Stuck in the 20th century at #Ozfail

I really need to get back to the analysis of tax and expenditure options I’ve been working on, but the absurdities of the Oz keep distracting me. Today’s paper runs a front page story claiming “Temperatures were higher 2000 years ago“. The story is based on a study published in Global and Planetary Change, which uses tree ring records to estimate (with lots of caveats about uncertainty) that Northern Hemisphere (presumably land) temperatures were warmer in the 1st Century AD than in the 20th. More precisely, “The first century AD was the warmest 100-year period (+0.60C on average relative to the 1951-1980 mean) of the common era”. Take that, warmists!

There’s are a couple of minor problems with the story. As part of the Murdoch empire, encompassing 20th Century Fox, the Oz has apparently not noticed that the 20th century ended some years ago. And, being prone to printing silliness about pauses in warming, the writer, Graham Lloyd, did not bother to check whether the temperature today is warmer than the 1951-1980 mean. This isn’t hard to do. The US National Climatic Data Center reports global temperatures on a monthly basis. It reports that the Northern Hemisphere land temperature for September 2012 was +1.04 ± 0.26 above the 20th century average (I’ve checked and 1950-80 was about equal to the average for C20 as a whole).

So, the correct headline for the story should have been “Northern Hemisphere warmer than at any time in past 2000 years”

One more point, just for completeness. Readers might reasonably assume that the graphic accompanying the story is taken from the journal article it reports. In fact, it’s credited to the Global Warming Policy Foundation – given the fact that the Oz has linked to it, you don’t need to be Einstein to guess what kind of policies the scientific ex this foundation (headed by Benny Peiser) is pushing.

Update Reader andrewt points us to the actual article. The GWPF graphic is taken from the article, with the addition of a bunch of chartjunk. The article actually focuses on Northern Scandinavia, though its results are broadly consistent with other reconstructions at the hemispheric and global scale. And, while I won’t bother linking, it’s clear that Lloyd has taken his story, and interpretation of the results, from the Anthony Watts “sceptic” site.

Statistical significance

I know I should just ignore the Oz, but faced with its continuous campaign to promote innumeracy, cheered on by the likes of Alan Jones and Andrew Bolt, I can’t help but try to set things straight. We’ve seen on many occasions that nearly all “sceptics” either misrepresent of misunderstand the concept of statistical significance, assuming it to correspond to the ordinary meaning of “significant”. The classic example is the Lindzen talking point, made in 2008 that “there has been no statistically significant warming since 1995”. As everyone who understands statistical signifance (notably including Phil Jones, who gave an accurate response and saw a distorted version of his words become a delusionist meme), that’s because statistical significance depends on sample size. Roughly speaking, to see a significant upward trend in a noisy time series, the trend, multiplied by the number of years of data, needs to be about twice the standard deviation of the random variation about trend. So, if you have an upward trend of 0.015 degrees per year, and a standard deviation of 0.1 (these are estimates, but feel free to check)) you typically need 14 or 15 years of data to see a statistically significant trend. Over shorter periods, it’s easy to eyeball a pause or decline, as this graph from Skeptical Science shows.

Lindzen obviously knew this, and it was easy to check that he could go back 13 years from 2008 (but no further) without finding a statistically significant trend. He also knew that, given a few more years of data, the trend for the period since 1995 would be statistically significant, but correctly assumed that no-one on the delusionist side would know or care. Now, the Oz has this, from Michael Asten, professor of geophysics at Monash University. It’s worded carefully enough for me to think he knows he’s pulling the same swifty as Lindzen, but it’s hard to tell for sure[1]

Global temperatures have not increased in a statistically significant sense in the past 15 years. A pause of 10 years in the upward trend of the past 40 years would be unsurprising from existing models. A pause of 20 years would definitely surprise. Changes across the next five years will be watched closely.

As you would expect, Asten has to move Lindzen’s goalposts forward by a couple of years, to an implied starting date of 1997. Note also that he slides from “no statistically significant trend” to “a pause”. What can we say about this? In one sense he is right. As I’ve said, we need about 15 years of data to get a statistically significant trend, so we wouldn’t expect to find one with 10 years, and we would usually expect to find one with 20 years. But, of course, that number itself is variable. Asten is repeating basic facts about time series, in a way that would lead unwary or gullible readers (the vast majority, given the outlet) to suppose that recent evidence casts doubt on the observed warming trend. The only thing that’s hard to figure here is whether he is fooling himself as well as his readers.

fn1. (Lindzen himself often slipped from “no statistically significant warming” to “no warming” either out of sloppiness or because he thought no one was looking.

Jones goes to J-school

The past seems to be catching up with Alan Jones, just when his most recent outrage has caused him more trouble than all the others put together. First, he lost an appeal against a finding that he incited racial hatred in the leadup to the Cronulla riots. Then 2GB got caught in another cash-for-comment scandal. Now he’s been told to go back to journalism school, to learn about checking his facts, in relation to his silly claim that ”The percentage of man-made carbon dioxide Australia produces is 1 per cent of .001 per cent of carbon dioxide in the air.” (Similar claims have been made by Andrew Bolt, and by some commenters at this blog.) As Lenore Taylor observes, if 2GB and Jones really want to check their facts, they’ll have a lot of work ahead of them.

The Oz is not a newspaper

I happened to look at the front page of The Australian today, something I don’t do very often. Of five front-page stories, one was a brief teaser for a business story about Channel 9. The other four were hit pieces on the Federal government. Even a piece on increasing inequality was presented as an attack on Wayne Swan. One (on asylum seekers) was accompanied by an “opinion” piece by Greg Sheridan, notable for the fact that it was more sober and balance than the “news” story on which Sheridan was commenting.

As I’ve said before, I don’t see this as a problem requiring a regulatory solution, as suggested by the Finkelstein Report. Rather, we simply need to recognise that 20th century assumptions about “the press” have ceased to be applicable. The Australian looks like a 20th century newspaper, just as Fox resembles a 20th century US TV network, but both are far more like political blogs in terms of their content and operating procedures.

An obvious implication is that, while Murdoch should be free to publish whatever he likes, his employees should not be accorded any of the special privileges that were routinely accorded to journalists in the 20th century, such as press passes, access to press conferences, special privileges shielding sources and so on. These should either be made available to everyone, or restricted to media organizations willing to commit to factual reporting, fair treatment of the issues in news stories and so on.

The most important asset of the traditional media is not a formal privilege but the assumption that journalists, unlike you and me, have a right to ask questions of perfect strangers on matters of all kinds, and to expect an answer. In a context where the answer is bound to be used dishonestly, this makes no sense.

If I were advising the government at this point, I would suggest a routine policy of “no comment” in response to any question from an employee of News Limited. Obama tried this with Fox News early on, but other news organizations threatened to boycott his press conferences in solidarity and he backed down. That was, I think, a mistake.

Technical problems

The Ozblogistan network suffered either an internal breakdown or a DDOS attack last night. Things seem to be OK now, but if you are having trouble getting access you may need to refresh your cache etc. Also the site will be down (hopefully only a couple of minutes), around 6pm Brisbane time.