I wanted to write "who can forget the El Nino of 2015-2016?" until I thought of today's dreaded Memory Hole. Let's start again. Do you remember the devastating El Nino of 2015-2016. If you do, you might be surprised that it's expected to return before 2017 is out.
We had a brief interlude of El Nino's nasty step-sister, La Nina, that brought drought-quenching relief to California, but that lasted about six months and then - poof. Still it had been thought we might have an extended ENSO-neutral stretch of breathing room for a couple of years or more. Apparently not.
The World Meteorological Organization (WMO) said on Friday that a new El Niño was 50-60% likely before the end of 2017. “Memories are still fresh of the powerful 2015-2016 El Niño which was associated with droughts, flooding and coral bleaching in different parts of the world and which, combined with long-term climate change, led to the increase of global temperatures to new record highs in both 2015 and 2016,” said Maxx Dilley, director of WMO’s climate prediction and adaptation division.
It is unusual for El Niño conditions to return so swiftly, said Tim Stockdale, principal scientist at the European Centre for Medium-range Weather Forecasts(ECMWF), one of the leading prediction centres around the world and which contributed to the WMO forecast. “Normally we would expect a longer interval before another warming. But, having said that, El Niño variability is really rather irregular.”
Another concern is that the variation in El Niño over decades may be switching to a new, hotter phase. “For the last decade, the tropical Pacific has tended to be on the cold side, and that has helped keep global temperatures down. With this warming coming back so soon, it makes you wonder if the decadal trend is a bit more on to the positive side,” said Stockdale. “Obviously if that were sustained over the next five to 10 years, it would make the global warming signal stand out more strongly than it has done over the past decade.”
Here's a good animation to explain El Nino from Britain's Met Office.