Who'd've Discredited It?

'Case against climate change discredited by study' shrieked the Independent yesterday. That must be one hell of a study. Except that it isn't:

A difference in the way British and American ships measured the temperature of the ocean during the 1940s may explain why the world appeared to undergo a period of sudden cooling immediately after the Second World War.

Scientists believe they can now explain an anomaly in the global temperature record for the twentieth century, which has been used by climate change sceptics to undermine the link between rising temperatures and increases in atmospheric carbon dioxide.

Not only does the study (published this week in Nature) not claim to discredit what the Independent's headline claims it discredits, but it doesn't even discredit what the scientists behind the study claim it discredits. Moreover, what the scientists claim their work does discredit was, according to prominent Environmentalists, discredited years ago. And finally, what everybody seems to be trying to discredit isn't even something that sceptics seem to be crediting in the first place.

Yes, sceptics are concerned about the post-war temperature slump, but not because of the sudden steep drop around 1945; it is the downward trend in temperatures between about 1945 and 1975 that they suggest needs explaining (which is actually longer than the upward trend between 1975 and 1998, just so you know), given that greenhouse gas emissions were rising throughout that period.

And as the graph used by the Independent to bolster its case (supplied by CRU, apparently) demonstrates, the Nature study does absolutely nothing to address that concern:



In fact, the most striking thing about the graph is that, once the sampling errors identified by the study have been taken into account, the period of warming in the latter half of the twentieth century was shorter than previously thought, and that the '45-'75 temperature slump is more pronounced.

According to Phil Jones, a co-author of the paper, the study

lends support to the idea that a period of global cooling occurred later during the mid-twentieth century as a result of sulphate aerosols being released during the 1950s with the rise of industrial output. These sulphates tended to cut sunlight, counteracting global warming caused by rising carbon dioxide.

"This finding supports the sulphates argument, because it was bit hard to explain how they could cause the period of cooling from 1945, when industrial production was still relatively low," Professor Jones said.

That might be so. But the aerosols issue is supposed to have been done and dusted long ago. One of the central criticisms aimed at the infamous Great Global Warming Swindle, for example, is precisely that it failed to entertain the idea that the post-1940 decline in global temperatures was the result of increases in sulphurous emissions that masked the forcing effect of rising atmospheric CO2. George Monbiot described the omission as 'straightforward scientific dishonesty'. After all, he said, that 'temperatures declined after the Second World War as a result of sulphate pollution from heavy industry, causing global dimming...is well-known to all climate scientists.' And as we have reported before, this was also one of the main points raised by the Royal Society's Bob Ward and 36 scientific experts in their open letter to Swindle producer Martin Durkin.

And yet, as we've reported elsewhere, other experts in the field just don't agree. UC San Diego atmospheric physicist Veerabhadran Ramanathan, for example, told us that the empirical evidence for the sulphate masking of warming is 'pretty flimsy'. We do not doubt that the Nature study is an important contribution to the field. (Although it's interesting that Steve McIntyre seems to have produced a similar analysis more than a year ago.) What we do doubt is that the headlines, soundbites, and wild interpretations from newspapers and scientists alike bear much relevance to what is a dry, technical, scientific study, which, while increasing our ability to understand and predict climate trends, says little in itself about the truth or otherwise of global warming.

That said, the BBC's Richard Black has demonstrated uncharacteristic reserve in his coverage of the paper, which includes the following quote from CRU's Mike Hulme:

Corrections for this measurement switch have not yet been applied to produce a new graph of 20th Century temperatures - that work is ongoing at the UK Met Office - but as the land temperature record shows a flattening of the upwards trend from the 1940s to the 1970s, clearly something did change around the 1940s to ameliorate the warming.

"It perhaps suggests that the role of sulphate aerosols, that cooling effect, was less powerful than we thought," said Mike Hulme from the University of East Anglia (UEA), who was not involved in the study.

George Monbiot and the Royal Society are just plain wrong - the science is plainly not 'settled'. And so is Steve Connor, the author of the Independent article. As he wrote last year in response to the Swindle:

The programme failed to point out that scientists had now explained the period of "global cooling" between 1940 and 1970. It was caused by industrial emissions of sulphate pollutants, which tend to reflect sunlight. Subsequent clean-air laws have cleared up some of this pollution, revealing the true scale of global warming - a point that the film failed to mention.

'Scientists' have 'explained' nothing of the sort. As this case shows, the science is not settled. Indeed science is never settled. It is constantly re-evaluating what it understands about absolutely everything. And that's especially crucial to bear in mind when the science in question has been bestowed with the kind of political significance that climate science has. To claim otherwise is to do a disservice to both science and politics. It reduces science to a flimsy fig leaf used simply to hide the embarrassing inadequacies of the latest political fad; and it reduces politics to an aimless exercise in number-crunching.

Dessler's Grist to the Sceptics' Mill

On Gristmill, Andrew Dessler provides us with an excuse for a self-indulgent recap:

I was at a meeting earlier this week and was talking to one of the coordinating lead authors of the recent IPCC working group 1 report on the physical science of climate change. He remarked that he was quite surprised that how little substantive criticism the IPCC Fourth Assessment Report had received since its release just about one year ago.

Reflecting on why this might be the case, he says:

the scientists writing the report knew that the denial machine would go over the report with a fine tooth comb looking for any "gotcha" mistakes to use to discredit the IPCC. Because of that, the IPCC report was extremely carefully worded so as to make virtually every statement in the report bulletproof.

That may be so. But as we've reported before, the 'denial machine' is way behind the warmers - media, politicians and the IPCC itself - when it comes to misrepresenting what the IPCC reports have to say. Writing about AR4, for example, the BBC's Richard Black claimed that 'The IPCC states that climate change is "unequivocal" and may bring "abrupt and irreversible' impacts"'. When we looked at the report, however, it was clear that Black had simply taken words from the report and reassembled them to mean something entirely different. The report itself only used the word 'abrupt' once: 'The MOC is very unlikely to undergo a large abrupt transition during the 21st century'. 'Very unlikely' becomes 'may'.

The 'irreversible impacts' part is just as tenuous. According to the report:

Climate change is likely to lead to some irreversible impacts. There is medium confidence that approximately 20-30% of species assessed so far are likely to be at increased risk if increases in global average warming exceed 1.5-2.5oC (relative to 1980-1999). As global average temperature increase exceeds about 3.5oC, model projections suggest significant extinctions (40-70% of species assessed) around the globe.

But as we said at the time:

likely... some... medium confidence... approximately... 20-30% of species assessed so far... likely... increased risk... if... Of how many 'assessed species', exactly?

But such caveats and unknowns don't stop the BBC hack using the word 'irreversible' to sex up an article that would have otherwise been "IPCC report marginally less alarmist than last time, yet doesn't say anything all that new".

Likewise, IPCC Chair Rajendra Pachauri can't resist the temptation to extravagate the IPCC's findings beyond recognition, for dramatic (comic?) effect.

We picked up on Andrew Dessler's argument last year that the earth was like a sick child, which needed the attention of the equivalent of specialist pediatric doctors - the IPCC - rather than engage with any of the ideas put forward by sceptics. 'So given the critical nature of the climate change problem, who should we listen to?' he wondered.

My opinion, and the opinion of all the governments of the world, is that we should listen to people who specialize in climate science. That's the IPCC.

Following that, our survey of the contributing authors to the IPCC AR4 reports showed that most weren't climate scientists, as he had argued. Many, in fact, were precisely the social scientists, computer scientists, and economists he believed should be excluded from the debate.

In his latest contribution, Dessler goes on to say:

In fact, it is quite amazing to me that essentially none of the IPCC documents produced over the last 18 years has been found to contain any substantive errors.

He obviously has not been listening to climate catastrophist and IPPC author James Hansen, who said in New Scientist last year:

I find it almost inconceivable that "business as usual" climate change will not result in a rise in sea level measured in metres within a century. Am I the only scientist who thinks so?

And has he forgotten the controversy caused by the use of the "Hockey Stick" graph, invented by Micheal Mann, who also happened to be lead author on the IPCC working group which made it famous? (Roughly equivalent to a researcher "peer-reviewing" his own work).

With all this in mind, Dessler goes on to say:

The trolls, of course, will come out with their litany of "errors" that the IPCC contains (I suspect a few will appear in the comments to this post), but when you look closely, the trolls are almost always misrepresenting the IPCC's statements.

In fact, that's the most common attack on the IPCC: make the claim that the IPCC said something ridiculous (which it didn't actually say), then disprove that ridiculous statement, and then use that as evidence that the IPCC's reports cannot be trusted. "The IPCC says that 2 + 2 = 5, but that's just hogwash. We know that 2 + 2 = 4. Thus, climate change is a hoax." Yeah, right.

But Dessler is doing the trolls' work for them. It's just that he is only sensitive to the misrepresentation of the IPCC in one direction. It is even funnier that he himself misrepresents the IPCC. One of the people doing the best job of discrediting the IPCC in the world right now is Andrew Dessler himself. May he keep up the good work.

Climate Change Rhetoric Worse Than Previously Thought

In case you hadn't noticed, the IPCC released its AR4 Synthesis Report, Summary for Policymakers on Saturday.

'Today the world's scientists have spoken clearly and with one voice,' said United Nations Secretary General Ban Ki-moon.

The BBC reported the event on Friday (R4 news 18:00), before the report was published...

HARRABIN: They're haggard with lack of sleep, but beaming that they've reached an agreement on an unequivocal message to politicians that climate change is real, dangerous, but manageable if steps are taken now. The results are compromised as usual, some wanted the final wording softer, others more strident still, but I'm told the final document when it's published tomorrow will be impossible to ignore. It'll say that we can see climate change happening already, sometimes, like in the Arctic, much faster than scientists predicted previously. We're likely to have more droughts, floods, oppressive heatwaves and species extinctions, it'll say, and some changes will be irreversible. That last phrase is so strong that some countries wanted it left out, but according to Steffan Zinger of WWF, they were voted down.

ZINGER: The word irreversible for instance was strongly debated and strongly questioned by certain governments which are on the other side of the Atlantic. But they in the end gave in and accepted that climate change will have irreversible consequences.

So that's how the 'science' that is supposed to inform the political process is achieved... Everybody stays up late, and argues until somebody 'gives in', or is 'voted down'. Some kind of 'speaking clearly and with one voice'.

Despite the headlines and column inches, there is virtually nothing new in this report. It's a rehash of the three reports published earlier this year by the IPCC. All that is new in the report itself (and which most news outlets chose to lead with) is the word 'irreversible'. Writing on the BBC website, for example, environment correspondent Richard Black tells us that 'The IPCC states that climate change is 'unequivocal' and may bring 'abrupt and irreversible' impacts'. But the only mention of these words in the IPCC report are in the section 'Anthropogenic warming could lead to some impacts that are abrupt or irreversible, depending upon the rate and magnitude of the climate change', which reveals a far less frightening and urgent picture than such accounts suggests:

Partial loss of ice sheets on polar land could imply metres of sea level rise, major changes in coastlines and inundation of low-lying areas, with greatest effects in river deltas and low-lying islands. Such changes are projected to occur over millennial time scales, but more rapid sea level rise on century time scales cannot be excluded. {3.4}

Does that mean immediate sea-level rise can't be ruled in? 'We don't know' would have sufficed. Similarly...

Climate change is likely to lead to some irreversible impacts. There is medium confidence that approximately 20-30% of species assessed so far are likely to be at increased risk if increases in global average warming exceed 1.5-2.5oC (relative to 1980-1999). As global average temperature increase exceeds about 3.5oC, model projections suggest significant extinctions (40-70% of species assessed) around the globe.

It shouldn't come as a surprise to anybody that extinction is an irreversible process. The clue is in the word "extinct". And anyway: likely... some... medium confidence... approximately... 20-30% of species assessed so far... likely... increased risk... if... Of how many 'assessed species', exactly?

As for the 'abrupt' bit (which isn't new, in that it was in the Working Group II report published back in April), all we get is

Based on current model simulations, the meridional overturning circulation (MOC) of the Atlantic Ocean will very likely slow down during the 21st century; nevertheless temperatures over the Atlantic and Europe are projected to increase. The MOC is very unlikely to undergo a large abrupt transition during the 21st century. Longer-term MOC changes cannot be assessed with confidence. Impacts of large-scale and persistent changes in the MOC are likely to include changes in marine ecosystem productivity, fisheries, ocean CO2 uptake, oceanic oxygen concentrations and terrestrial vegetation. Changes in terrestrial and ocean CO2 uptake may feed back on the climate system.

Contrasting the report with statements in the press reveals very different pictures. Over the weekend, BBC Radio 4 was ending its news items on the report with: 'The mainstream message from the IPCC is that it's not too late - if we act now.' According to Black's article on BBC online: 'The panel's scientists say the reversal needs to come within a decade or so if the worst effects of global warming are to be avoided.' Trouble is, the report doesn't actually say that. Anywhere. At all. Whatsoever.

So what is going on here? It is true that Dr Pachauri said in the press conference that CO2 emissions need to peak and start declining by 2015. But Pachauri is not the IPCC. And as we've pointed out recently, his statements on this issue do not reflect the IPCC position. Meanwhile, journalists are happy to confound 'the consensus' with 'what Pachauri reckons' because that way they can say that 'things are worse than ever before'.

The only differences between this report (and the press coverage of it) and previous ones concern the language, not the science. That language is getting more abrupt, and the problem is becoming irreversible. And our models predict it to get worse than previously expected.

Model Muddle

A new study suggesting that Arctic ice is melting faster than IPCC forecasts has been reported by the BBC as evidence that the IPCC is too conservative.

Since 1979, the Arctic has been losing summer ice at about 9% per decade, but models on average produce a melting rate less than half that figure... The scientists suggest forecasts from the Intergovernmental Panel on Climate Change (IPCC) may be too cautious.

What the article does not consider is that this is also evidence that IPCC forecasts are not very good. It's not as if it's the first time that real-world data has been at odds with the computer models...

This is the third time in the last few months that studies have suggested the IPCC's latest major global climate analysis, the Fourth Assessment Report, is too conservative.

Here's a particularly odd section...

This is the opposite view from that put forward by many "climate sceptics", who view the whole field of computer modelling as deeply flawed

Is the latest real world data not evidence that computer modelling is indeed flawed?

Here's an odder one...

Because of the way it works, the IPCC is bound to be conservative, as it assesses in considerable depth research already in the public domain. This process takes time, and means the panel's conclusions will always lag behind the latest publications.

By using 'conservative', Richard Black presupposes that newer research will always be painting a bleaker picture than old. Given that hi tech climate models are having such trouble predicting the future, we seriously doubt his own ability to do so.

The failure to account for observational data is not due to the mechanics of the IPCC. It is a problem with the models. To further claim, as Gavin Schmidt of the NASA Goddard Institute for Space Studies (and 1/11th of realclimate.org) does, that the problem is that the models are simply 'insufficiently sensitive' is also flawed thinking. If the models do not account for observations, then it could be any number of assumptions which were flawed. It does not follow that things are worse than we thought, as Black's article implies - it merely shows that we were wrong.

Climate modelers and environmentalists want to argue that we can be certain about their predictions, yet when these predictions do not match observations, we are asked to believe that this reflects an even greater degree of certainty. For example, Schmidt says, 'uncertainty in model projections cuts both ways... My feeling (along with the authors) is that it is likely that the models are insufficiently sensitive.'

It takes a lot of guts to claim one moment that you have the science on your side, and the next that your feelings should be enough to convince the world that you're right. But gut instinct is no substitute for science.