Warming Oceans Behind Historic Coral Bleaching Events: Scientists

Scientists declared Thursday that the planet is experiencing the third-ever global coral bleaching event on record. As climate change brings warmer waters, vital marine ecosystems are at increasing risk.

Compounded by long-term climate change, events like El Nino pose deadly threats to coral reefs as they succumb to severe or long-term bleaching that degrades and erodes their structures--which in turn provides less shoreline protection from storms and fewer habitats for ecologically and economically critical marine life, the National Oceanic and Atmospheric Association (NOAA) announced.

"The coral bleaching and disease, brought on by climate change and coupled with events like the current El Nino, are the largest and most pervasive threats to coral reefs worldwide," said Mark Eakin, NOAA's Coral Reef Watch coordinator. "As a result, we are losing huge areas of coral across the U.S., as well as internationally."

"What really concerns us is that this event has been going on for more than a year, and our preliminary model projections indicate it's likely to last well into 2016," Eakin said.

U.S. reefs are being hit disproportionately hard, particularly in Hawaii, where the effects are intensifying and expected to worsen over the next month. However, NOAA estimates that by the end of 2015, nearly 95 percent of all American coral reefs will have been exposed to bleaching conditions. Moreover, those conditions may last into the next year.

Also at high risk are reefs surrounding Haiti, the Dominican Republic, Puerto Rico, and the U.S. Virgin Islands. Bleaching in the Indian and southeastern Pacific Oceans is also expected to continue and grow with the arrival of El Nino.

As Peace and World Security professor Michael T. Klare explains in an article published Thursday, "Although such reefs make up less than 1% of the Earth's surface area, they house up to 25% of all marine life. They are, that is, essential for both the health of the oceans and of fishing communities and those who depend on fish for a significant part of their diet."

Citing the Intergovernmental Panel on Climate Change (IPCC), Klare writes, "'This irreversible loss of biodiversity...will have 'significant consequences for regional marine ecosystems as well as the human livelihoods that depend on them.'"

The two previous global coral bleaching events occurred in 1998 and 2010. But, as University of Queensland professor and Global Change Institute director Ove Hoegh-Guldberg told the Guardian, this one is poised to be "the worst coral bleaching event in history."

"The development of conditions in the Pacific looks exactly like what happened in 1997. And of course, following 1997, we had this extremely warm year, with damage occurring in 50 countries at least and 16% of corals dying by the end of it," Hoegh-Guldberg explained. "Many of us think this will exceed the damage done in 1998."

So what can be done? According to NOAA, it's the very solution economic and environmental activists have long called for: acting locally and thinking globally.

"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, NOAA Coral Reef Conservation Program acting program manager. "To solve the long-term, global problem, however, we need to understand better how to reduce the unnatural carbon dioxide levels that are the major driver of the warming."

"We need to act locally and think globally to address these bleaching events," Koss said.