This week’s chart of the week is data taken from the Essential Poll, which is reported by Crikey.
What it shows is a truly stark and remarkable advertisement for the power of self-interest. The older you are – and therefore the less likely you are to experience the dangerous consequences of climate change – the less likely you are to believe that human activity is leading to global warming.
While 70 per cent of those aged 18-24 believe humans are changing the climate (with just 15 per cent believing it's all natural), for those above 65 years, under 40 per cent believe human activity is changing the climate. The level of belief in climate change clearly and steadily declines with age.
Of course, what is perhaps most extraordinary is that no matter what the age group, the percentage that believe human-induced global warming isn’t occurring is noticeably out of kilter with what the climate science research literature suggests.
The most recent paper that attempted to estimate the degree of scientific agreement over whether human activity was causing global warming was published in 2013 by John Cook et al. It examined abstracts from 11,944 peer-reviewed climate-science journal articles published between 1991-2011. Of the papers which indicated a view on the topic, 97.1 per cent supported the proposition that humans were causing global warming.
This is on top of a 2004 paper by Naomi Oreskes, published in the journal Science, which came to very similar conclusions. It reviewed 928 abstracts, published in refereed scientific journals between 1993-2003, and listed in scientific journal database with the keywords 'climate change'. Of these, 75 per cent either explicitly or implicitly accepted the human induced global warming, 25 per cent took no position and none – that’s right, zero – rejected human-induced global warming.
It is also almost exactly in line with direct polling of scientists by Doran and Kendall-Zimmerman (2009); Rosenberg et al (2010); and Anderegg et al (2010) which found between 94-98 per cent scientists agreed human activity was leading to global warming.
Richard Tol pops up again
Which then rather strangely brings me back to the subject of yesterday’s article (The Lomborg man behind the IPCC mutiny), Richard Tol, and his odd campaign of criticism of the John Cook et al paper.
There can be no doubting Tol’s expertise as an economist, and his prominent role in trying to quantify in monetary terms the impacts of climate change (which in many cases requires profound moral judgements more akin to philosophy than economics).
He has been an author or lead author on IPCC reports related to the economic impacts of climate change and the costs of reducing emissions (covered in IPCC’s working groups 2 and 3)
However, he has had no role in the IPCC’s evaluation of whether or not the climate is changing, what are its causes and how might the climate change in the future as a result of increased levels of greenhouse gases. This is the subject of working group 1 and lies in the realm of the hard sciences involving physicists, chemists and geologists rather than economists such as Tol.
Given this, it seems rather odd that Tol has become so concerned about the paper by Cook and colleagues assessing the degree of agreement among academic researchers about global warming.
If you look through Tol’s blog and Twitter account you’ll find numerous mentions disparaging of Cook’s paper, the authors involved and the University of Queensland journal which published the paper. Tol seems to be suggesting that Cook and University of Queensland are engaged in some kind of cover-up to obscure the underlying data supporting the finding of 97 per cent agreement among the peer-reviewed literature for humans causing global warming.
Yet a great deal of the supporting data and methods for how Cook and his colleagues undertook their study is freely available. It is possible for anyone to replicate the study if they wish to see whether they come up with different results.
Yet Tol, rather than replicate the study, instead has been demanding from Cook, his manager and the vice chancellor of UQ data down to the tiniest detail, including the identity of people that rated the papers and even the timestamps of when papers were rated.
The bemusement his criticism has created is perhaps best summed up by a peer review rejection letter from Environmental Research Letters of his critique of the Cook paper.
On Tol’s claims of a cover-up, a reviewer responded:
One is left profoundly confused as to why Richard Tol is so focused on discrediting this paper. It doesn’t discuss matters related to the economics of climate change (his field of study), its findings are supported by very similar findings conducted by others using different methods and it is reasonably straightforward to replicate the study for crosscheck. In addition, as a further crosscheck, Cook’s study also got a sample of 1189 of the authors of the papers reviewed to provide their own ratings of their papers.
This gave 97.2 per cent agreement about global warming instead of the 97.1 per cent arrived at by independent raters.