The report says ‘the possible return of El Niño this year would present a unique situation’. Is there still excess heat in the system as sunspots go further into ‘quiet mode’?
The path to another round of El Niño in 2017 appears to be shortening, as tropical Pacific Ocean waters have been warming at a substantial rate. Several models suggest that El Niño could be comfortably in place as early as May.
Weather forecasters have been eyeing for a couple of months a possible return this year of El Niño, which normally comes around every two to seven years and last occurred in 2015/16.
The El Niño-Southern Oscillation is one of the most widely followed long-term indicators of climate, as both its warm and cool phases can trigger varying effects on weather patterns globally.
El Niño, which is associated with warmer-than-normal sea surface temperatures (SSTs) along the equatorial Pacific, is known to bring volatile weather to some parts of the world and is closely watched by agricultural and energy markets. Some notable impacts include droughts in Southeast Asia and heavy rains and erosion along the Pacific coasts of North and South America.
La Niña, the cool phase of ENSO, just concluded its six-month run last month. In the last several weeks, remnants of the colder waters have been all but eliminated.
In the week centered on Feb. 22, the SST anomaly was positive 2.3 degrees Celsius in the Niño 1+2 region, the easternmost of the four Niño regions, directly off the coast of Peru. Warming in this region sometimes precedes the onset of El Niño.
To put this into perspective, since weekly record-keeping began in 1990, the only other instances that featured warmer SST anomalies in this region occurred during the mega-El Niños of 2015/16 and 1997/98, as well as the moderate-to-strong El Niño in early 1992.
The week centered on Jan. 25, 2017, also recorded a 2-degree anomaly, so the latest value is not necessarily an outlier. But if this trend eventually translates into a full-on El Niño later in the year, the outcome would be unprecedented.
A record-breaking El Niño surfaced in mid-2015 and lasted through early 2016, after which SSTs dropped off and gave way to the relatively weaker La Niña event to cap off the year.
But following the previous occurrences of strong El Niño – 1997/98, 1982/83, 1972/73 – the warm cycle did not appear again until three or four years later. So the possible return of El Niño this year would present a unique situation against which there is not much comparable data.
The report continues here.