#2: Pacific decadal variability plays an important role determining the number of El Niño events: During positive decadal phases, more El Niño events occur.
ALT Occurrence of different types of El Niño. Observed occurrence of EP and CP El Niño events according to Freund et al. (2019) during the instrumental period (1870–2018). Insets show the event occurrence frequencies during PDV positive phases (upper inset) and PDV positive phases (lower inset) based on shaded observed periods of PDV based on TPI index (Henley et al. 2015).
#1 : Models with a projected La Niña–like mean-state warming pattern show a tendency toward more EP but fewer CP events compared to models with an El Niño–like warming pattern.
ALT Trends and changes of the ZSG index smoothed by a 7-yr running mean following Kohyama et al. (2017) and the TPI index in observations (HadISST, 1870–2016) and CMIP models in the future scenario runs RCP8.5 and SSP5-8.5 until 2100. Two selected models from the CMIP5 and CMIP6 phase are shown that represent El Niño/La Niña–like warming trends estimated by the least squares best-fit trend line in the future scenario run. Shading highlights observed periods of positive/negative PDV phases based on the TPI index.
This breaks not only the longest run of continuous dry conditions in the instrumental record going back to 1900, but also the long-term paleo record going back to 1600
Using coral records, we show that the number of Central Pacific El Nino events has increased by the end of the 20th century, with fewer but stronger eastern Pacific El Niño events youtu.be/jJhLWW2Eguc
El Niño is one of the most important weather phenomena on Earth & comes in 2 types: warming occuring in the central Pacific vs strong traditional El Niño in the Eastern Pacific. How El Niño will behave with future climate change is an open question. rdcu.be/bAxOG