The effects of climate change on the frequency of extreme El Nino events are investigated in a paper published online this week in Nature Climate Change.
El Nino is a natural climate variability feature that has worldwide effects. Extreme El Nino events cause global disruption of weather patterns and affect ecosystems and agriculture through changes in rainfall.
Wenju Cai and colleagues use climate models to show that a doubling in the occurrence of extreme El Nino episodes is caused by increased surface warming of the eastern equatorial Pacific Ocean. This area of the ocean warms faster than the surrounding waters, reducing sea surface temperature gradients, which results in the atmospheric convection zone shifts required for these extreme episodes to occur. These findings are in contrast to previous studies that found no consensus on El Nino change. The authors suggest that the increased frequency of these episodes will result in more frequent catastrophic weather events in the future.