The El Niño Southern Oscillation and Geopolitical Risk

TECHNICAL SUMMARY

This paper investigates whether the El Niño Southern Oscillation (ENSO)—the warming and cooling cycle in the central and eastern Pacific Ocean that affects both global atmospheric and ocean conditions—is a driver of geopolitical risk at the global scale. Using nonlinear cross-convergent mapping, a technique for characterizing causal relationships in dynamic systems, it finds ENSO is causally related to geopolitical risk at the global level, but that finding is not replicated at the country level for countries whose economies are most strongly influenced by ENSO cycles. Put differently, ENSO-related geopolitical risk is an emergent phenomenon evident only at the Earth system level. Then, using monthly observations of ENSO and geopolitical risk, the paper reports a curvilinear, contemporaneous relationship between ENSO and risk, with La Niña conditions associated with lessened geopolitical risk relative to El Niño and neutral climate conditions. The effects are statistically and substantively significant, and the relationship is demonstrated to be stronger in more recent decades (post-1990). The effect for geopolitical risk of transitioning from La Niña to neutral ENSO conditions is of similar magnitude to that of the outbreak of a major interstate war. 

PLAIN LANGUAGE SUMMARY

Prominent figures have explicitly linked high-profile armed conflicts and associated humanitarian disasters in some parts of the world to climate change. This working paper assesses the effect of the El Niño Southern Oscillation (ENSO)—the warming and cooling cycle in the central and eastern Pacific Ocean that affects both global atmospheric and ocean conditions—on global geopolitical risk, or risk of diplomatic or militarized disputes between and within countries. Existing research links El Niño—the warm portion of the cycle—to natural disasters, failed harvests, rising food prices, slower economic growth, and other factors leading to political instability and armed conflict within countries. However, the effects for interstate conflict—historically, the primary driver of geopolitical risk—are less clear. Using a methodology to analyze cause-and-effect relationships, this paper establishes a causal link between ENSO phases and fluctuations in geopolitical risk on a global level but, perhaps surprisingly, not at individual country levels, even those whose economies are most affected by ENSO-related natural disasters. The analysis indicates that cool/La Niña conditions are associated with decreased geopolitical risk compared to warm/El Niño and normal conditions in the central Pacific, and that the effect of ENSO on geopolitical risk has been stronger in more recent decades. The effect on geopolitical conditions is of similar magnitude to the outbreak of a major interstate war.