Researchers at the National Oceanic and Atmospheric Administration (NOAA) say that the conditions in the tropical Pacific now qualify to be considered El Niño. The phenomenon refers to warmer waters around the central Pacific, which influence the weather conditions of many countries along the ocean.
The NOAA announcement comes after atmospheric conditions shifted. For the region to be experiencing El Niño, three things need to happen: the surface of the ocean needs to be more than 0.5°C above the long-term average, this temperature needs to hold up for several seasons, and finally, the Walker atmospheric circulation needs to diminish. This means more rains need to happen over the central Pacific than in South-East Asia.
In the past month, researchers saw these changes in the atmosphere and, given that the ocean has been quite warm for a few months, the conditions for El Niño were met. Based on the forecasts, we shouldn’t expect a strong El Niño, like in 2016. Everything suggests that the one this year is going to be much weaker and less influential.
“Weak El Niño conditions mean that El Niño isn’t dominating the global circulation, and there is a lower probability of El Niño-related global temperature and precipitation effects through the next few months,” noted the NOAA announcement.
It's possible that El Niño this year is also much shorter. The current forecast has the chances of a continued El Niño after the spring below 50 percent. The reason for this is due to the complex and variable nature of the whole system (called El Niño-Southern Oscillation) during springtime. Predictions tend to do quite poorly before spring, but once May comes around, the prediction for the rest of the year makes a huge leap in accuracy.
The phenomenon of El Niño and its cooler counterpart La Niña have effects on the climate of the entire planet. Dry and wet seasons across the Pacific Rim are shaped by the El Niño-Southern Oscillation, as are temperature trends across the world. El Niño is also responsible for many of the barrier reef bleaching events along the ocean, including the Great Barrier Reef.