Food Prices and Riots

For a long while now I've been wanting a student to do some work on the link between food prices, riots and other kinds of conflict.  I've got a few basic ideas about how this could be done.  But I'm also busy and am sure a zillion others are busy working on this too.

So, one of my students, Jon Eyer, just sent me this link.  I don't know exactly what these folks are doing or where they got their data.  But the graph, reproduced below, sure is compelling.  We have had a few papers linking weather to conflict.  It seems to me the obvious mechanism in those papers was food prices. So why haven't more people looked at food prices themselves?

And since climate change may cause food prices to rise, Eric Hammel over at Thomas Ricks' FP blog is connecting the dots to argue that climate change is the biggest national security challenge we face.

That might be overstating the case.  But this does seem like a very real threat.

Update:  Marc Bellemare, who made a comment below, has a very nice new paper on this topic.  (Marc, is your paper posted somewhere?  Do you want to post a link?) 

While I haven't looked at this data or model carefully, it seems to me that the correlation--if real--is fairly convincing evidence of causality going from food prices to riots.  We all saw the events leading to price fluctuations shown in the graph.  It's pretty clear to me--and I think to anyone who followed this stuff--that events in Africa did not cause the price spikes.  We had bad weather in Australia, Russia, China and other places.  We had rapidly growing demand in Asia.  We had ethanol.  Then we had a series of rice export bans.  Then we had the fires and export bans in Russia.  Africa is way too small in terms of food demand and supply to markedly affect world food prices--which is what the graph seems to show--for causation to be going from conflict to prices.  Any other non-causal association would have to come from some third factor that happened to be correlated with both conflict and food prices.  It's hard for me to imagine what that third factor would be and what the mechanism would be.

Anyway. I'm sure there are plenty of interesting ways to look at this issue and to really get our heads around it I think we should take stock of all of them.


  1. Michael,

    I have seen that paper a few weeks ago when a reporter emailed me to talk about it. As far as I can tell, it's all correlations and no regression. I've seen more convincingly made claims for the supposed causal link between food prices and political unrest ;)

  2. I agree food prices are likely a very big factor in the riots. But with all due respect, I disagree strongly on the cause. I think you have to look far beyond weather to account for the rising food prices. First of all, NASA is now saying the climate change is being blown way out of proportion:

    I think you are way more likely to find a cause for the rising food prices in interest rates and inflation. Take a look at this chart
    and then look at yours again. Between roughly 20000 and 2004, while the Fed was dropping its rates to historically low levels, food prices went up from an index of around 90 to roughly 115. Then as the Fed starts gradually tightening between 2004 and 2006, food prices are basically moving sideways, a very minuscule gain. Then between 2006 and 2008, when the Fed drops its rate to essentially zero, the prices shoot up like there's no tomorrow, even though the economy was clearly already slowing down in 2007 and especially in 2008.

    If you're going to print all this money, you will have rising prices, I thought that was pretty obvious. Weather is just a camouflage.

  3. Matej: I'm sorry, but you are posting garbage news on my blog. One need only scratch surface of your source there to see it is garbage. In this blog we don't mislead people, at least not deliberately. So I hope you have posted that link out of ignorance as opposed to malice.

    I'm going to leave this up so people can follow the link and learn to differentiate garbage news from real news (eg., dig into the credential and background of the authors and the news source and compare that to what you might actually find at NASA: ). But put this kind of garbage up again and I'll delete it.

    The fact is that 98% of climate scientists agree climate warming is real and they've shown this measured in a zillion ways. If anything, realized warming has hit projections made in the 1950s fairly precisely. There is, of course, some uncertainty about overall magnitude of warming, which areas will warm more than others, and about the overall consequences of warming.

    As to what's causing higher food prices, weather isn't all of it. But it's some of it. And projections with warming are potentially quite disastrous. That doesn't mean it will be disastrous. It means this is a real threat that may be more imminent that some people realize.

  4. Michael,

    Here is a link to the latest version of my paper:

    I may also post something tomorrow or early next week about the Lagi et al. studies.

  5. Here's a paper on food prices and protests that reaches roughly the same conclusion using time series analysis:

    However, the headline is quite different. Funny how people interpret their results very differently.

  6. Michael,
    I really don't have a problem with people pointing out where my mistakes are and underpinning it with arguments. I wish you had done that. I'm not sure "garbage", "misleading" and "malice" count as arguments and I see no need for such language.

    I found this news in a couple of sources and thought it was rather interesting. But since you proposed, I followed your advice and made a short background check on the author, dr. Roy Spencer. He is a Principal Research Scientist at University of Alabama in Huntsville, Science Team Leader for AMSR-E on NASA's Aqua satellite and has served as senior scientist for climate studies at NASA’s Marshall Space Flight Center. He's received a few awards, including NASA Exceptional Scientific Achievement Medal and the American Meteorological Society Special Award. He's also published a few articles in the top ranking journals of his field. Having said that, I'm not arguing he is right. I obviously can't since I am not a meteorologist. I know a great many of his peers are very critical of his work and again it is hard for me to judge without the expertise. But I also know it wouldn't be the first time that the majority of scientists are wrong about something. Most economists today also claim printing money will get us out of depressions. It will not and they are wrong.

    But anyway, the whole debate on global warming was really just a side observation. I have my own thoughts about it but that is totally beside the point. My point is that easy money is the principal cause of rising prices and you didn't even address that. I argued that because central banks around the world, especially the Fed, are flooding the market with cheap money, prices of food are going up so drastically and I pointed to the interest rates which fit this explanation quite well, to which you replied "weather isn't all of it".

  7. Matej,

    I believe this explains Michael's assessment of Spencer's work:

    "The widely publicized paper by Roy Spencer and Danny Braswell, published in the journal Remote Sensing in July, has seen a number of follow-ups and repercussions. Unfortunately this is not the first time the science conducted by Roy Spencer and colleagues has been found lacking." The latest came Friday in a remarkable development, when the journal's editor-in-chief, Wolfgang Wagner, submitted his resignation and apologized for the paper."

    I'd have to say it's pretty rare that a scientific paper is so bad that an editor resigns.

    See also:


Post a Comment

Popular posts from this blog

Renewable energy not as costly as some think

Answering Matthew Kahn's questions about climate adaptation

Nonlinear Temperature Effects Indicate Severe Damages to U.S. Crop Yields Under Climate Change