The frequency of extreme El Niño events is projected to increase for a further century after global mean temperature is stabilised at 1.5°C above pre-industrial levels.
Research published in Nature Climate Change by an international team shows that if warming were halted to the aspirational 1.5°C target from the Paris Agreement, the frequency of extreme El Niño events could continue to increase, owing to a continuation of faster warming in the eastern equatorial Pacific.
CSIRO researcher and lead author Dr Guojian Wang said the growing risk of extreme El Niño events did not stabilise in a stabilised climate.
‘Currently the risk of extreme El Niño events is around five events per 100 years,’ Dr Wang said. ‘This doubles to approximately ten events per 100 years by 2050, when our modelled emissions scenario (RCP 2.6) reaches a peak of 1.5°C warming.
‘After this, as faster warming in the eastern equatorial Pacific persists, the risk of extreme El Niño continues upwards to about 14 events per 100 years by 2150. This result is unexpected and shows that future generations will experience greater climate risks associated with extreme El Niño events than seen at 1.5°C warming.’
Director of the Centre for Southern Hemisphere Oceans Research and report co-author Dr Wenju Cai said that this research continues important work on the impacts of climate change on the El Niño-Southern Oscillation which is a significant driver of global climate.
‘Extreme El Niño events occur when the usual El Niño Pacific rainfall centre is pushed eastward toward South America, sometimes up to 16,000 kilometres, causing massive changes in the climate. The further east the centre moves, the more extreme the El Niño.
‘This pulls rainfall away from Australia, bringing conditions that have commonly resulted in intense droughts across the nation. During such events, other countries such as India and China have experienced extreme events with serious consequences.’