What does Naomi Oreskes' study on consensus show?
What the science says...
In 2004, Naomi Oreskes performed a survey of all peer reviewed abstracts on the subject "global climate change" published between 1993 and 2003. She surveyed the ISI Web of Science database, looking only at peer reviewed, scientific articles. The survey failed to find a single paper that rejected the consensus position that global warming over the past 50 years is predominantly anthropogenic. 75% of the papers agreed with the consensus position while 25% made no comment either way (eg - focused on methods or paleoclimate analysis).
Benny Peiser's rebuttal
Benny Peiser repeated Oreskes survey and claimed to have found 34 peer reviewed studies rejecting the consensus. However, an inspection of each of the 34 studies reveals most of them don't reject the consensus at all. The remaining articles in Peiser's list are editorials or letters, not peer-reviewed studies. Peiser has since retracted his criticism of Oreskes survey:
"Only [a] few abstracts explicitly reject or doubt the AGW (anthropogenic global warming) consensus which is why I have publicly withdrawn this point of my critique. [snip] I do not think anyone is questioning that we are in a period of global warming. Neither do I doubt that the overwhelming majority of climatologists is agreed that the current warming period is mostly due to human impact."
The Viscount Monckton of Benchley's rebuttal
Despite Peiser's retraction, the same argument was repeated by the Viscount Monckton of Benchley (and plagiarised by Schulte). Here are the five studies Monckton claims Oreskes should've included in her survey as rejecting the consensus position:
- Multi-resolution time series analysis applied to solar irradiance and climate reconstructions (Ammann 2003) finds a correlation between solar activity and temperature. However, the temperature reconstructions used end in the mid-20th century before the modern global warming trend and don't address the consensus position that warming over the past 50 years is primarily anthropogenic. However, Amman has published a more recent study examining more up-to-date temperature records, concluding "although solar and volcanic effects appear to dominate most of the slow climate variations within the past thousand years, the impacts of greenhouse gases have dominated since the second half of the last century" (Ammann 2007).
- Solar Forcing of Global Climate Change Since The Mid-17th Century (Reid 1997) finds a link between solar variability and climate change, concluding that "solar forcing and anthropogenic greenhouse-gas forcing made roughly equal contributions to the rise in global temperature that took place between 1900 and 1955". Considering CO2 forcing before 1955 was much lower while solar forcing was much greater due to increasing solar activity, this conclusion only serves to reinforce the consensus position. More on the sun...
- Ad Hoc Committee on Global Climate Issues: Annual Report (Gerhard 2000) is non-peer reviewed. Oreske's survey only included peer reviewed studies. This is even conceded by Schulte.
- Atmospheric Greenhouse-Effect in the Context of Global Climate-Change (Kondratyev 1995) is a review, not an article - it doesn't actually include any research but reviews other studies. Oreskes' survey only included articles, not reviews.
- Review and impacts of climate change uncertainties (Fernau 1993) is another review, not an article, and is found in the Social Science Citation Index. Oreskes sampled articles only from the Science Citation Index.
Last updated on 21 July 2010 by John Cook.