The extreme El Nino of 2015-2016 and the end of global warming hiatus

Slower rates of increase in global mean surface temperature (GMST) after 2000, dubbed global warming hiatus, recently gave way to a rapid temperature rise. This rise coincided with persistent warm conditions in the equatorial Pacific between March 2014 and May 2016, which peaked as the 2015 extreme El Nino. Here we show that the El Nino-Southern Oscillation (ENSO) tightly controls interannual variations in atmospheric heating rate in the tropics (r > 0.9), allowing us to construct a simple, physically based model of GMST variations that incorporates greenhouse gas emissions, ENSO forcing, and stratospheric sulfate aerosols produced by volcanoes. The model closely reproduces GMST changes since 1880, including the global warming hiatus and the subsequent temperature rise. Our results confirm that weak El Nino activity, rather than volcanic eruptions, was the cause of the hiatus, while the rapid temperature rise is due to atmospheric heat release during 2014-2016 El Nino conditions concurrent with the continuing global warming trend.