Suchergebnisse

This study exploits a sudden and abrupt decline in precipitation of the long rains season in the Horn of Africa to analyze the possible link between climate change and violent armed conflict. Following the 1998 El Niño there has been an overall reduction in precipitation levels – associated with sea-surface temperature changes in the Indian and Pacific Oceans – resulting in an increase in the number and severity of droughts. Given that the probable cause of this shift is anthropogenic forcing, it provides a unique opportunity to study the effect of climate change on society compared to statistical inference based on weather variation. Focusing on communal conflict in Ethiopia and Kenya between 1999 and 2014, exploiting cross-sectional variation across districts, the regression analysis links the precipitation decline to an additional 1.3 conflict events per district. The main estimates show that there is a negative correlation between precipitation and communal conflict with a probability of 0.90. Changing model specification to consider plausible alternative models and accommodate other identifying assumptions produces broadly similar results. The generaliziability of the link between precipitation decline and conflict breaks down when using out-of-sample cross-validation to test the external validity. A leave-one-out cross-validation exercise shows that accounting for climate contributes relatively little to improving the predictive performance of the model. This suggests that there are other more salient factors underlying communal violence in Ethiopia and Kenya. As such, in this case the link between climate and conflict should not be overstated.

AbstractWe clarify the distinction between direct and indirect effects of disasters such as Hurricane María and use data from the Puerto Rico Vital Statistics System to estimate monthly excess deaths in the immediate aftermath of the hurricane which struck the island in September of 2017. We use a Bayesian linear regression model fitted to monthly data for 2010–2016 to predict monthly death tallies for all months in 2017, finding large deviations of actual numbers above predicted ones in September and October of 2017 but much weaker evidence of excess mortality in November and December of 2017. These deviations translate into 910 excess deaths with a 95% uncertainty interval of 440 to 1390. We also find little evidence of big pre-hurricane mortality spikes in 2017, suggesting that such large spikes do not just happen randomly and, therefore, the post-hurricane mortality spike can reasonably be attributed to the hurricane.

Spagat and van Weezel have re-analysed the data of the University Collaborative Iraq Mortality Study (UCIMS) and found fatal weaknesses in the headline-grabbing estimate of 500,000 excess deaths presented, in 2013, by Hagopian et al. The authors of that 2013 paper now defend their estimate and this is our rejoinder to their reply which, it is contended here, avoids the central points, addresses only secondary issues and makes ad hominem attacks. We use our narrow space constraint to refute some of the reply's secondary points and indicate a few areas of agreement.

Hagopian et al. (2013) published a headline-grabbing estimate for the Iraq war of half a million excess deaths, i.e. deaths that would not have happened without the war. We reanalyse the data from the University Collaborative Iraq Mortality Study and refute their dramatic claim. The Hagopian et al. (2013) estimate has four main defects: i) most importantly, it conflates non-violent deaths with violent ones; ii) it fails to account for the stratified sampling design of the UCIMS; iii) it fully includes all reported deaths regardless of death certificate backing, even when respondents say they have a death certificate but cannot produce one when prompted; iv) it adds approximately 100,000 speculative deaths not supported by data. Thus, we reject the 500,000 estimate. Indeed, we find that the UCIMS data cannot even support a claim that the number of non-violent excess deaths in the Iraq war has been greater than zero. We recommend future research to follow our methodological lead in two main directions; supplement traditional excess death estimates with excess death estimates for non-violent deaths alone, and use differences-in-differences estimates to uncover the relationship between violence and non-violent death rates.