build in a margin of error. And if you accept a reasonable margin of error, you have to accept two of Hansen’s three scenarios as also being reasonable.
McIntyre deserves some credit for this acknowledgment. Although he has made himself a tool of the denier community, fixing on statistical errors or controversial interpretations which other people have then used to undermine faith in the whole theory of anthropogenic global warming, he seems in this instance to be valuing his own credibility as a statistician above his alliances to the denier community.
So, Steve: Bravo! We’ll try to take you more seriously in the future.
