Infrastructure built to protect cities from flooding can increase economic damages elsewhere.
Image credit: Michelle A. Hummel.
Edited by B. L. Turner, Arizona State University, Tempe, AZ, and approved November 27, 2013 (received for review August 26, 2013)
Significance
Whether climatic changes affect civil conflicts has been the subject of intense academic debate. Much of this controversy originates from a highly cited dispute between a previous PNAS paper—which finds that civil war incidence in sub-Saharan Africa is associated with increasing local temperature—and a subsequent rebuke of this result, also published in PNAS. We reexamine this apparent disagreement by comparing the statistical models from the two papers using formal tests. When we implement the correct statistical procedure, we find that the evidence presented in the second paper is actually consistent with that of the first. We conclude that the original grounds for the dispute over whether the climate–conflict relationship exists were erroneous.
Abstract
A recent study by Burke et al. [Burke M, Miguel E, Satyanath S, Dykema J, Lobell D (2009) Proc Natl Acad Sci USA 106(49):20670–20674] reports statistical evidence that the likelihood of civil wars in African countries was elevated in hotter years. A following study by Buhaug [Buhaug H (2010) Proc Natl Acad Sci USA 107(38):16477–16482] reports that a reexamination of the evidence overturns Burke et al.’s findings when alternative statistical models and alternative measures of conflict are used. We show that the conclusion by Buhaug is based on absent or incorrect statistical tests, both in model selection and in the comparison of results with Burke et al. When we implement the correct tests, we find there is no evidence presented in Buhaug that rejects the original results of Burke et al.
Footnotes
↵1S.M.H. and K.C.M. contributed equally to this work.
- ↵2To whom correspondence should be addressed. E-mail: kmeng{at}princeton.edu.
Author contributions: S.M.H. and K.C.M. designed research, performed research, analyzed data, and wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
See Commentary on page 2054.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1316006111/-/DCSupplemental.
Reconciling debate in climate–conflict studies
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- Sustainability Science
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