El Niño, just in time for Christmas!

Global SSTA's
How unusual are December’s ocean temperatures? The eastern equatorial Pacific is unusually hot (yellow/red), showing the signature of an El Niño (earth.nullschool.net sea surface temperature anomalies, 12/23/15).

Fishermen off the coast of Peru have long noticed a warm current that appeared in the Pacific around Christmastime, and dubbed this phenomenon “El Niño,” after the young Christ.  Today, “El Niño” refers to the pattern of unusually warm waters in the equatorial Pacific, which appears every 2-7 years and peaks in December.

Now, Christmas is almost upon us, and this year’s El Niño is expected to peak soon.

This year’s El Niño began with a weak start.  The atypical pattern of surface temperatures that began in March 2015 earned it the moniker of “El Weirdo.” It’s always difficult to predict an El Niño more than a few months in advance, so researchers were unsure that this El Niño would last longer than a few weeks.

Surprise!  Since then, the eastern Pacific has warmed even further, turning the 2015 El Niño into one of the strongest on record, second only to the one in 1997.  You can explore current global ocean temperature anomalies at one of my favorite sites, here.

How does 2015's El Niño compare to previous events? The most recent data (September-November average) show that 2015's El Niño is the second strongest since 1950. (Oceanic Nino Index, SSTA in 5N-5S, 120-170W, accessed 12/23/15).
How does 2015’s El Niño compare to previous events? The most recent data suggest that 2015’s El Niño could be the second strongest since 1950. (September-November average, Oceanic Nino Index, SSTA in 5N-5S, 120-170W, accessed 12/23/15).

El Niño is changing temperature and precipitation patterns worldwide.  In the next few months, El Niño is predicted to make the northern U.S. unusually warm (as my dad put it, “El Niño is bad news for northeast skiers”) and bring additional rainfall to the southern states.  Check out the predicted impacts for your region here.

But El Niño impacts aren’t restricted to the U.S.  In October, scientists at the National Oceanic and Atmospheric Administration declared the beginning of a global coral bleaching event, the third on record.  Warm waters can stress corals, forcing out their symbiotic algae, bleaching the corals and effectively starving them.  In 1997-1998, the largest El Niño on record caused a bleaching event that killed 16 percent of the world’s coral reefs.  A similar event is now underway.

El Niño also strengthens the Pacific hurricane season, and weakens the Atlantic one.  Since Pacific westerlies weaken during El Niños, large storms can form without being torn apart by strong winds.  October’s Hurricane Patricia, the strongest storm ever measured, probably formed because of unusually warm waters and weaker westerlies caused by El Niño.

That’s just the tip of the iceberg.  There are whole books on the impacts of El Niño. Hopefully, though, this post has convinced you of three things:

El Niño is big, it’s important, and it’s happening now.