From Mashable (Andrew Freedman):
…the climate phenomenon known as El Niño has turned its intensity up to 11 in recent weeks, directing a firehose of moisture at the Southwestern U.S., including drought-plagued California…
This week, forecasters at the Climate Prediction Center in Maryland announced the ongoing El Niño was just as strong as the 1997-98 event — which was the strongest such event on record since reliable data began in 1950. That’s based on sea surface temperature departures from average in a particular area of the tropical Pacific Ocean, known as the “Nino 3.4 region” (other indices using atmospheric measurements actually show this event to be slightly stronger than the 1997-98 event).
Yet this El Niño is not like the 1997-98 event, nor is it all that similar to the other huge El Niño of the past several decades, which occurred in 1982-83. For one thing, the atmosphere and ocean system are doing some strange things across the Pacific Ocean, compared to what one might expect during a “typical” El Niño event.
For example, the western equatorial tropical Pacific Ocean has much milder water than would typically be seen during such an event, and the east-to-west trade winds blowing across the world’s largest ocean have not completely relaxed or reversed, as they often do during a strong El Niño.
In other words, if you look up El Niño in a climatology textbook, you’d see marked differences between the classic maps illustrating a strong event, and this one.
“While certain measures and certain indices and variables we look at at certain times may look like 1997-98… I think every El Niño expert is looking at this and saying ‘whoa, what a unique animal we have here,'” said Michelle L’Heureux, a climate forecaster and El Niño specialist at the Climate Prediction Center.
But most of all, this El Niño is taking place against the backdrop of global warming, meaning it is occurring at a time when the oceans are hotter and the air is milder and laden with more moisture, on a global basis, than it has ever been before in human history.
During 2015, global ocean temperatures repeatedly set all-time high temperature records and then exceeded them the month later. Specifically, parts of every major ocean basin were record warm during much of 2015. In November, the most recent month for which such data is available, the global sea surface temperature was the highest on record for that month, surpassing the previous record set in 2014 by 0.36 degrees Fahrenheit, or 0.20 degrees Celsius.
The average global sea surface temperature for the year-to-date was the highest for January–November in the 136-year period of record, at 1.30 degrees Fahrenheit, or 0.72 degrees Celsius, above average, surpassing the previous record set last year by 0.16 degrees Fahrenheit, or 0.09 degrees Celsius. It’s likely that scientists will announce within the next week that 2015 featured the warmest oceans of any year on record. This is due in part to El Niño, but largely manmade global warming.
While El Niño can account for an unusually mild Pacific Ocean, for example, it cannot account for the fact that parts of every major ocean basin were record warm in August and for much of 2015. It also cannot account for the rapid accumulation of ocean heat well below the surface that has been taking place.
Daniel Swain, a climate scientist at Stanford University, told Mashable that the eastern Tropical Pacific Ocean is warmer right now at this time of year than it has ever been, and this has a big effect on the weather in the midlatitudes.
No El Niño event is the same, Swain said, but since the last supercharged-El Niño ended in 1998, there has been more than a decade of global warming. “This record event is evolving in a different climate context than any of the events that we’ve previously observed,” he said.
This doesn’t mean that we have no idea what this El Niño will bring. Case in point: The forecast for a wet mid-to-late winter in California, which appears to be panning out. But it does mean that, increasingly, we should expect the unexpected.
“El Niño is still El Niño, but it’s a different El Niño,” Swain said.
