Jul 24, 2017

Continued increase of extreme El Nino frequency long after 1.5°C warming stabilization

Guojian Wang, Wenju Cai, Bolan Gan, Lixin Wu, Agus Santoso, Xiaopei Lin, Zhaohui Chen, Michael J. McPhaden
Nature Climate Change
  • States that the Paris Agreement aims to constrain global mean temperature (GMT) increases to 2 °C above pre-industrial levels, with an aspirational target of 1.5 °C
  • States that however, the pathway to these targets and the impacts of a 1.5 °C and 2 °C warming on extreme El Niño and La Niña events—which severely influence weather patterns, agriculture, ecosystems, public health and economies—is little known
  • Demonstrates, by analysing climate models participating in the Climate Model Intercomparison Project’s Phase 5 under a most likely emission scenario, that extreme El Niño frequency increases linearly with the GMT towards a doubling at 1.5 °C warming
  • Finds that this increasing frequency of extreme El Niño events continues for up to a century after GMT has stabilized, underpinned by an oceanic thermocline deepening that sustains faster warming in the eastern equatorial Pacific than the off-equatorial region
  • Results indicate little to no change in the frequency of extreme La Niña events under 1.5 °C or 2 °C warming