Yesterday we reported that a study published in Science linking climate change and conflict sparked a bit of a debate. Turns out one of the authors of the study, Marshall Burke, wrote a lengthy blog post addressing criticisms from other academics. For example, Idean Salehyan of the department of political science at the University of North Texas, Denton says that the plant is experiencing increasing temperatures while conflict is declining.
Burke responds that Salehyan is not quite right. There are fewer civil wars since the mid-1990s, but civil conflicts have increased over the past few years. The analysis includes both large (more than 1,000 deaths) and small (more than 25 deaths) conflicts in its analysis. What is interesting is he goes on to say that the causal link is not clear using the New Kids on the Block (yes, them) as an example.
[T]here are about a bazillion other things that are also trending over this period. The popularity of the band New Kids On The Block as also fallen fairly substantially since the 1990s, but no-one is attributing changes in conflict to changes in NKOTB popularity (although maybe this isn’t implausible). The point is that identifying causal effects from these trends is just about impossible, since so many things are trending over time.
Our study instead focuses on papers that use detrended data – i.e. those that use variation in climate over time in a particular place. These papers, for instance, compare what happens to conflict in a hot year in a given country, to what happens in a cooler year in that country, after having account for any generic trends in both climate and conflict that might be in the data. Done this way, you are very unlikely to erroneously attribute the effects of changes in conflict to changes in climate.
Burke addresses other concerns in the post that adds further clarity, but are unlikely to convince critics of the study.