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The National Oceanic and Atmospheric Administration (NOAA) reports that 2014 was the worst year for coral bleaching around the Florida Keys since the 1997-1999 period in which a major El Niño was followed by a major La Niña.

Source: NOAA

Source: NOAA

El Niño refers to a weather phenomenon characterized by above-average ocean temperatures in the Equatorial Pacific. This year saw no major El Niño activity, though NOAA says that there is a 65 percent chance of El Niño conditions throughout the Northern Hemisphere winter and into spring 2015. The unusually severe coral bleaching that occurred around the Florida coastline is seen as evidence that an El Niño is gearing up.

“[In] 2010 we had a mild El Niño, but yet we had the very same pattern of global bleaching going on—not as severe, but a lot of places were hit very badly,” Mark Eakin, NOAA’s Coral Reef Watch Coordinator, explained in a Diving Deep podcast. “We’re concerned about this El Niño because of the warming we’re already seeing…even a small El Niño is likely to cause a lot of bleaching in 2015.”

Warming ocean waters is one example of negative climate change that is already impacting the planet. Coral are living organisms that share a symbiotic relationship with the algae that live inside them. The algae absorb the light of the sun and photosynthesize, providing food for the coral. Sustained heat stress, however, causes corals to expel their algae, simultaneously leaving them paler and more prone to disease. If water temperatures do not return to normal, a coral can die after about eight weeks without its symbiotic algae.

In late September of this year, significant heat stress was recorded in the northwestern Hawaiian islands. Researchers observed major bleaching around the Lisianski atoll about 1,000 miles northwest of Honolulu, with 35 percent of coral sites showing evidence of bleaching and one shallow area exhibiting as much as 90 percent bleaching.

coralAccording to Planet Expert Nick Fash, both ocean warming and ocean acidification pose threats not only to coral reefs but to the entire marine ecosystem. “[C]oral reefs are living organisms themselves,” he said in a recent interview, “but they provide structure and habitat for thousands of other organisms. So even a slight decline in coral reef health can have a tremendous effect that will cascade throughout our oceans.”

In November, NOAA reports that anomalies in sea surface temperatures increased across the central and eastern equatorial Pacific. These anomalies will increase further if El Niño begins in earnest next year.

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