Globally Warming Oceans Are Killing Coral Reefs

A before and after image of the bleaching in American Samoa. The first image was taken in December 2014. The second image was taken in February 2015. Credit: XL Caitlin Seaview Survey

The third-ever global coral bleaching event is killing coral reefs and the many creatures that rely upon them worldwide. Hot global temperatures are heating up the oceans, and are compounded by a strong El Niño pattern, causing stresses, vulnerability, and death to corals that cannot withstand the hotter temperatures. In the absence of significant mitigation to fossil-fueled global warming, coral reefs and the abundant reef-dependent sea life are falling casualty to inaction.

“The coral bleaching and disease, brought on by climate change and coupled with events like the current El Niño, are the largest and most pervasive threats to coral reefs around the world,” 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 has us concerned is 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.”

Global bleaching events have coincided with the increasingly high temperatures caused by global warming. Chart Credit: NASA/GSFC/Earth Observatory, NASA/GISS

Coral bleaching is one of the most visually obvious impacts of climate change, as the frequency and severity of such outbreaks corresponds with the warming of the earth’s climate. The current coral bleaching event is the third such global event, with the first occurring in 1997-98 and the second occurring in 2010. These years were some of the hottest years on land too. 2014 was the hottest year on record and 2015 is so far on track to be even hotter. 2010 was the second hottest year ever, and 1998 was the fourth hottest year ever.

The reefs off the Southeast coast are no exception to this tragic event. The Fort Lauderdale Sun Sentinel reported last month that corals from the Keys to offshore Palm Beach County are turning chalk-white and dying. Particularly troubling is that some of these coral communities are highly resilient, having survived 200 to 300 years of stressors, yet are now succumbing.”The fact that they are dying now after living hundreds of years, may indicate that their surroundings are much more stressful than ever before,” said Brian Walker, research scientist at Nova Southeastern University’s Halmos College of Natural Sciences and Oceanography. Sadly, the effects from coral die-off events are largely permanent.

Fortunately, the reefs off of Georgia’s coast do not seem to be affected at this point. Dr. Scott Noakes, with the Center for Applied Isotope Studies at the University of Georgia, who studies Gray’s Reef, reports that since the organisms at Gray’s Reef endure considerable temperature, carbon dioxide, and pH swings annually, the benthic community is hardier than what you would find in more tropical water, where seasonal temperature variation is minimal.

As of this month, we have had 366 consecutive months of higher than average temperatures. With no respite from our globe’s heating in sight, we need to act strongly to cut greenhouse as emissions by transitioning to clean energy. The upcoming United Nations climate conference in Paris in late November-early December will pose a pivotal opportunity for nations around the globe to come together to help save our common resources, such as the wonderful ocean life sustained by coral reefs. As Pope Francis has recently made clear to the world, saving our common home, Earth, is of the highest order of moral imperatives.

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