In a report on a climate change seminar, Bernd Ströher and Benny Peiser write:
Particularly revealing were the almost sensational results of a survey conducted by Prof. Bray among some 500 German and European climate researchers. The results show impressively that the much-repeated claim of a “scientific consensus” on anthropogenic global warming is a carefully constructed piece of fiction: According to the survey results, some 25% of European climate researchers who took part in the survey still doubt whether most of the moderate warming during the last 150 years can be attributed to human activities and CO2 emissions.
Robert Matthews writing in the Telegraph claims the scientists were even more skeptical: (my emphasis)
Prof Dennis Bray, of the GKSS National Research Centre in Geesthacht, Germany, submitted results from an international study showing that fewer than one in 10 climate scientists believed that climate change is principally caused by human activity.
As with Dr Peiser’s study, Science refused to publish his rebuttal. Prof Bray told The Telegraph: “They said it didn’t fit with what they were intending to publish.”
40. Climate change is mostly the result of anthropogenic causes.
strongly agree 1 2 3 4 5 6 7 strongly disagree 9% 25% 21% 14% 8% 11% 10%
The Telegraph is only counting the 9% who chose 1 on the seven-point scale as agreeing with the statement. This is not correct. Clearly, responses 1,2 and 3 all indicate agreement with the statement. Still, a significant fraction disagree with the statement.
Is global warming skepticism amongst climate scientists as widespread as this survey indicates? To answer this we need to look at how the sampling was conducted:
The 2003 survey was conducted as an on-line survey. The existence of the survey was posted in the Bulletin of the American Meteorological Society, the Climlist server, and was sent to institutional lists in Germany Denmark and the U.K. As an effort to prevent general access to the survey, the survey was password protected. The password was contained in the informative message distributed according to the above.
However, the information about the survey was reposted (mail list membership required to read link) to the climatesceptics mail list by Timo Hämeranta on Sep 20 2003: (my emphasis)
the survey (below) is directed to those involved in the natural sciences related to climate change and not, for example, those involved in policy analysis or economic issues.
I suggest that you participate by completing the questionnaire (instructions to participate below).
Lähettäjä: CLIMLIST Climatology Distribution List
[mailto:CLIMLIST@...] Puolesta CLIMLIST
Lähetetty: 19. syyskuuta 2003 18:12
Aihe: Survey of Climate Scientists
CLIMLIST Mailing Number 03-09-24
Origin: “Dr. Dennis Bray”
Due to the nature of the distribution of electronic surveys some recipients of this message might have received the same previously. If that is the case, my apologies. Please do not submit the survey twice, although, once would be much appreciated. The survey is directed to those involved in the natural sciences related to climate change and not, for example, those involved in policy analysis or economic issues. Your discretion in choosing to participate in the survey on this basis would be greatly appreciated, as would your cooperation in making the survey a success. If you know of colleagues not contained on climlist but involved in the climate sciences, it would be appreciated if you could bring this survey to their attention with the suggestion that they too might like to participate by completing the questionnaire. Simply forwarding this message is likely the most convenient method.
… If you do choose to participate, the survey can be reached by opening your web browser and going to the following link:
When the page opens click the link to “survey of climate scientists” Here you will be asked for a username and password.
For username enter “respondent” (without quotation marks)
For password enter “ccsurvey” (again without the quotation marks).
The survey is password protected as an effort to limit the respondents to those involved in the climate sciences. There is also the option to print the survey from a PDF file and submit though regular postal services. Electronic submissions do not transmit your email address and consequently anonymity is ensured. Thank you in advance for your cooperation.
Since the survey was anonymous, there is no way to ensure that only climate scientists participated and no way to prevent people from submitting the survey multiple times. Furthermore, the survey was distributed on the climatesceptics list which has over 200 members, almost all of them strongly skeptical about global warming. Since the total number of participants was just 557, this could serious skew the results. I don’t believe that the results of this survey are representative of the views of climate scientists.
Update: Bray has some on the methodology here. The only thing Bray did to check for multiple responses by the same person was to see if there were any responses that were exact duplicates.
Update 2: Bray replies.