The Flaw of Averages in Climate Change

The Average Temperature May Not be on the Rise

by Sam L. Savage


The average future temperature may not be going up after all. There are big uncertainties in future carbon dioxide and methane levels, as well as the rate at which glaciers will melt, and a host of other things that will certainly drive up the temperature of the earth. But don’t despair. There is also a lot of uncertainty surrounding the occurrence of global nuclear wars, killer asteroid strikes, or eruptions of super volcanoes. And one of these alone could turn the planet into an uninhabitable ball of ice.

For argument’s sake, suppose that if we take these cooling disasters into account, the average future temperature is the same as today. Using Flaw-of-Averages logic, one would argue that we will therefore be as comfortable in the future as we are today. This ridiculous example is meant to convince you that we should not be approaching uncertain environmental issues based on average assumptions, but should use a probabilistic approach. In fact, due to the nonlinearity of environmental effects, the Flaw of Averages impacts nearly every level of analysis.

SIPmath Flood 3.gif

For example, consider an uncertain flood crest that averages 2.4 meters, as shown in the figure below. Because the dikes are 2.5 meters high, the impact of the average flood is zero, but in this example, the average impact is $5.49 million. I urge you to download the interactive model here.

To learn more, see my article in Public Sector Digest on Curing the Flaw of Averages in Climate Change.

Also, on October 3rd, I will be joining Valerie Jenkinson and Jerry R. Schubel in a live webinar on Building Asset Management Strategies in the Age of Climate Change for Coastal Communities.

© 2019 Sam Savage