Continuing with the fifteenth lecture from Professor Michael Spagat’s Economics of Warfare course that he gives at Royal Holloway University. It is posted on his blog Wars, Numbers and Human Losses at: https://mikespagat.wordpress.com/
This lecture addresses the impact of global warming on armed conflict over time. My previous post on the subject concerned a cross-country analysis of the impact of temperature on civil wars in sub-Saharan Africa that was not very convincing, even though it made the rather shocking claim that: “Burke et al. go on to predict 393,000 excess battle deaths caused by climate change…” (my bolding).
Probably the most interesting aspect of the presentation was when Dr. Spagat’s TA used the model to make predictions from the period 2003-2013 and also tested the model with the temperature variable removed from the model. Dr. Spagat’s conclusion was (slide 22) “…They mean that temperature is not very useful for predicting civil war….”
Then starting slide 23, the presentation looks at an effort by O’Loughlin et al. to look the impact of temperature and precipitation not by cross-country analysis, but by looking at local variations. They divided up East Africa into grid that are about 100 by 100 kilometers. They then measured it to a dependent variable that was the number of violent incidents. They then tested it using a “negative binomial regression model” (another methodology I have no experience using). They ran five different simple models, of which only one produced a statistically significant measure, and it was negative (meaning more rain = less violence). A sixth model he ran (“GAM splines”) did provide some fits by using different sized deviations and fitting a smoothed curve to these estimates (I really haven’t take the time to figure out what he did). The end result was that this last model provided some indication that:
- Wet weather reduce violent incidents
- Large warn deviations (unusually warm weather) increase violent incidents.
The O’Loughlin paper is here: http://www.pnas.org/content/109/45/18344.full
All the papers discussed are in the Dr. Spagat’s slides, so you can see the original. Just to grab a few quotes from the O’Loughlin paper:
- “Recent studies concerning the possible relationship between climate trends and the risks of violent conflict have yielded contradictory results….”
- “Sweeping generalizations have undermined a genuine understanding of any climate–conflict link, whereas cumulative results from the numerous studies of individual communities are difficult to summarize.”
This, of course, harkens back to my first observations over a decade ago when I saw the CNA study that was predicting increased wars, violence and problems (and perhaps increased U.S. intervention) as a result of climate change. Again….we really do not know if this is the case. Added to that, some of the areas that may be most affected by climate change are the areas that the United States are not likely to get heavily involved in (read: Sub-Sahara Africa). So, while climate change may be a very real problem, it may not have a huge impact on our defense policy and planning in the next couple of decades outside of the Arctic (and the Arctic is a whole separate discussion). We should be careful not to assume a significant cause-and-effect (climate change = many more wars) when there is not strong evidence to do so.
The link to the lecture is here: http://personal.rhul.ac.uk/uhte/014/Economics%20of%20Warfare/Lecture%2015.pdf
