Sunday, February 10, 2008

An Inconvenient Truth could be strengthened if it showed uncertainties in data

Our Energy Technology and Policy class motivated me to watch Al Gore’s film “An Inconvenient Truth” for the first time this week. Because of the widespread attention this film has received in our country’s popular culture, I assumed it would present a clear and startling message about global climate change, and, indeed, this was my impression from watching this film. While contemplating the approach that Mr. Gore used to convey this message, it occurs to me that this film would be substantially more effective if the uncertainties and errors bands would have been presented alongside at least some of the data presented.

I am trained as an engineer, with a significant component of my training being experimental research and deciphering trends from data. An integral part of noticing data trends is consideration of the uncertainty or “spread” of the data – if the trend in the data is significantly larger than the uncertainty in the data, the trend is a convincing one. Mr. Gore presents numerous plots of data and projections in this film, but none of them included any mention of data uncertainty (e.g. the obligatory “+/- x% margin of error” in the bottom corner, or error bars on the data points) or the spread of projections from to different sources (e.g. one group of scientists predicting a global temperature rise of y degrees while another group predicts z degrees). I have seen global climate change data from numerous sources outside this film; without even presently reviewing these, I feel confident that including the entire range of the data and projections reported by credible scientists would not dilute the principal message communicated in this film: that global climate change is real, dramatic, and it is currently happening. This additional information would not only leave the underlying message unchanged, it would strengthen this message against skeptical criticism from those who hope to discredit global climate change.

I suspect that Mr. Gore thought of this omission while writing and refining his presentations and this movie, and I suspect that he made a conscious decision to omit this extra data because it would either confuse or bore his audience. This film is not targeted to the scientific community, it is targeted to the masses, and based on its reaction it has been successful. I guess the masses are just not into error bars, and I guess Mr. Gore knows that.

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