Changing Minds About Climate Change: Belief Revision, Coherence, and Emotion

Scientists sometimes change their minds. A 2008 survey on the Edge Web site presented more than 100 self-reports of thinkers changing their minds about scientific and methodological issues (http://www.edge.org/q2008/q08_index.html). For example, Stephen Schneider, a Stanford biologist and climatologist, reported how new evidence in the 1970s led him to abandon his previously published belief that human atmospheric emissions would likely have a cooling rather than a warming effect. Instead, he came to believe – what is now widely accepted – that greenhouse gases such as carbon dioxide are contributing to the dramatic trend of global warming. Similarly, Laurence Smith, a UCLA geographer, reported how in 2007 he came to believe that major changes resulting from global warming will come much sooner than he had previously thought. Observations such as the major sea-ice collapse in Canada’s Northwest Passage had not been predicted to occur so soon by available computational models, but indicated that climate change is happening much faster than expected. Evidence accumulated over the past three decades is widely taken to show that global warming will have major impacts on human life, and that policy changes such as reducing the production of greenhouse gases are urgently needed. However, such scientific and policy conclusions have received considerable resistance, for example from former American president George W. Bush and Canadian Prime Minister Stephen Harper. A philosophical theory of belief revision should apply to the issue of global warming by explaining how most scientists have come to accept the following conclusions: