In the conservative world of science, conclusions are couched in caveats and statements are chosen carefully to not seem overwrought. And in the world of climate science thatโs no different. For example, in their 2007 report, the Intergovernmental Panel on Climate Change (IPCC) issued a series of defined levels of certainty about their conclusions that looked likeย this:
โข โVirtually certainโ (considered more than 99% likely to beย correct)
โข โVery likelyโ (more thanย 90%)
โข โLikelyโ (more thanย 66%)
โข โMore likely than notโ (more thanย 50%)
โข โUnlikelyโ (less thanย 33%)
โข โVery unlikelyโ (less thanย 10%)
โข โExceptionally unlikelyโ (less thanย 5%)
So in the IPCCโs final report they made statements like, โGlobal climate change is โvery likelyโ to have a humanย cause.โ
According to a recent article in New Scientist this use of language may be one of the reasons the public is not sharing the same level of urgency to reduce greenhouse gas emissions that scientistsย have:
David Budescu of the psychology department at Fordham University in New York and colleagues asked 223 volunteers to read sentences from the IPCC reports that used these expressions. For example: โIt is very likely that hot extremes, heat waves and heavy precipitation events will continue to become moreย frequent.โ
They then asked participants to estimate on a scale of 0 to 1 the probability conveyed by eachย sentence.
Participants tended to underestimate the certainty of the sentences. Three quarters of respondents thought โvery likelyโ meant less than 90% certain, and nearly half thought โvery likelyโ meant less than 66% certain. Public understanding of climate change was slightly better if the readers were given a legend to referย to.
This month weโre giving away FREE copies Nobel Laureate Dr. Andrew Weaverโs new book Keeping Our Cool: Canada in a Warmingย World.
Go here to find out more details about DeSmogBlogโs monthly bookย give-away.
