Very early warning signal for El Ni\~no in 2020 with a 4 in 5 likelihood

The El Ni\~no Southern Oscillation (ENSO) is the most important driver of climate variability and can trigger extreme weather events and disasters in various parts of the globe. Recently we have developed a network approach, which allows forecasting an El Ni\~no event about 1 year ahead. Here we communicate that since 2012 this network approach, which does not involve any fit parameter, correctly predicted the absence of El Ni\~no events in 2012, 2013 and 2017 as well as the onset of the large El Ni\~no event that started in 2014 and ended in 2016. Our model also correctly forecasted the onset of the last El Ni\~no event in 2018. In September 2019, the model indicated the return of El Ni\~no in 2020 with an 80% probability.