Study Links Extreme Hot Weather with Conflicts in the Tropics

A new study has found a strong correlation between extreme hot and dry weather and conflict in the tropics. Host Marco Werman speaks with the study’s lead author, Solomon Hsiang, who looked back over more than 50 years of data on climate and conflict.

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Marco Werman: The conflict in Libya is at its heart about ending the decades old Gaddafi regime. The conflicts are often more complicated than they might appear. They’re influenced by a complex set of factors, including, perhaps, the weather. A study published today in the Journal Nature finds a significant correlation between the outbreak of conflict and the weather. More precisely, the study found a strong relationship between the outbreak in tropical countries, and regular climate variations caused by the global climate patter, known as the El Niño/La Niña-cycle. Solomon Hsiang was the lead author of the study, which he conducted as a doctoral candidate at Columbia University School of Public Affairs. He is now at Princeton University. Dr. Hsiang, you look back over more than 50 years of climate and conflict data for the study. In the simplest terms, what did you look at, and what did you find?

Solomon Hsiang: What we found that when the global climate was in the wetter, and cooler La Niña state, the risk of civil conflict in tropical countries was three in one hundred. So if you’d have a hundred countries, you would expect three to start a civil war in any given year. But then when the global climate shifts to its hotter and dryer El Niño state, we observed the risk of conflict actually doubles, all the way up to 6%, so six out of a hundred. This means, that since 1950 El Niño has played a role in approximately 20% of all conflicts around the world.

Werman: How often does that cycle happen, that El Niño /La Niña cycle?

Hsiang: The El Niño event occurs around every 4 to 7 years, but it’s a little bit random which makes it a little bit hard to predict.

Werman: Right, and given that randomness, is 20% of global conflicts influenced by these weather patterns a strong enough correlation, or is it coincidental?

Hsiang: It’s a very strong correlation in fact, in a statistical sense. We do other tests to make sure that this is not just a result that one would get by chance. One of the tests we do, is we look at those countries much further north that are not affected by El Niño. We look at whether or not they exhibit conflicts in El Niño years, and find that there’s actually no response. So you can think about it as something like a placebo test. We also look within the year. So, in the tropical countries where we observe conflicts, we look at what times they begin conflicts, in which months. We find that new conflicts that seem to be occurring in phase with El Niño, actually occur at the same time of year as the El Niño events occur.

Werman: What is it specifically about the El Niño /La Niña weather pattern that does this?

Hsiang: That’s a difficult question. We don’t have the data to answer that completely. We do know that El Niño leads to hotter and dryer conditions throughout the tropics. We also know that it leads to poor yields and low incomes in the agricultural sector throughout the tropics. So what it does, is it clearly causes economic contraction. How that leads to conflict, is still up for a debate.

Werman: I see. We should make it clear what this study does not look at, and that’s the relationship of man-made climate change to conflict. It’s a question that many people are asking these days: Will the warmer and more volatile climate that we’re already creating for ourselves lead to, or somehow worsen conflict around the world? What do you think about that?

Hsiang: That’s a very difficult question. One that we would love to answer if we could. The results of the study are somewhat limited to particularly we’re looking at El Niño. The structure of El Niño is quite different to the structure of human induced warming. El Niño happens very rapidly, and it happens mainly throughout the tropics, whereas human induced warming happens more gradually, and it’s going to affect the whole world. That said, the populations that are experiencing conflict in response to El Niño have been subject to El Niño cycles for thousands of years, and yet they still respond to these events with violence. So it’s a little bit difficult to imagine a situation where we’re able to adapt so successfully to future changes that happen only over a matter of decades, and are larger in absolute magnitude, that we’re going to be able to avoid violence altogether.

Werman: What do you think we can learn from this research, that’s going to be relevant for governments and NGO’s?

Hsiang: Well, one of our hope is that this can be of use to avert the humanitarian crisis associated with civil conflicts. Right now, our models of El Niño are sufficiently good that we can actually forecast it up to two years in advance. With this kind of advanced warning, we’re hoping that governments, international aid groups, international organizations, can sort of provide advanced warnings both to people on the ground and perhaps prepare themselves better for anticipated periods of protracted conflicts.

Werman: So knowing this for example, you might be able to say: there’s a civil strife in Somalia, we know that people are going to be on the move, and there could be a phantom, like there is a summer.

Hsiang: In fact, the events in Somalia were forecasted using El Niño forecasts two years ago, but it wasn’t really taken very seriously by the international community. So we’re hoping that our study will give more credibility to these kinds of forecasts, and help the international community take them much more seriously.

Werman: Dr. Hsiang, thank you very much for your time.

Hsiang: Thank you very much for having me.

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