Something has gone wrong with global warming. It’s not that the world has stopped heating up. It’s that the anti-warming political movement, which seemed almost unstoppable when the Intergovernmental Panel on Climate Change won the 2007 Nobel Peace Prize, has stalled.

Last week’s United Nations climate change conference in Durban ended with little more than an agreement to talk some more about what to do next. Even that was too much for Canada, which has just said no to emission-reduction targets. The activists blame recalcitrant governments and many commentators blame economic distractions. They are probably both right, but I think the activists’ own approach bears much of the responsibility.

While only experts can judge the strength of the scientific evidence for man-made climate change, no technical knowledge is required to be troubled by the way the activists present their case. The willingness to describe knowledgeable opponents as “deniers,” a word previously used only for fantasists about Nazi atrocities, suggests a very unscientific attitude.

The “Climategate” emails show scientists so passionate about their beliefs that they are unwilling to brook opposition. Fervor seems to have led to overconfidence. The status of the claim that recent years have been by far the warmest in a millennium has been downgraded from certain in 2001 to likely or mistaken (depending on the expert consulted).

The activists’ excess of passion and certainly has led them to a dogmatic conviction that a radical policy — rapid and sharp reductions in carbon dioxide emissions — is required to save the world. Since industrial economies cannot yet function without using large amounts of energy generated by burning carbon, the anti-carbon prescription equates to a campaign against prosperity — tough on rich countries (too tough for Canada to bear) and practically a sentence of economic stagnation for poor ones.