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Destructive global coral bleaching event expected to end, NOAA says

A new forecast from the National Oceanic and Atmospheric Administration (NOAA) indicates that the global coral bleaching event, which has jeopardized coral reefs around the world for the past three years, is nearly over.

In 2015, NOAA declared the third-ever global coral bleaching event was ongoing as record ocean temperatures, attributed to climate change and a strong El Niño, caused debilitating effects to corals.

NOAA’s forecast shows that widespread bleaching is no longer underway in the Atlantic, Pacific or Indian oceans. However, scientists will still monitor sea surface temperatures over the next six months to confirm the bleaching event has concluded.

Many of the world’s most colorful underwater landscapes have turned white, including Australia’s Great Barrier Reef, and face a long road to recovery.

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This May 2016 photo provided by NOAA shows bleaching and some dead coral around Jarvis Island, which is part of the U.S. Pacific Remote Marine National Monument. (Bernardo Vargas-Angel/NOAA via AP)

“This global coral bleaching event has been the most widespread, longest and perhaps the most damaging on record,” C. Mark Eakin, NOAA’s Coral Reef Watch coordinator, said in a statement. “NOAA is working with scientists, resource managers and communities around the world to determine what the true impacts of this event will be on coral reefs.”

The bleaching event first began in the North Pacific in summer 2014, before expanding to the South Pacific and Indian oceans in 2015. NOAA stated that more than 70 percent of tropical coral reefs around the world have experienced prolonged temperatures that can cause bleaching.

A recent analysis of World Heritage Properties found that only four of 29 locations had no significant heat stress during this event. These areas include the Brazilian Atlantic Islands off the east coast of Brazil and the Socotra Archipelago in Yemen.

In the United States, severe bleaching was reported in Florida and Hawaii. And while the event appears to be subsiding, experts say some corals are not out of the woods just yet. NOAA’s four-month coral bleaching heat stress outlook still shows a risk for Hawaii, Florida and the Caribbean.

While enduring stressful environmental conditions, such as record high water temperatures, corals expel the symbiotic algae living in their tissues, which causes them to turn white. This allows them to lose their major source of food and become more susceptible to disease.

When healthy, coral reefs serve as habitats for marine life and can even protect shores from storms. The United Nations Educational, Scientific and Cultural Organization (UNESCO) estimates the social, cultural and economic value of reefs at $1 trillion.

Jennifer Koss, director of NOAA's Coral Reef Conservation Program, said coral reefs are not beyond help and there are several ways to improve the population and health of corals.

"What this largely means is improving the health of the marine environment," Koss told AccuWeather in an email. "NOAA works to improve water quality by reducing and mitigating pollutants, sediment, excess nutrients and toxins that come from the land via stormwater runoff and sewers."

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Bleached coral in Kaneohe Bay, Hawaii. (Photo/Catlin Seaview Survey)

Other ways to improve the quality of the ecosystem include ensuring fishing is done sustainably by making sure gear and anchors don't physically impact the reefs, Koss explained.

Recovery rates for corals are dependent on the species of coral in question, how severe the bleaching was, if the area is overfished, the amount of pollution in the water and the amount of time between stress events.

"There have been estimates that an entire reef takes at least five years to recover from a bleaching event," Koss said.

The previous two global coral bleaching events occurred in 1998, during a strong El Niño, and 2010. Looking forward, experts believe there is a strong likelihood that another global bleaching event could happen.

"While large El Niño events were required to cause global bleaching events, much smaller events are likely to do so now," Koss said, adding that tropical waters have warmed significantly in the last three years.

"On average, El Niño returns every three to seven years, suggesting the next global bleaching event may come soon," she said.