What’s wrong with the Climate debate – Brad DeLong
You want to see how not to debate, look no further than DeLong.
Russ Roberts knows as well as I do–as well as anybody who has taken even one semester of statistics does–that “no trend” does not mean the same thing as “no statistically significant trend,” that you are unlikely to find statistical significance when you restrict your attention to a short period because your statistical tests then lack power, and that everyone literate in statistics asked for their point estimate of the warming trend since 1975 would say that it is almost as much as the overall trend since 1860: 0.012C per year as compared to 0.015C per year.
Russ Roberts knows all this. But he hopes to trick some of his readers by hiding it.
Lyingest economist alive…
Now look at the comments. All full of vitriol and hubris. One problem, which I’m quilty of, is linking the Daily Mail instead of the BBC, although the Daily Mail article was up before the BBC interview.
BC: Do you agree that from 1995 to the present there has been no statistically-significant global warming?
Phil Jones: Yes, but only just. I also calculated the trend for the period 1995 to 2009. This trend (0.12C per decade) is positive, but not significant at the 95% significance level. The positive trend is quite close to the significance level. Achieving statistical significance in scientific terms is much more likely for longer periods, and much less likely for shorter periods…
The quip is over statistical significance. The problem here is data points. 15 years doesn’t give enough data points. You need at least 30 to give even a semblance of statistical relevance. It all depends on when you start.
Now the point of this is not to discuss the data, more of the tone. Notice the language DeLong uses, he calls Dr. Roberts the “Lyingest economist alive.” Which is some charge considering the Krugman is still alive, but I digress. (And yes I know I’m being a partial hypocrite here)
And of course notice how Brad hones in to the word “trend” instead of the implications of the small trend. The implications, considering carbon emissions have steadily been going up, don’t look good for the carbon/warming link. Which is what I’ve been trying to say for a long time. There’s been warming, but not a lot of evidence to suggest that it’s all man’s fault. DeLong knows that, that’s why he doesn’t want to discuss that part, so instead he resorts to name calling.
I’ll finish by saying, the graphs are from “expert” sources; CRU, IPCC assessment and NOAA. So I hope no one can say I’m cherry picking…although I know that will come up anyway.