Different kinds of El Niño warming events in the tropical Pacific Ocean can have widely varying effects on global temperatures.

Simon Donner and Sandra Banholzer of the University of British Columbia in Vancouver, Canada, used historical sea surface temperature data to classify El Niño events into three groups on the basis of the location of ocean warming: the eastern Pacific, the central Pacific and a mixture of both. They then compared their results with three data sets of global temperatures. Although El Niños are commonly associated with warming, the duo found that only the more powerful eastern Pacific El Niño was linked to higher global temperatures.

These varying El Niño effects could explain some of the temperature trends seen in the Pacific Ocean since the late 1880s, such as periods of both accelerated and slow warming.

Geophys. Res. Lett. http://doi.org/r6z (2014)