Tree rings tale of Atlanta’s mistake

Neal Neil Pederson and colleagues have a new paper (pdf) using tree rings to reconstruct flows in the Apalachicola–Chattahoochee–Flint that offer another stark reminder of a classic water management dilemma: make water management decisions during a wet time and you’ll be screwed by the regression to the mean.

We’ve seen this story before, with the Colorado River’s allocation, made during the unusually wet 1920s. The new tree ring work on the ACF basin shows a remarkably similar story, according to Pederson et al:

Our results indicate that the era in which local and state water supply decisions were developed and the period of instrumental data upon which it is based are amongst the wettest since at least 1665. Given continued growth and subsequent industrial, agricultural and metropolitan demand throughout the southeast, insights from paleohydroclimate records suggest that the threat of water-related con?ict in the region has potential to grow more intense in the decades to come.

As always, my book has lots more on tree rings.

(updated to correct spelling of Pederson’s name)


  1. There are two problems with regression to the mean. The first is that it assumes no trend in its strongest form, so better said regression to the trend for policy purposes.

    The second is kind of neat, if you assume a random walk, the easiest place to reach a new extreme is from an extreme.

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