Over-projected Pacific warming and extreme El Ni?o frequency due to CMIP5 common biases

Extreme El Ni?o events severely disrupt the global climate, causing pronounced socio-economic losses. A prevailing view is that extreme El Ni?o events, defined by total precipitation or convection in the Ni?o3 area, will increase 2-fold in the future. However, this projected change was drawn without removing the potential impacts of Coupled Model Intercomparison Project phase 5(CMIP5) models’ common biases.Here, we find that the models’ systematic biases in simulating tropical climate change over the past century can reduce the reliability of the projected change in the Pacific sea surface temperature(SST) and its related extreme El Ni?o frequency. The projected Pacific SST change, after removing the impacts of 13 common biases, displays a ‘La Ni?a-like’ rather than ‘El Ni?o-like’ change. Consequently, the extreme El Ni?o frequency, which is highly linked to the zonal distribution of the Pacific SST change, would remain mostly unchanged under CMIP5 warming scenarios. This finding increases confidence in coping with climate risks associated with global warming.