Ball or Aerosol?

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According to the likes of Bob Ward, George Monbiot, Ben Goldacre and Steve Connor, it is a well established fact that the slump in global temperatures over three decades in the middle of the last century is the result of changes in the composition of atmospheric aerosols following various clean air acts in the western world.

Failure to acknowledge this fact is ‘straightforward scientific dishonesty’, according to Monbiot, and ‘a major misrepresentation of the scientific evidence’, in the words of Ward. Goldacre described the question of the post-war temperature slump as a prime example of a denialist ‘zombie argument’ (it ‘survive[s] to be raised again, for eternity, no matter how many times [it is] shot down’) and wrote that it has ‘been answered already, ages ago’. It’s the aerosols, stupid.

We have stated repeatedly that such certainty is not justified by the state of scientific understanding of atmospheric aerosols (see links above). So it’s good to see Quirin Schiermeier’s piece in today’s issue of NatureThe real holes in climate science – which identifies aerosols as one of four problematic areas of climate change research (the other three being Regional climate prediction, Precipitation, and The tree-ring controversy):

Atmospheric aerosols — airborne liquid or solid particles — are a source of great uncertainty in climate science. Despite decades of intense research, scientists must still resort to using huge error bars when assessing how particles such as sulphates, black carbon, sea salt and dust affect temperature and rainfall.

Overall, it is thought that aerosols cool climate by blocking sunlight, but the estimates of this effect vary by an order of magnitude, with the top end exceeding the warming power of all the carbon dioxide added to the atmosphere by humans.

One of the biggest problems is lack of data…

Schiermeier goes on to describe how little is understood about the relative contributions of white aerosols (eg, sulphates, which have a cooling effect) and black carbon (which has a warming effect); how we don’t know the atmospheric aerosol composition in the present, let alone the past; how little we know about the way in which aerosols interact with clouds and other atmospheric processes, etc.

He doesn’t go into the implications of this lack of knowledge for our understanding of the post-war temperature slump. But it goes without saying that, if ‘Scientists have yet to untangle the interplay between pollution, clouds, precipitation and temperature’, then the claims of Ward, Monbiot, Goldacre, Connor et al are wildly off the mark, if not examples of ‘straightforward scientific dishonesty’.

Thankfully, neither is the post-war temperature slump mentioned in the obligatory list of long-debunked denialist arguments (Enduring climate myths) that accompanies Schiermeier’s article – something of a first for the genre.

The Nature piece is not without its faults. For a start, it is framed in terms of the putative attack on climate science by ‘deniers’. And Hans von Storch is already complaining that Schiermeier has misquoted him, and that the article ignores myths perpetuated by the orthodoxy (of which we could add a few of our own). But perhaps it has dealt the severe head trauma that was needed to finish off for good the real zombie argument – that ‘Temperatures declined after the Second World War as a result of sulphate pollution from heavy industry, causing global dimming. This is well-known to all climate scientists.

Let Them Eat Shrubbery

Science is often at its most newsworthy when it proves the blatantly obvious: getting drunk makes you more likely to fall over; sunbathing is a risk factor for sunburn, etc. But science that ‘proves’ something that journalists, commentators and policy bods like to think was blatantly obvious can also command more than its fair of column inches. Last year, for example, we reported on how a paper published by the Royal Society had proved once and for all that The Great Global Warming Swindle really did get it wrong about the influence of the sun on global warming, just like the Royal Society had said it had. More recently, there was the news that human activities had been attributed directly to the rise in temperatures at the Earth’s poles:

there was not sufficient evidence to say this for sure about the Arctic and Antarctic.

Now that gap in research has been plugged, according to scientists who carried out a detailed analysis of temperature variations at both poles.

Their study indicates that humans have indeed contributed to warming in both regions.

Which presumably came as a surprise to Naomi Oreskes, Professor of History and Science Studies at the University of California, San Diego, according to whom the matter had been settled decades ago. In fact, the ‘fact’ that polar temperatures have been increasing faster than in the rest of the world was the prime ‘fact’ presented by Oreskes in her influential lecture, The American Denial of Global Warming, to justify her thesis that the whole issue of global warming and what we should do about it was done and dusted in the 1970s.

The latest example is to be found in the Independent, where Steve Connor reports on how his own personal prejudices about the restorative effects of green space are now supported by ‘the science’:

Proof at last: living near parks and woodland boosts health, regardless of social class.

Another whose assumptions are now vindicated scientifically is David Tibbatts from the charity GreenSpace:

“The study confirms what we have been saying for many years – parks are important for health and everyone should have access to high quality, beautiful and vibrant green spaces.”

The ‘proof’ is provided by a study published in last week’s issue of the Lancet (free registration required). It presents evidence that the health gap between rich and poor is narrower in areas where there is easy access to green space. Having made a good stab at controlling for the effects of socio-economic class – no easy task – the authors of the paper find that socio-economic health inequalities are nearly halved in those areas where greenery is most easily accessible compared to where it’s most sparse.

Of course, whatever the Independent might tell us, a single study rarely ‘proves’ anything, especially in such a noisy, contingent science as epidemiology. As co-author of the study Richard Mitchell of the University of Glasgow told us on the telephone:

It’s the first time anybody has done this, and inevitably it raises more questions than it answers.

Like how big the effect is compared to socio-economic class itself, for example? The answer to that one is far from clear. It’s certainly smaller, as Mitchell confirmed, but it’s hard to tell how much smaller. That’s because Mitchell and his collaborator Frank Popham (University of St Andrews) have used a narrow measure of health – mortality rate before retirement age – that does not compare directly with data on life-expectancy, which is the usual measure of health inequalities. Comparing like with like would require a separate study using different datasets. Life expectancy is approaching a decade shorter for those in the lowest social class compared to to the highest in the UK. Mitchell and Popham estimate that close proximity to green space means that an additional 1328 people live beyond retirement age per year. But it takes some imagination to expect that the latter makes much impact on the former.

And does it really follow that town planners just need to make more space for trees? Which is the take-home message of Connor’s piece:

Dr Mitchell, who is based at the university’s department of public health and health policy, said: “We would encourage the Government to consider carefully what their policy on green spaces is and to bear this research in mind when planning urban areas for the future.”

In these deterministic times – when we see ourselves as slaves to economies, climates and our evolutionary psychologies – these are questions that nobody feels the need to actually ask. Complex political questions are just too easy to ignore when simple mechanistic answers are handed out on plates.

It’s also striking that, although the paper concerned was published as part of a special issue on social inequalities in health, none of the other papers have received nearly as much attention. This paper is media-friendly precisely because it confirms the prejudices of a media machine that consistently fails to challenge the prevailing orthodoxy of environmentalism.

Neither do the press reports mention any of the caveats that Mitchell and Popham raise in their paper:

We undertook a highly powered population study with a simple approach, using robust health outcomes from reliable data sources. The study was hypothesis driven, and that hypothesis was based on findings from a large amount of research. However, the study did have several weaknesses. First, the measure of exposure to green environments was restricted. Although we knew the proportion of green space in the area of residence of people who had died, we had to assume that individuals living in areas with equal proportions of green space actually had equal access to that green space. Had appropriate data been available, we could have used a measure of distance to defined green spaces as a proxy for access, although we would still have had no data for whether populations living closer to a specified green space did actually access it to a greater extent. Furthermore, quality of green space could be a substantial determinant of use and activity within it, and we had no data for quality. No national dataset describing the quality of green space to which the population has access in England is available.

Second, our data were cross-sectional. We had no means of knowing the extent to which individuals had access to green environments throughout their life. Migration before death (eg, to access residential care) could have placed some people into a distinctly different environment from that in which their disease was acquired or developed. If such migration varied by income group, our results could be affected. Since we have no data for migration patterns, we were unable to quantify the effect of this factor.

Third, and perhaps most importantly, the measure of green space might be associated with other risk factors that we have not controlled for in our models. One of the difficulties of exploring the effect of physical environments on health is that access to good physical environments is strongly associated with the socioeconomic position of individuals. Residual confounding is therefore a threat to studies of this type.

Mitchell and Popham suggest that a combination of increased opportunities and motivation for physical activity plus a reduction in stress-related health problems might account for their results. This is supported, they say, by the observation that inequalities in early death due to any cause and due to circulatory diseases were reduced by close proximity to greenery while class differences in deaths due to lung cancer and suicide were not. The kind of stress that leads to circulatory disease is, according to Mitchell ‘a different sort of stress’ to that which makes smoking attractive or leads to self-harm. That maybe. But that’s certainly a claim that requires scrutiny from the scientific community.

When we spoke to him, Mitchell made it clear that planting trees is no substitute for wealth redistribution:

No government in the UK is ever going to get elected on the kind of really radical redistribution you would need to close the gap that way. The extent to which the gap shrinks in the greenest areas is more than has been achieved by current policy in the UK for quite a long time though, so this is a sizable effect. It’s really important not to overlook the redistribution of wealth. But, while we’re waiting for the revolution, it’s good news that environment can exert what seems to be a substantial influence.

We share his frustration, if not his defeatism. Wealth inequalities might have increased under the New Labour government, but that’s surely something to revile rather than run with. Mitchell makes a similar point in the press release issued by the University of Glasgow:

“Obviously, resources must still be ploughed into trying to narrow the inequality gap between rich and poor, and with that will come advances in the population’s general health.”

But Mitchell himself isn’t always so circumspect. In an article he wrote for the Sunday Herald about this research, socio-economics doesn’t get a mention. But he does sign off with a call to action:

So, the next time there is a planning permission argument in which a local green space is at risk, bear in mind that the green space is worth protecting because it is making a contribution to your health, and those of the people around you.

It reminds us of our conversation back in July with marine biologist Jason Hall-Spencer, who told us:

When you’re interviewed, you can give your own personal point of view, but when you publish a paper that goes up for rigorous peer review, then it’s got to have the caveats and everything else.

Well, yes, you can. But it doesn’t follow that you should.

In support of his case that policymakers should heed the message of his study, Mitchell also told us that:

the other thing is, so far as we know so far, green spaces don’t do any harm.

Which could read like a mission statement for environmentalism. As we tend to argue quite frequently on this site, environmental policies introduced in the absence of any better ideas can and do do harm. Green spaces and policies compete by definition for space and resources with amenities and policies that might address class inequalities per se. And when basic services such as refuse collection and sanitation are being reinvented under the banner of environmentalism, tree planting is a convenient and attractive option for cash-strapped town planners.

We feel a bit mean picking on Mitchell. The bulk of the blame certainly does not fall on his shoulders. We don’t doubt that he’s doing good science, or that his intentions are noble. But he has a career to look after like the rest of us. And as a scientist, looking after one’s career means constantly justifying one’s research in policy terms. Then there is the tyranny of the news peg – the reporting of newsworthy single studies in the absence of context or caution – to consider. And the tyranny of ‘relevant’ science. And of ‘evidence’-based policymaking. And of ‘science communication’ policies that require scientists to seek to popularise their work as part of the job description. Combined, the result is that any tin-pot political philosophy can be ‘proven’ scientifically, which does an injustice to both politics and science.

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.

Fat People are Killing the Butterflies

Steve Connor, science editor at the Independent newspaper warns us that

Tropical insects rather than polar bears could be among the first species to become extinct as a result of global warming, a study has found. 

What does that even mean? Are the polar bears OK after all? Is the environmental movement looking for a new mascot for climate change? Is it out with the charismatic mega-fauna because of the environmental ethic that ‘small is beautiful’? But it’s nothing compared to the headline it appears under:

Insects ‘will be climate change’s first victims’ 

An image of a butterfly follows, with the caption…

Many tropical insect species, including butterflies, can only tolerate a narrow range of temperatures, and an average rise of 1C to 2C could be disastrous 

Contrast with the measured language of the Proceedings of the National Academy of Sciences article on which Connor reports, and which the journal has kindly made available for free:

Our analyses imply that, in the absence of ameliorating factors such as migration and adaptation, the greatest extinction risks from global warming may be in the tropics, where biological diversity is also greatest. 

This is not the first time the Independent has gone on about butterflies as the harbinger of doom. Back in March – a particularly cold March, as it happens – Environment Editor Michael McCarthy hit us with:

Last month, [climate change] produced its most remarkable image yet – a photograph, taken in Dorset, of a red admiral, an archetypal British summer butterfly, feeding on a snowdrop, an archetypal British winter flower. 

But as we pointed out, the red admiral is far tougher that McCarthy gives it credit for, occasionally making an appearance in Winter, and is certainly not unusual in Spring and Autumn. Yet again, the Independent is making claims about the vulnerability of species that aren’t consistent with the state of knowledge.

The BBC is no more level-headed about the research…

The scientists predicted such species would struggle to cope with the 5.4C rise in tropical temperatures expected by 2100. 

5.4C expected by whom? Well, expected by the anonymous author of the BBC article, apparently. Certainly, the IPCC makes no specific prediction for temperature rise this century. And 5.4ºC is not mentioned in the PNAS study, nor in the accompanying press release. The only match we can find is in IPCC AR4 where it is the top-end prediction for SRES scenario A2 (Table SPM.3), the range of which is 2.0-5.4ºC. But why pick 5.4ºC? If you’re just looking for a big number to scare people with, then why not plump for the upper value for the A1 scenario (1.4-6.4°C)? Is this like buying the second cheapest bottle of wine in a restaurant to prove you are not a skinflint? Or like Josef Fritzl wondering why everyone hates him when he could have been so much more horrible? [EDIT: The BBC has now “corrected” this error.]

Call us pedantic if you like; but imagine the outcry had the BBC reported that global temperatures are expected to rise by only 1.4ºC by the end of the century (the second lowest low point among the four AR4 SRES scenarios). But then, of course, it’s not just journalists (and activists) who are happy to over-egg the ecopocalyptic pudding. When, for example, Bob May (erstwhile President of the Royal Society and former chief scientific advisor to the UK government) confidently asserted in the popular media that a global temperature of 2ºC will put 15-40% of all species at risk of extinction, it was on the basis of a single, worst-case study. He was no less unobjective when he announced that climate swindler du jour Martin Durkin was also some sort of whacko HIV/AIDS denialist. And then there are the science academies, who, while being suspicious of the industry move towards open access publishing, are happy to make papers of the the-world-is-screwed-and-we’re-all-going-to-die variety available to all and sundry for free. Which is what the US’s National Academy of Sciences have done with this paper. And last year the Royal Society did it, too, when they published a paper which they claimed proved once and for all that the sun has absolutely nothing whatsoever to do with global warming. This wasn’t just any old paper; it was, in the words of the Royal Society itself, “the truth about global warming“. And for some strange reason, we are still expected to take these academies’ opinions on what we should do about climate change as the last word on truth and beauty – “respect the facts” as Bob May puts it.

Newspaper editors and headline writers could – possibly – be forgiven for not understanding quite how science works. It’s harder to see how science correspondents could. And it’s laughable that the science academies seem not to. Funnier is that scientists and science academies are only too happy to criticise journalists, newspapers and TV producers when they report the science ‘wrongly’ (and you can bet your house that none of them will be criticising the Independent or the BBC on this occasion). But what do they expect? What sort of example do they think are they setting?

As we keep saying, this is no conspiracy. It’s just that – as they’ve been trying to tell us for years – scientists are human, too. Being human and everything, scientists are as jittery about the future and unsure of their role in society as the rest of us. But just because it turns out that they are as anxious as the rest of the world, it doesn’t mean that there’s any reason to take the claims of environmentalists at face value, or any less reason to maintain objectivity. Just as global warming is convenient for local governments, directionless leaders and crisis politics, it is also convenient for scientists and science academies lacking raison d’être.

Science might never have been quite the objective producer of facts that we like to think it is. But that doesn’t mean it shouldn’t strive to be an objective seeker of facts. Because striving to be objective about the facts of the material universe is precisely what science is supposed to do. When it applies itself instead to arming political narratives with legitimacy and authority, it talks itself out of a job.