Extreme temperatures in Southeast Asia caused by El Ninõ and worsened by global warming

In April 2016, southeast Asia experienced surface air temperatures (SATs) that surpassed national records, exacerbated energy consumption, disrupted agriculture and caused severe human discomfort. Here we show using observations and an ensemble of global warming simulations the combined impact of the El Ninõ/Southern Oscillation (ENSO) phenomenon and long-term warming on regional SAT extremes. We find a robust relationship between ENSO and southeast Asian SATs wherein virtually all April extremes occur during El Ninõ years. We then quantify the relative contributions of long-term warming and the 2015-16 El Ninõ to the extreme April 2016 SATs. The results indicate that global warming increases the likelihood of record-breaking April extremes where we estimate that 29% of the 2016 anomaly was caused by warming and 49% by El Ninõ. These post-Ninõ Aprils can potentially be anticipated a few months in advance, and thus, help societies prepare for the projected continued increases in extremes.