Specifically the study mentions Sudan, first in 1963, then 1976, and finally in 1983. The fighting which started in 1983 continued for 20 years and resulted in 2 million deaths.
El Salvador, the Philippines, and Uganda were plunged into turmoil during a 1972 El Niño.
Angola, Haiti, and Myanmar experienced serious civil conflict starting in the 1991 El Niño year.
Congo, Eritrea, Indonesia, and Rwanda suffered deadly conflict during the 1997 El Niño.
Wealthier nations are better at keeping calm through disruptive El Niño events. Australia is influenced by ENSO, but has never had a civil war.
"But if you have social inequality, people are poor, and there are underlying tensions, it seems possible that climate can deliver the knockout punch," said Hsiang.
"No one should take this to say that climate is our fate. Rather, this is compelling evidence that it has a measurable influence on how much people fight overall," said coauthor Mark Cane, a climate scientist at Columbia's Lamont-Doherty Earth Observatory . "It is not the only factor–you have to consider politics, economics, all kinds of other things."