Many global impacts already
El Niño events, while simply descriptions of ocean temperatures in the tropical Pacific and not storms, have ripple effects on weather patterns all over the world.
“Severe droughts and devastating flooding being experienced throughout the tropics and sub-tropical zones bear the hallmarks of this El Niño, which is the strongest for more than 15 years,” said World Meteorological Organization (WMO) Secretary-General Michel Jarraud in a news release.
The WMO published a long list of many harmful weather impacts for which this El Niño has been implicated, including coral bleaching and the most active season for intense tropical cyclones in the Northern Hemisphere on record, both due to historically warm ocean waters.
It also linked El Niño with drought in South East, Asia which has lead to one of the worst wildfire outbreaks in Indonesia on record.
Not all impacts from El Niño have been harmful. For example, it introduced wind shear in the tropical Atlantic which has depressed hurricane activity that might impact North America and may already be increasing precipitation in California, which is suffering from a historic drought.
This El Niño is operating in a warmer world in which forecasters have no prior experience predicting its effects.
“This event is playing out in uncharted territory,” Jarraud said. “Our planet has altered dramatically because of climate change, the general trend towards a warmer global ocean, the loss of Arctic sea ice and of over a million square kilometers of summer snow cover in the northern hemisphere.”
“So this naturally occurring El Niño event and human induced climate change may interact and modify each other in ways which we have never before experienced,” he said.
“Even before the onset of El Niño, global average surface temperatures had reached new records. El Niño is turning up the heat even further,” Jarraud added.
Comparing this year’s El Niño vs. 1997-1998, and what it portends
While today’s unsurpassed ocean temperature measurement in the central tropical Pacific made history, it is too soon to know if this toasty temperature reading is just a blip or a signal. In order for this El Niño to officially pass 1997-1998’s event as the strongest on record, the warm waters would need to be sustained near these level for three months.
“A week of sea surface temperature-only data isn’t enough to say this is a record,” said NOAA climate analyst Michelle L’Heureux in an email.
Forecasters expect strong El Niño levels to persist through the winter, but it may be peaking now and about to begin a gradual decay. However, the event’s recent and projected intensity may be enough for this event to surpass 1997-1998.
“Judging from the trajectory of SST anomalies … it is likely that one of the late-year three-month average … sea surface temperature values in 2015 will end up upending 1997’s record warmth and claim for the 2015 the title as strongest El Niño event on record,” wrote Weather Underground meteorologist Jeff Masters.
Every El Niño has its own signature and, so far, what sets this one apart is the amount of warm water it has generated across a vast expanse of the Pacific – spanning both the eastern and central part of the ocean basin. While it hasn’t been as intense in the eastern tropical Pacific as 1997-1998, its warm waters have extended farther west.
“So, in terms of the eastern Pacific, this event is weaker than 1997, but in terms of the central Pacific, the present event is stronger,” said Paul Roundy, a professor of atmospheric science at the University of Albany.
Phil Klotzbach, a tropical weather researcher from Colorado State University, says a powerful eastward push of water known as a Kelvin wave may lead to some warming in the eastern Pacific over the next few weeks.
The implications of warm water covering such a vast area of the Pacific in terms of weather patterns in the U.S. are unclear.
Sometimes El Niño events which have their warmest waters in the central rather than eastern Pacific favor less precipitation in California and colder conditions in the Northeast U.S. than events with warmer water to the east. But researchers aren’t convinced this event will behave like a central Pacific El Niño, sometimes described as a Modoki event.
“Although it has large sea surface temperature anomalies across the central basin, it is NOT a central Pacific El Niño event,” Roundy said. “The present circulation response pattern and model forecasts agree that circulation outcomes are likely to be more like strong east Pacific events, because convection is aligned well east of the dateline.”
Klotzbach along with two climate researchers at NOAA’s Climate Prediction Center, Jon Gottschalck and Stephen Baxter, said they agreed with Roundy’s view via email.
Jason Furtado, a professor of meteorology at the University of Oklahoma, said while he concurred this El Niño is not a central Pacific event, the very warm waters observed there might mean the winter bears some of its characteristics. Furtado also cautioned El Niño “is but one ingredient for our winter climate – its interactions with other processes and climate patterns will also be important to monitor.”