The El Nino Southern Oscillation (ENSO) is generally thought to be the main reason for inter-annual warming or cooling.

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"Certainly ENSO affects weather and precipitation and humidity around the world, " said Jeffrey Shaman from Columbia University in New York.

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La Nina is the cold cousin of El Nino - the two collectively making up the El Nino Southern Oscillation (ENSO).

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"This doesn't provide any explanation of a mechanism for the connection between the ENSO cycles and conflicts, and I'm quite puzzled about what it could be, " he told me.

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Much of the variability in global TC ACE is explained by the concomitant changes or evolution in the character of the El Nino Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO).

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The examplar is Australia, one of the countries whose climate has been most badly affected by ENSO variations in recent decades, but which did not register a single civil conflict in the half-century research period.

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As they note, changes driven by ENSO are fairly rapid, from one year to the next - very different from the underlying upwards march of temperatures (and concomitant changes in other things) driven by greenhouse gas concentrations.

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Removing ENSO does not affect this.

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