NCPA - National Center for Policy Analysis


July 13, 2005

A recent survey of climatologists from more than 20 nations has revealed that scientists are evenly split on whether humans are responsible for changes in global climate; these findings refute a 2004 study that claimed that there is a scientific consensus that global warming is real and primarily caused by humans.

In December 2004, Naomi Oreskes published an article in the Washington Post that summarized her examination of 928 scientific papers on global warming. She claims that:

  • A review of scientific literature showed that scientists were in unanimous agreement that global warming is occurring and is being caused primarily by humans.
  • Since human activities are part of the reason the Earth's climate is heating up, we need to stop repeating nonsense about the uncertainty of global warming and start talking seriously about the right approach to address it, she adds.

Since then, two separate studies published in the London Telegraph dispute Oreskes' findings, claiming instead that climatologists are evenly split on the issue:

  • Benny Peiser conducted his own analysis on the same set of documents as Oreskes and concluded that only one-third backed the consensus view; only one percent did so explicitly.
  • Dennis Bray surveyed hundreds of climatologists and asked them the question: To what extent do you agree or disagree that climate change is mostly the result of anthropogenic causes?
  • He received 530 responses from 27 different countries and reported that more climatologists "strongly disagreed" than "strongly agreed" that climate change is mostly attributable to humans.

The results of these surveys suggest that the consensus is not all that strong and indicate that Oreskes? conclusion is not as obvious as once stated.

Source: James M. Taylor, "Survey Shows Climatologists Are Split on Global Warming," Heartland Institute, June 1, 2005; Naomi Oreskes, "Undeniable Global Warming," Washington Post, December 26, 2004; and Robert Matthews, "Leading scientific journals are censoring debate on global warming," London Telegraph, May 1, 2005.

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