Predicting Future Climate: The Devil is in the Details

Scientists who simulate future climate work with programs that are coarse-grained. For example, they predict that the “globe” will, on average warm up over the next hundred years. They even predict that “high northern latitudes” will warm up to a greater extent than lower latitudes. “High latitudes” will also see more precipitation.

But what if you are a civil engineer and it’s your job to dig up your city’s streets and replace the storm drain pipes? Can scientists tell you how big the new pipes should be in order to handle the rain water that you are likely to see over the next 75 years? According to “Vital Details of Global Warming Are Eluding Forecasters” (Science, 14 October 2011, p. 173) the answer is no. Making detailed forecasts for a city as large as Seattle, a region as large as the Pacific Northwest, “or even the western half of the United States,” appears to be beyond the abilities of current simulation programs. Or is it?

Read the article to see just how controversial regional climate modeling can be.

 

Carbon Emissions: Making it Personal

In April 2010 (“Fooling Yourself with Statistics?“) we looked at an Oregonian article about a Metro study of greenhouse gases, “Most Oregon Greenhouse Gas Not What You Think.” We took Metro (and the Oregonian) to task for not drawing a clear line between the carbon emissions of entire sector (transportation) and the carbon emissions under the control of a single person.

The “Don’t Sweat the Small Stuff” graphic in the July/August 2011 issue of Sierra Club magazine makes the same point. The picture (see below) comes from Mike Berner-Lee’s book, How Bad Are Bananas? (Greystone, 2011). Even if some of these figures are off by a whopping factor of two, you can see that a few hours spent on vacation air travel can wipe out a thousand intelligent decisions about plastic bags, bananas, and paperback books. What was it my Dad used to say, ‘penny wise, pound foolish’?