The third global coral bleaching event is underway, having begun in the summer of 2014 in the north Pacific ocean and continuing to the south Pacific ocean and Indian ocean this year, scientists from the National Oceanic and Atmospheric Administration announced Thursday.
Hawaii is currently experiencing widespread coral bleaching. Corals in the Caribbean, particularly in Puerto Rico and the U.S. Virgin Islands, are also under threat as warmer waters creep in.
"Last year's bleaching at Lisianski Atoll was the worst our scientists have seen," said Randy Kosaki, NOAA's deputy superintendent for the monument, adding that the bleaching killed one-and-a-half square miles of reef.
"This is only the third time we've seen what we would refer to as a global bleaching event, an event that causes mass bleaching in the Indian Ocean, the Pacific Ocean, and the Atlantic-Caribbean basin," Mark Eakin, head of NOAA's Coral Reef Watch, told The Washington Post.
The first two global bleaching events took place in 1998 and 2010, and both lasted for about a year, according to Eakin. However, the present global bleaching event is different.
"We're looking at a similar spatial scale of bleaching across the globe, but spanning across at least 2 years. So that means a lot of these corals are being put under really prolonged stress, or are being hit 2 years in a row," Eakin said. The present coral bleaching that begun in 2014 could last until 2016 based on projections, the NOAA noted.
The NOAA predicts that at least a third, or 38 percent, of the world's corals will die from bleaching by the end of 2015, affecting an estimated 4,633 square miles of coral reefs, according to Fox News.
In the U.S., NOAA projects that by the end of the year, about 95 percent of coral reefs will be exposed to severe environmental conditions that can cause bleaching.
"We need to act locally and think globally to address these bleaching events. Locally produced threats to coral, such as pollution from the land and unsustainable fishing practices, stress the health of corals and decrease the likelihood that corals can either resist bleaching, or recover from it," said Jennifer Koss, acting program manager for the NOAA Coral Reef Conservation Program.
Koss said reduction of "unnatural carbon dioxide levels that are the major driver of the warming" is necessary to address the global coral bleaching problem.
