Scientists Confirm Global Coral Bleaching Event for 2015

Image: Coral Bleaching in American Samoa


In collaboration with our partners the National Oceanic and Atmospheric Administration (NOAA, The University of Queensland, and Reef Check, we today confirmed a “global coral bleaching event” is underway. Increased ocean temperatures due to climate change, combined with the warming effects of an El Niño pattern and a Pacific warm water mass referred to as “The Blob”, are driving temperatures to record levels and threatening to severely deplete the coral reef ecosystems that support fish habitats, shoreline protection and coastal economies.


The announced global coral bleaching event, only the third of its kind in recorded history, is expected to impact approximately 38% of the world’s coral reefs by the end of this year and kill over 12,000 square kilometers (4,633 square miles) of reefs, according to NOAA. Although reefs represent less than 0.1 percent of the world’s ocean floor, they help support approximately 25 percent of all marine species. As a result, the livelihoods of 500 million people and income worth over $30 billion are at stake.


A summary of our findings, as well as new information about coral bleaching and never before seen high-resolution imagery, has been specially developed to explain the event:



Warming Causing Ocean Ecosystem Destruction


Oceans absorb approximately 93 percent of the increase in the earth’s heat from climate change, making them one of the most visual indicators of the issue – particularly when change is revealed through dramatic episodes like global coral bleaching. During a bleaching event, corals expel the golden-brown algae that grow within their body tissue, exposing their white skeletons—hence the term “bleaching.” If the ocean temperature remains higher than the seasonal norm for a number of weeks the corals can die en masse, causing the loss of some corals that may be decades to centuries old.



Bleak Outlook for Corals


Caused by an unusual warming of the Northern Hemisphere oceans, 2015 has now seen coral bleaching occurring in reefs in the northern Pacific, Indian, equatorial Pacific, and western Atlantic Oceans. Recorded for the first time in 1998 and again in 2010, global coral bleaching is designated when all three major ocean basins (Indian, Pacific, Atlantic) have recorded widespread bleaching episodes across multiple reefs spanning 100 kilometers (62 miles) or more.


The first two global bleaching events were observed as the result of a chain of warming events caused by El Niño cycles and increased ocean temperatures due to climate change. This year’s widespread bleaching shows the same characteristics – warmer-than-usual water temperatures combined with what could potentially be the strongest El Niño ever recorded.


Coral bleaching in the Pacific Ocean began in mid-2014 and has not stopped since, moving around as warm conditions have enveloped different regions. Similar to past global coral bleaching events, this year’s phenomenon is greatly intensified by climate change and, with forecasts of the El Niño remaining strong until early 2016, the worst may be yet to come.



Activating the “Rapid Response” Team


During the previous global coral bleaching event of 1998, the world simply didn’t have the technology, understanding or teams in place to reveal and record such events properly. However recent advancements in bleaching prediction and near-real-time satellite monitoring by NOAA has allowed us to deploy a rapid response team to capture images of coral bleaching as it happened. By documenting the various stages of the bleaching process, our scientists are gathering in-depth insight into the marginal and cumulative impacts of this event and building on more than 20 years of data in published studies collected from bleaching episodes worldwide.