A surreal scientific blunder last week raised a huge question mark about the temperature records that underpin the worldwide alarm over global warming. On Monday, Nasa's Goddard Institute for Space Studies (GISS), which is run by Al Gore's chief scientific ally, Dr James Hansen, and is one of four bodies responsible for monitoring global temperatures, announced that last month was the hottest October on record.
Snow in London A sudden cold snap brought snow to London in October
This was startling. Across the world there were reports of unseasonal snow and plummeting temperatures last month, from the American Great Plains to China, and from the Alps to New Zealand. China's official news agency reported that Tibet had suffered its "worst snowstorm ever". In the US, the National Oceanic and Atmospheric Administration registered 63 local snowfall records and 115 lowest-ever temperatures for the month, and ranked it as only the 70th-warmest October in 114 years.
So what explained the anomaly? GISS's computerised temperature maps seemed to show readings across a large part of Russia had been up to 10 degrees higher than normal. But when expert readers of the two leading warming-sceptic blogs, Watts Up With That and Climate Audit, began detailed analysis of the GISS data they made an astonishing discovery. The reason for the freak figures was that scores of temperature records from Russia and elsewhere were not based on October readings at all. Figures from the previous month had simply been carried over and repeated two months running.
The error was so glaring that when it was reported on the two blogs - run by the US meteorologist Anthony Watts and Steve McIntyre, the Canadian computer analyst who won fame for his expert debunking of the notorious "hockey stick" graph - GISS began hastily revising its figures. This only made the confusion worse because, to compensate for the lowered temperatures in Russia, GISS claimed to have discovered a new "hotspot" in the Arctic - in a month when satellite images were showing Arctic sea-ice recovering so fast from its summer melt that three weeks ago it was 30 per cent more extensive than at the same time last year.
A GISS spokesman lamely explained that the reason for the error in the Russian figures was that they were obtained from another body, and that GISS did not have resources to exercise proper quality control over the data it was supplied with. This is an astonishing admission: the figures published by Dr Hansen's institute are not only one of the four data sets that the UN's Intergovernmental Panel on Climate Change (IPCC) relies on to promote its case for global warming, but they are the most widely quoted, since they consistently show higher temperatures than the others.
If there is one scientist more responsible than any other for the alarm over global warming it is Dr Hansen, who set the whole scare in train back in 1988 with his testimony to a US Senate committee chaired by Al Gore. Again and again, Dr Hansen has been to the fore in making extreme claims over the dangers of climate change. (He was recently in the news here for supporting the Greenpeace activists acquitted of criminally damaging a coal-fired power station in Kent, on the grounds that the harm done to the planet by a new power station would far outweigh any damage they had done themselves.)
Yet last week's latest episode is far from the first time Dr Hansen's methodology has been called in question. In 2007 he was forced by Mr Watts and Mr McIntyre to revise his published figures for US surface temperatures, to show that the hottest decade of the 20th century was not the 1990s, as he had claimed, but the 1930s.
Another of his close allies is Dr Rajendra Pachauri, chairman of the IPCC, who recently startled a university audience in Australia by claiming that global temperatures have recently been rising "very much faster" than ever, in front of a graph showing them rising sharply in the past decade. In fact, as many of his audience were aware, they have not been rising in recent years and since 2007 have dropped.
Dr Pachauri, a former railway engineer with no qualifications in climate science, may believe what Dr Hansen tells him. But whether, on the basis of such evidence, it is wise for the world's governments to embark on some of the most costly economic measures ever proposed, to remedy a problem which may actually not exist, is a question which should give us all pause for thought.
As many people will have read there was a glitch in the surface temperature record reporting for October. For many Russian stations (and some others), September temperatures were apparently copied over into October, giving an erroneous positive anomaly. The error appears to have been made somewhere between the reporting by the National Weather Services and NOAA's collation of the GHCN database. GISS, which produces one of the more visible analyses of this raw data, processed the input data as normal and ended up with an October anomaly that was too high. That analysis has now been pulled (in under 24 hours) while they await a correction of input data from NOAA (Update: now (partially) completed).
There were 90 stations for which October numbers equalled September numbers in the corrupted GHCN file for 2008 (out of 908). This compares with an average of about 16 stations each year in the last decade (some earlier years have bigger counts, but none as big as this month, and are much less as a percentage of stations). These other cases seem to be mostly legitimate tropical stations where there isn't much of a seasonal cycle. That makes it a little tricky to automatically scan for this problem, but putting in a check for the total number or percentage is probably sensible going forward.
It's clearly true that the more eyes there are looking, the faster errors get noticed and fixed. The cottage industry that has sprung up to examine the daily sea ice numbers or the monthly analyses of surface and satellite temperatures, has certainly increased the number of eyes and that is generally for the good. Whether it's a discovery of an odd shift in the annual cycle in the UAH MSU-LT data, or this flub in the GHCN data, or the USHCN/GHCN merge issue last year, the extra attention has led to improvements in many products. Nothing of any consequence has changed in terms of our understanding of climate change, but a few more i's have been dotted and t's crossed.
But unlike in other fields of citizen-science (astronomy or phenology spring to mind), the motivation for the temperature observers is heavily weighted towards wanting to find something wrong. As we discussed last year, there is a strong yearning among some to want to wake up tomorrow and find that the globe hasn't been warming, that the sea ice hasn't melted, that the glaciers have not receded and that indeed, CO2 is not a greenhouse gas. Thus when mistakes occur (and with science being a human endeavour, they always will) the exuberance of the response can be breathtaking - and quite telling.
A few examples from the comments at Watt's blog will suffice to give you a flavour of the conspiratorial thinking: "I believe they had two sets of data: One would be released if Republicans won, and another if Democrats won.", "could this be a sneaky way to set up the BO presidency with an urgent need to regulate CO2?", "There are a great many of us who will under no circumstance allow the oppression of government rule to pervade over our freedom—-PERIOD!!!!!!" (exclamation marks reduced enormously), "these people are blinded by their own bias", "this sort of scientific fraud", "Climate science on the warmer side has degenerated to competitive lying", etc… (To be fair, there were people who made sensible comments as well).
The amount of simply made up stuff is also impressive - the GISS press release declaring the October the 'warmest ever'? Imaginary (GISS only puts out press releases on the temperature analysis at the end of the year). The headlines trumpeting this result? Non-existent. One clearly sees the relief that finally the grand conspiracy has been rumbled, that the mainstream media will get it's comeuppance, and that surely now, the powers that be will listen to those voices that had been crying in the wilderness.
Alas! none of this will come to pass. In this case, someone's programming error will be fixed and nothing will change except for the reporting of a single month's anomaly. No heads will roll, no congressional investigations will be launched, no politicians (with one possible exception) will take note. This will undoubtedly be disappointing to many, but they should comfort themselves with the thought that the chances of this error happening again has now been diminished. Which is good, right?
In contrast to this molehill, there is an excellent story about how the scientific community really deals with serious mismatches between theory, models and data. That piece concerns the 'ocean cooling' story that was all the rage a year or two ago. An initial analysis of a new data source (the Argo float network) had revealed a dramatic short term cooling of the oceans over only 3 years. The problem was that this didn't match the sea level data, nor theoretical expectations. Nonetheless, the paper was published (somewhat undermining claims that the peer-review system is irretrievably biased) to great acclaim in sections of the blogosphere, and to more muted puzzlement elsewhere. With the community's attention focused on this issue, it wasn't however long before problems turned up in the Argo floats themselves, but also in some of the other measurement devices - particularly XBTs. It took a couple of years for these things to fully work themselves out, but the most recent analyses show far fewer of the artifacts that had plagued the ocean heat content analyses in the past. A classic example in fact, of science moving forward on the back of apparent mismatches. Unfortunately, the resolution ended up favoring the models over the initial data reports, and so the whole story is horribly disappointing to some.
Which brings me to my last point, the role of models. It is clear that many of the temperature watchers are doing so in order to show that the IPCC-class models are wrong in their projections. However, the direct approach of downloading those models, running them and looking for flaws is clearly either too onerous or too boring. Even downloading the output (from here or here) is eschewed in favour of firing off Freedom of Information Act requests for data already publicly available - very odd. For another example, despite a few comments about the lack of sufficient comments in the GISS ModelE code (a complaint I also often make), I am unaware of anyone actually independently finding any errors in the publicly available Feb 2004 version (and I know there are a few). Instead, the anti-model crowd focuses on the minor issues that crop up every now and again in real-time data processing hoping that, by proxy, they'll find a problem with the models.