YouTube video available here. Firefox users can apparently see it fine, but Explorer is having problems.
A statement is not true just because thousands of scientists say it is. Nevertheless, media coverage of climate change has frequently implied that:
- thousands of scientists collectively produce the Intergovernental Panel on Climate Change's report and
- those scientists all agree that humans are responsible for the warming trend recorded in the late 20th century
A good example of this sort of media coverage can be found at 5:35 to 5:45 minutes of the above video.
It has therefore been a difficult task to communicate certain facts to the general public. First, among the thousands of souls involved in the IPCC process, many are not hardcore scientists at all. They are economists, bureaucrats, industry representatives, and professional activists. (See this 8-page PDF of expert reviewers who provided feedback on the section of the report produced by Working Group 3. Notice it is their affiliation the IPCC tells us about - not their scientific credentials.)
Additionally, a large number of those who worked on the IPCC report are academics from other disciplines. Some of these people have built careers by speculating on the effect global warming could have on a variety of matters at some time in the distant future.
(See, for example, Dr. Daniel Scott, a contributing author to chapter 14 of the IPCC's Working Group 2 report and a Canadian geography professor. In recent years he has travelled to Tunisia, Germany, Greece, France, England, Puerto Rico, Switzerland, Australia, New Zealand, Sweden, Scotland, Italy, South Africa, Las Vegas, and numerous other destinations to deliver papers on the effect climate change might have on golf, ice-fishing, alpine skiing, cottagers, national parks, and tourism events in Canada's capital city. Nice work if you can get it.)
In other words, it's anybody's guess how many of the people involved in producing the IPCC report - as authors or expert reviewers - are actually equipped to evaluate firsthand the relevant science supporting the hypothesis that humans are to blame for climate change.
I don't mean to disparage anyone here, only to point out that it's an open question whether a given economist or geography prof has truly worked through the science for himself. In many cases, he's surely just accepted the judgment of others.
In any event, the large group of people who contributed to the IPCC report were never asked whether they believe humans are responsible for climate change. Nor were they asked what portion of the overall change should be assigned to human activity and what portion should be assigned to natural causes. It just didn't happen.
Rather, the conclusion that humans cause climate change was decided in one chaper out of a total of 44 in the IPCC report. Only the folks who worked on chapter nine of the Working Group 1 report got a voice.
According to John McLean, who has crunched the numbers:
Chapter 9...had 53 authors in total but more than 40 were part of a network of people who worked previously together. In direct contradiction to the IPCC's statements that the team of authors should have a wide range of views and experiences, most were climate modellers and there were many instances where several authors were associated with the same establishment...
The second draft of chapter 9...received comments from 55 people and 7 governments. Of these 62 only 5 reviewers explicitly endorsed the overall chapter...
Fifty-three authors and five reviewers are all that can be said to explicitly support the claim of a significant human influence on climate. [bold added] (p. 2)
Persistent souls like McLean have been trying, for years, to get someone to pay attention to this very serious misunderstanding. But they may as well have been banging their heads against a brick wall.
Which is why it's so important, as Bishop Hill points out today, that Mike Hulme (a high profile climate change researcher at the University of East Anglia) is now acknowledging that McLean has a point.
In a forthcoming paper (22-page PDF) Hulme writes:
Claims such as ‘2,500 of the world’s leading scientists have reached a consensus that human activities are having a significant influence on the climate’ are disingenuous. That particular consensus judgement...is reached by only a few dozen experts in the specific field of detection and attribution studies; other IPCC authors are experts in other fields. [bold added] (pp. 10-11)
Got that? We the public have been misinformed, repeatedly, about the number of IPCC scientists who've explicitly endorsed the human-climate-change link.
If the planet really is in peril, we need clarity about facts such as these - not spin.
h/t to reader RG