The recent cold snap in the United States was, apparently, seen by many as undermining the claims of a majority of climate scientists that human activity was gradually – but potentially catastrophically – warming the climate.
But, according to this article from the Associated Press, the most remarkable things about the cold was that it was not all that cold (merely the 55th coldest day since 1900) and that cold days appear, now, to be relatively rare (though, of course, a random element of statistical fluctuation may also have contributed to the length of the period – 17 years – since the last very cold period.)
One other thought – the cold in the US seems to have been matched by a very mild (in temperature, if not much else) winter in Western Eurasia. I still have nasturtiums – usually killed off by frosts long before now – growing in the garden. I would not go so far as to say they were thriving (the last flowers were seen in December) but they are still going…
The last six weeks has seen the UK hit by a number of storms and surely climate change is to blame? Well, no, you cannot say that.
Not because climate change is not to blame. But because we just cannot definitively pin down a weather event to a change in climate. (Of course, this does not bother many on the other side of the argument, but those who defend science should judge themselves by higher standards.)
But we can, if the resources are available, calculate the statistical probability that specific weather events are linked to climate effects.
This is the abstract of a 2011 paper published in Nature:
Anthropogenic greenhouse gas contribution to flood risk in England and Wales in autumn 2000
Interest in attributing the risk of damaging weather-related events to anthropogenic climate change is increasing1. Yet climate models used to study the attribution problem typically do not resolve the weather systems associated with damaging events2 such as the UK floods of October and November 2000. Occurring during the wettest autumn in England and Wales since records began in 17663, 4, these floods damaged nearly 10,000 properties across that region, disrupted services severely, and caused insured losses estimated at £1.3 billion (refs 5, 6). Although the flooding was deemed a ‘wake-up call’ to the impacts of climate change at the time7, such claims are typically supported only by general thermodynamic arguments that suggest increased extreme precipitation under global warming, but fail8, 9 to account fully for the complex hydrometeorology4, 10 associated with flooding. Here we present a multi-step, physically based ‘probabilistic event attribution’ framework showing that it is very likely that global anthropogenic greenhouse gas emissions substantially increased the risk of flood occurrence in England and Wales in autumn 2000. Using publicly volunteered distributed computing11, 12, we generate several thousand seasonal-forecast-resolution climate model simulations of autumn 2000 weather, both under realistic conditions, and under conditions as they might have been had these greenhouse gas emissions and the resulting large-scale warming never occurred. Results are fed into a precipitation-runoff model that is used to simulate severe daily river runoff events in England and Wales (proxy indicators of flood events). The precise magnitude of the anthropogenic contribution remains uncertain, but in nine out of ten cases our model results indicate that twentieth-century anthropogenic greenhouse gas emissions increased the risk of floods occurring in England and Wales in autumn 2000 by more than 20%, and in two out of three cases by more than 90%.
At the time of those floods I was a special adviser to Paul Murphy, the Secretary of State for Wales, and accompanied him when he visited stricken areas of North Wales. It would be an exaggeration to say we saw Biblical levels of distress and destruction, but they were unlike anything I had seen at first hand.
As the abstract makes clear the paper certainly does not say “floods were caused by climate change” – indeed it goes so far as to say that “observed UK fluvial-flood and high-flow trends for recent decades suggest no clear evidence for any change above that of natural variability17, 18, mirroring the mixed picture in observed precipitation changes19, 20.”
And, moreover, the authors state that the risk of some flooding events may actually be reduced by the factors they say increased the flooding risk from heavy rainfall: climate change is complex, something else those who oppose the science that underlies it are often unwilling to concede as they focus on populist arguments about this week’s weather or short-term trends.
An original version of this article sought to make the fairest updated comparison with the 0.2C warming rate stated by the IPCC in 2007.
It drew on the following sentence in the draft 2013 summary: ‘The rate of warming over the past 15 years… of 0.05C per decade is smaller than the trend since 1951, 0.12C per decade.’ This would represent a reduction in the rate of warming by a little under one half.
But critics argued that the 0.2C warming rate in the 2007 report relates only to the previous 15 years whereas the 0.12C figure in the forthcoming report relates to the half-century since 1951. They pointed out that the equivalent figure in the 2007 report was 0.13C.
This amended article compares the 0.05C per decade observed in the past 15 years with the 0.2C per decade observed in the period 1990-2005 and with the prediction that this rate per decade would continue for a further 20 years.
A sentence saying that the IPCC now projects warming by 2035 to be between 0.4 and 1.0C, which was reproduced accurately from the leaked document, has been deleted, following representations that these figures were an IPCC typographic error.
I think it is a good thing that they are willing to admit they got it wrong – even if they are now seeking to change the goalposts in their attempt to justify their claim that scientists got it all wrong.
The figure above is from one of the most important and most influential scientific papers ever published: Regression Towards Mediocrity in Hereditary Stature in volume 15 of “The Journal of the Anthropological Institute of Great Britain and Ireland” (in fact JSTOR claims it is copyright to them from 1886, but I am betting that the copyright has lapsed).
In this paper the eminent Victorian scientist Francis Galton showed that, actually, the children of taller people tended to be smaller than their parents and vice versa – an example of the phenomenon we would now call “regression towards the mean“.
Such regressions do not replace longer-term trends (you can see from the figure above that Galton estimated the average height of adult males to be just over 5 foot 8 inches – about my height – and today the figure is closer to 5 foot 10 inches), instead they are a reflection of the random noise in the system.
But although this has been understood by scientists since 1886, it seems it has yet to penetrate the Mail on Sunday – who claimed that because the retreat of arctic sea ice in 2013 did not match 2012’s all-time record the science of climate change was dead in the water.
In fact the trend, regression towards the mean notwithstanding, is pretty clear – as this ought to make clear to anyone able to read any sort of plot…
Sadly, I increasingly fear, in future decades our children and their children are likely to look back on this second decade of the twenty-first century as a wasted opportunity to put the findings of science into action.
The scientific consensus on climate change is clear and stable. The only “argument” is about just how rapidly the threat is growing. Yet that argument – in fact often just a refinement of figures based on better measurements and more refined models – is being used to claim that the science is not agreed and that, somehow, it is legitimate to claim that climate change denial is good science.
First of all – leaked findings of draft reports are not generally to be regarded as scientific reports – science does not work that way. Papers are reviewed and finalised for good reasons.
Secondly, misreporting renders even your attempts to manipulate such leaked draft reports as little better than chip paper.
And that is just what the Mail on Sunday – one of the leading engines of the science-denial brigade in the UK – have been caught doing.
As this excellent blog shows – the Mail on Sunday claimed that scientists were about to reduce their estimate of the long-term warming by 50% when, in fact, the reduction was about 8% (or one one-hundredth of a kelvin).
Such journalism – personally I think this sort of reportage belongs in a comic, not a serious national newspaper – poisons public debate all too often. And, without wanting to comment on the individual views of the journalist concerned here – one David Rose – it is plain there is a determined attempt by some to have ideology trump science. That cannot be allowed to stand.
The Heartland Institute, reports the Guardian, are claiming that the internal memo which appears to show that they are working on plans to “dissuade teachers from teaching science” is a “total fake”.
Heartland had earlier admitted that other documents published alongside the memo were genuine, but later backtracked on that.
They then went on to refuse to discuss the matter – including, it would appear, the issue of whether the controversial memo was a fake – any further.
Much of the material in the memo is similar to that in the other documents that Heartland had earlier admitted to be genuine. But only the memo contains the statement that the ultimate aim of Heartland is to cripple science teaching through fear.
The original publishers of the leaked documents, the DeSmog blog, are standing by their story.
The usual claim from the climate change deniers is that they are merely pointing out that climate science is controversial or disputed. But their internal documents reveal what this is really all about (emphasis added):
Principals and teachers are heavily biased toward the alarmist perspective. To counter this we are considering launching an effort to develop alternative materials for K-12 classrooms. We are pursuing a proposal from Dr. David Wojick to produce a global warming curriculum for K-12 schools. Dr. Wojick is a consultant with the Office of Scientific and Technical Information at the U.S. Department of Energy in the area of information and communication science. His effort will focus on providing curriculum that shows that the topic of climate change is controversial and uncertain – two key points that are effective at dissuading teachers from teaching science.
All of this is funded by a mystery figure known as the “Anonymous Donor”. It is tempting to make a song and dance about Microsoft’s role in funding the shamans too – but it seems their money goes on a project called “ITTN” – which mainly seems to be about stopping US regulators injecting some competition into the telecoms and ICT market over there.