Global Coral Bleaching 2014-2017: Status and an Appeal for Observations

In 2014, NOAA Coral Reef Watch wrote in Reef Encounter about the prospect for a 2014-15 El Niño (Eakin et al. 2014). While that El Niño never fully formed, it did help set off a multi-year global coral bleaching event -- the third ever documented. A subsequent 2015-16 strong El Niño formed, spreading and worsening the bleaching (Eakin et al. 2016), and a La Niña reared its head thereafter, further extending the event into 2017, as predicted. Multiple coral reef areas around the world experienced bleaching two or even three years in a row from 2014-2017. As of June 2017, the Third Global Coral Bleaching Event has most likely ended (National Oceanic and Atmospheric Administration (NOAA) 2017) but will remain the longest, most widespread, and possibly the most damaging coral bleaching event on record. It affected more reefs than any previous global bleaching event and was worse in some locales (e.g., Great Barrier Reef, Kiribati, Jarvis Island). Heat stress during this event also caused mass bleaching in several reefs that never bleached before (e.g., northernmost Great Barrier Reef).



Coral Reef Watch's Analysis of Current Thermal Conditions and Four-Month Outlook

NOAA Coral Reef Watch's most recent Coral Bleaching Alert Area is below. This figure shows the regions currently experiencing high levels of heat stress that can cause coral bleaching.


NOAA Coral Reef Watch's most recent Four-Month Coral Bleaching Heat Stress Outlook is below. This figure shows the distribution of the lowest heat stress levels predicted by at least 60% of the model ensemble members. In other words, there is a 60% chance that the displayed heat stress levels will occur.
   


NOAA Coral Reef Watch's satellite Coral Bleaching Alert Area below shows the maximum heat stress during the Third Global Coral Bleaching Event. Regions that experienced the high heat stress that can cause coral bleaching, from June 1, 2014 to May 31, 2017, are displayed. Alert Level 2 heat stress indicates widespread coral bleaching and significant mortality. Alert Level 1 heat stress indicates significant coral bleaching. Lower levels of stress may have caused some bleaching as well. More than 70% of coral reefs around the world experienced the heat stress that can cause bleaching and/or mortality during the three-year long global event.
   



NOAA Coral Reef Watch's (CRW) daily 5km satellite coral bleaching heat stress monitoring products indicate that in the eastern Pacific Ocean, cooler waters remain and all of CRW's 5km Regional Virtual Stations are experiencing low-level or no heat stress conducive to coral bleaching.

In the central equatorial Pacific, all of CRW's 5km Regional Virtual Stations have decreased to Bleaching Watch or No Stress status. This includes the Samoas, which suffered multiple weeks of Alert Level 2 heat stress in early to mid-2017, with confirmed reports of bleaching of both shallow and deeper corals.

The Main Hawaiian Islands (MHI), which observed record levels of bleaching in 2014 and static Alert Level 2 bleaching heat stress in October and November 2015, are at a Bleaching Watch. Alert Level 2 heat stress (associated with widespread coral bleaching and significant mortality) is expected in the next 1-4 weeks. The Northwestern Hawaiian Islands (NWHI), which sustained high, prolonged levels of bleaching heat stress in 2014 and some subsequent coral death, have returned to a Bleaching Watch. CRW continues to collect data from field partners, including Hawai'i's Eyes of the Reef (EOR) volunteer community reef monitoring program, concerning the extent and severity of coral bleaching and mortality in the MHI and NWHI since 2014 and throughout the Third Global Coral Bleaching Event.

Multiple of CRW's 5km Regional Virtual Stations in Micronesia have returned to Alert Levels 1 (associated with significant bleaching) and 2 bleaching conditions, after regions, such as the Republic of the Marshall Islands and the Eastern Federated States of Micronesia (FSM) registered Alert Level 2 bleaching heat stress for many weeks in early 2017. The Northern Mariana Islands have been experiencing Alert Level 2 bleaching conditions for more than a month; that severe stress is expected to remain for at least the next 5-8 weeks. Guam (which has been hit by severe bleaching now five years in a row) also continues at Alert Level 2 heat stress; those conditions are anticipated to remain for the next 5-8 weeks. The Western FSM, Eastern FSM, and Palau also are expected to remain at Alert Level 2 bleaching heat stress for at least the next 5-8 weeks. Wake Atoll remains at Alert Level 1, and the Marshall Islands have increased to a Bleaching Warning, with Alert Level 2 heat stress expected in 1-4 weeks' time. Alert Level 1 bleaching stress also is expected in the Gilbert Islands, Kiribati in 5-8 weeks' time and in Nauru in the next 9-12 weeks.

In Micronesia's Phoenix Islands, in particular, as noted in multiple articles below and by numerous news outlets worldwide, in Kiribati, persistent elevated ocean temperatures (as high as 31.4-degrees Celsius) in 2015-2016 killed most of the corals in the region. Photos taken by scientists surveying the reef damage, especially around Kiritimati (Christmas Island), where more than 80% coral mortality has been documented, are gruesome. The high bleaching heat stress in Kiribati was tied to the very strong El Niño that dissipated in late 2016 but whose effects lasted for multiple additional months in the southern hemisphere. It is estimated that only 1-5% of Kiribati's reefs will survive and recover from this severe bleaching heat stress event.

Severe heat stress (Alert Levels 1 and 2) persisted for many weeks in East Asia in summer 2016. Significant coral bleaching was reported in multiple reef areas, including Hainan Island, China, Northern Vietnam, Dongsha, Taiwan, and in the Ryukyu Islands, Japan - where extensive (over 90%) bleaching was observed in the region's largest coral reef (Sekiseishoko Reef) as of July 2016, resulting in 70% mortality. Now, with the arrival of Northern Hemisphere autumn, the severe Alert Level 2 heat stress that corals experienced in the Ryukyu Islands, Japan, Taiwan, and Vietnam in late summer 2017 has finally dissipated. Alert Level 2 bleaching stress remains in Hong Kong, China and Hainan Island, China but is expected to diminish in the next 1-4 weeks. CRW has been communicating with local coral reef management and research partners to determine the extent of the damage to the region's coral reefs during and since the Third Global Coral Bleaching Event.

In Southeast Asia, CRW's 5km Regional Virtual Stations are at a level of either Bleaching Watch or No Stress.

Coral bleaching heat stress continued to diminish throughout the Coral Triangle. However, a short burst of Alert Level 1 heat stress is expected again in the Eastern Philippines and Southern Philippines in 1-4 weeks' time (after the Philippines suffered severe Alert Levels 1 and 2 heat stress for much of June and July 2017). Short-lived Alert Level 1 bleaching stress also is expected in Sabah, Malaysia, North Sulawesi, Central Sulawesi and Gorontalo, East Kalimantan, West Papua, Maluku, Indonesia, and West Sulawesi within the next 5-8 weeks. Potentially more prolonged Alert Level 1 heat stress is expected in Papua New Guinea in 5-8 weeks' time and in the Solomon Islands in 9-12 weeks. CRW continues communicating with local field partners to try and assess the status of local reefs throughout the Coral Triangle impacted by severe bleaching heat stress during and since the Third Global Coral Bleaching Event.





As reported in multiple articles below and by news sources around the world, sustained, high ocean temperatures in early 2016 (especially in March) did significant damage to Australia's Great Barrier Reef (GBR). Per the Australian National Coral Bleaching Taskforce, the Australian Research Council Centre of Excellence for Coral Reef Studies, and the Great Barrier Reef Marine Park Authority, the event turned out to be the worst bleaching in the GBR's history. This was especially true in the northernmost portion of the GBR, which experienced massive die-offs of coral. A NOAA CRW co-authored Nature cover story on the 2016 GBR bleaching was published on March 15, 2017. Click here for additional information.

After multiple weeks of severe (Alert Levels 1 and 2) heat stress along much of the GBR, especially the central GBR, in March 2017 (the Reef's unprecedented, second consecutive year of confirmed mass bleaching), cooler waters finally arrived in the region in mid-April. All of CRW's 5km Regional Virtual Stations for the GBR region returned to a level of No Stress. CRW's near-real-time satellite monitoring and modeled predictions of environmental stress associated with the Third Global Coral Bleaching Event have been critical in helping local management and research partners plan effectual in-water and aerial surveys of the GBR, in both 2016 and 2017.

In mid-May 2017, cooler waters arrived along the western coast of Australia, in the Indian Ocean. Since that time, CRW's 5km Regional Virtual Stations throughout the region have been at a level of No Stress.





Bleaching heat stress developed again in early March 2017 in the Western Indian Ocean. However, since moderate bleaching was confirmed in only one area of the Indian Ocean in April 2017 - in Southwestern Madagascar - and not basin-wide, this provided the first hint that the the Third Global Coral Bleaching Event might be coming to an end. By mid-April 2017, CRW's 5km Regional Virtual Stations throughout the Western Indian Ocean region had returned to a level of No Stress.

It is important to note that even though widespread coral bleaching was not confirmed throughout the Indian Ocean in the first half of 2017, in the Middle East, severe Alert Level 2 bleaching heat stress was present throughout September 2017 in multiple coral reef areas, including in the Western Persian Gulf and Bahrain. As of early October 2017, a short burst of Alert Level 1 heat stress also is expected in the next few weeks in Aden, Yemen, the Gulf of Tadjoura, Djubouti, and in Western Yemen.





In the Atlantic Ocean, substantial bleaching was observed by local coral reef managers and monitoring networks in southeastern Florida and the Florida Keys in August and September 2014. Then in September and October 2015, moderate to severe coral bleaching (and disease) and low to moderate mortality were observed along the Florida Reef Tract (including in the National Marine Sanctuary) for the second year in a row. In mid-July 2016, a Bleaching Warning was issued for both the Florida Keys and Southeast Florida 5km Regional Virtual Stations. However, significant bleaching heat stress (Bleaching Alert Levels 1 and 2) did not develop in Florida in 2016, providing much needed relief to corals and other reef organisms that were still recovering from severe back-to-back bleaching. Additionally, although Alert Level 1 heat stress was predicted for the Florida Keys and Southeast Florida 5km Regional Virtual Stations througout most of July and into early August, it did not materialize. Only low-level bleaching heat stress developed, and it dissipated as of mid-September 2017.

In the Gulf of Mexico, heat stress in the Flower Garden Banks, Texas and Yucatan Peninsula dissipated in early November 2016. Alert Level 1 heat stress was predicted at all three 5km Regional Virtual Stations for the Gulf region through early August; however it only materialized in the Yucatan Peninsula. In mid-September, the high heat stress increased further, elevating to Alert Level 2 bleaching conditions. As of early October 2017, severe Alert Level 2 heat stress remains but is expected to diminish in the next few weeks.

A strong bleaching season in 2015 impacted coral reefs throughout the Caribbean. Bleaching of Caribbean corals at a number of reef locations (e.g., Cuba, the Turks and Caicos, the Bahamas, Haiti, the Dominican Republic, and Mexico) in 2015, as reported by partner organizations with divers working on affected reefs, including the XL Catlin Seaview Survey and Reef Check, led to NOAA's declaration of the Third Global Coral Bleaching Event on record (after the 1998 and 2010 global events). In early November 2016, high levels of bleaching heat stress returned to the eastern and southern portions of the Caribbean basin. Bleaching conditions remained until late December 2016. As of early October 2017, Alert Levels 1 and 2 heat stress are present at more than half of CRW's 5km Regional Virtual Stations in the Caribbean, especially in the southern portion of the basin. High heat stress is expected to remain for the next 5-8 weeks and expand to the northern Caribbean. We recommend coral reef managers and other stakeholders continue to closely monitor CRW's daily 5km satellite coral bleaching heat stress monitoring products and Four-Month Coral Bleaching Heat Stress Outlook for the Caribbean region for the most up-to-date near-real-time monitoring and predictions of environmental conditions on their coral reefs.




Click here to access the most recent Pacific Climate Update from NOAA CRW.




For more information about the Top 10 Things Resource Managers and Other Coral Reef Stakeholders Can Do Before, During, and After a Bleaching Event, please visit: http://www.coris.noaa.gov/activities/projects/bleach_events/.





Click here to access a presentation, given by the NOAA CRW Coordinator on March 17, 2017, as part of the Virginia Institute of Marine Science Spring Seminar Series, on the Third Global Coral Bleaching Event.





Official Bleaching Announcements and Select Media Stories

2017 June 29 About the Reef: Reef Health (Link to the source article)
2017 June 19 Global Coral Bleaching Event Likely Ending
2017 April 10 Scientists Just Confirmed the Great Barrier Reef Bleached (Link to the source article)
2017 April 8 Australia Floats Plan To Keep Corals Cool In A Warming World (Link to the source article)
2017 March 16 Great Barrier Reef's future looks grim (Link to the source article)
2017 March 16 'Are we there yet?': Fears that 'significant' coral mortality still to come (Link to the source article)
2017 March 15 Large Sections of Australia’s Great Reef Are Now Dead, Scientists Find (Link to the source article)
2017 March 13 Scientists race to prevent wipeout of world's coral reefs (Link to the source article)
2017 March 10 Great Barrier Reef bleached for unprecedented second year running (Link to the source article)
2017 March 10 Warm ocean temperatures cause another bleaching event on Great Barrier Reef (Link to the source article)
2017 March 10 Second wave of mass bleaching unfolding on Great Barrier Reef (Link to the source article)
2017 February 17 Variable levels of bleaching reported in Great Barrier Reef Marine Park (Link to the source article)
2016 November 12 In graveyard of dead coral in Pacific hope and life bloom (Link to the source article)
2016 November 12 In Singapore: Coral bleaching getting worse (Link to the source article)
2016 November 10 Majority of Sekisei shoko coral reef dies with 97% extremely severely bleached (Link to the source article)
2016 November 5 Scientists: Flower Garden Banks coral bleaching part of global problem (Link to photos)
2016 September 9 Summary of Findings for 2015 Coral Bleaching Surveys: South Kohala, North Kona
2016 September 9 Hawaii Division of Aquatic Resources Coral Bleaching Recovery Plan (Link to the source article)
2016 June 20 U.S. coral reefs facing warming waters, increased bleaching
2016 June 8 As coral bleaching goes global, scientists fear worst is yet to come (Link to the source article)
2016 June 8 World oceans day: healthy oceans - healthy planet (Link to the source article)
2016 June 7 Maldives warns coral bleaching could prompt reef closure
2016 June 2 Updated Map of observed coral mortality for the Great Barrier Reef
2016 June 2 Updated Map of observed bleaching for the Great Barrier Reef
2016 June 2 Coral bleaching update on the Great Barrier Reef (Link to the source article)
2016 June 1 El Niño Warming Turns Coral Garden in Marine National Monument to Graveyard
2016 May 30 Coral death toll climbs on Great Barrier Reef (Link to the source article)
2016 May 27 Update on coral bleaching and mortality in the Great Barrier Reef (Link to the source article)
2016 May 26 Thailand closes dive sites over coral bleaching crisis (Link to the source article)
2016 May 13 Update on coral bleaching in the Great Barrier Reef (Link to the source article)
2016 May 13 Updated Map of observed bleaching for the Great Barrier Reef (Link to the source article)
2016 May 6 Update on coral bleaching in the Great Barrier Reef (Link to the source article)
2016 April 20 Press release: Only 7% of Great Barrier Reef has avoided coral bleaching (Link to the source article)
2016 April 20 Map of reef survey results accompanying Great Barrier Reef press release (Link to the source article)
2016 April 20 Statement on Great Barrier Reef coral bleaching surveys (Link to the source article)
2016 April 12 Dead Kiribati reefs mark potential arrival at "dangerous" climate change threshold (Link to the source article)
2016 April 12 Updated Map of observed bleaching for the Great Barrier Reef (Link to the source article)
2016 April 12 Update on coral bleaching in the far northern Great Barrier Reef (Link to the source article)
2016 April 11 ABC-TV News interview with Mark Eakin about Great Barrier Reef bleaching (Link to the source video)
2016 April 9 Climate-Related Coral Bleaching and Death - A Global Update (Link to the source article)
2016 April 6 Intense bleaching thermal stress continues devastating reefs of Kiribati (Link to the source article)
2016 April 5 National Coral Bleaching Taskforce unleashes an armada of experts (Link to the source article)
2016 April 1 Map of observed bleaching for the Great Barrier Reef (Link to the source article)
2016 April 1 Update on coral bleaching in the far northern Great Barrier Reef (Link to the source article)
2016 April 1 El Niño continues devastating reefs worldwide, including the Great Barrier Reef (Link to the source article)
2016 March 29 Appeal for underwater photographers and videographers to document bleaching (Link to the source video)
2016 March 29 Coral Bleaching Taskforce documents most severe bleaching on record (Link to the source article)
2016 March 21 Scientist witnesses severe coral bleaching at Lizard Island (Link to the source article)
2016 March 20 Coral mortality rises in remote far northern Great Barrier Reef (Link to the source article)
2016 March 14 Australian National Coral Taskforce puts plan into effect as bleaching intensifies (Link to the source article)
2016 March 14 Coral Bleaching Intensifies in the Far Northern Great Barrier Reef (Link to the source article)
2016 March 8 Marine Reserve in Reunion Alerts of Coral Bleaching (Link to the source article)
2016 March 1 Widespread Low Level Coral Bleaching on the Great Barrier Reef (Link to the source article)
2016 February 25 New Caledonia Mass Bleaching (Link to the source article)
2016 February 23 El Niño Prolongs Longest Global Coral Bleaching Event  
2015 October 8 NOAA Declares Third Ever Global Coral Bleaching Event  
2015 September 11 Record Ocean Temperatures Causing Coral Bleaching Across Hawaii  
2015 July 6 Coral Bleaching Threat Increasing in Western Atlantic and Pacific Oceans  



Progression of the Third Global Coral Bleaching Event (2014-June 2017)


The following content was drafted from the Eakin et al. article, "Ding, Dong, The Witch is Dead (?) - Three Years of Global Coral Bleaching 2014-2017", published in Reef Encounter in August 2017:

In 2016, we wrote in Reef Encounter about the ongoing Third Global Coral Bleaching Event, which was forecast to continue into 2017 (Eakin et al. 2016). As predicted, the 2015-16 strong El Niño formed, worsening the bleaching, and was followed by a La Niña event. Despite the end of the La Niña, high temperatures persisted into 2017. At least half of the world's coral reef areas bleached in two or all three years of the event, and many suffered the worst bleaching ever documented. As of June 2017, the three-year-long, Third Global Coral Bleaching Event has most likely ended (National Oceanic and Atmospheric Administration (NOAA) 2017) but remains the longest, most widespread, and probably the most destructive ever recorded.

Recap: Bleaching in 2014

In June 2014 coral bleaching began in Guam and the Commonwealth of the Northern Mariana Islands (CNMI, Heron et al. 2016), and it looked like an El Niño was predicted to form but never did. Papaha̅naumokua̅kea Marine National Monument, the Main Hawaiian Islands (DAR 2014, Bahr et al. 2015), southeastern Florida and the Florida Keys (FRRP 2015a) saw bleaching in August and September, while the Republic of the Marshall Islands (Fellenius 2014, Eakin et al. 2016) saw bleaching from September-November.

Recap: Bleaching in 2015

Bleaching worsened as heat stress moved into the southern hemisphere in late 2014/early 2015, striking in the South Pacific, large areas of the Indian Ocean, and parts of Southeast Asia - including severe localized bleaching in Dongsha Atoll in June 2015 (DeCarlo et al. 2017). With the onset of the 2015-16 El Niño, the heat stress focused on the central and eastern Tropical Pacific. The heat stress spread northward, causing the worst bleaching on record in the Main Hawaiian Islands in October 2015 (TNC 2015, Eakin et al. 2016, Kramer et al. 2016, Rodgers et al. 2017, Rosinski et al. 2017). In the Atlantic, September-October brought moderate to severe coral bleaching (and disease) and low to moderate mortality to Florida's coral reefs for the second year in a row (FRRP 2015b, FRRP 2016a); bleaching at varying severities and scales was then reported from multiple locations across the eastern and western Caribbean through October. As of October 2015, with widespread bleaching in each of the Indian, Pacific, and Atlantic basins, NOAA declared that the Third Global Coral Bleaching Event was underway. By the end of 2015, 41% of global coral reefs had been exposed to heat stress of 4°C-weeks or more (measured by NOAA Coral Reef Watch's Daily Global 5km Degree Heating Week version 3 - DHW) and almost all of the world's reefs had exceeded their normal warm-season temperatures.

   
Figure 1. NOAA Coral Reef Watch Maximum Bleaching Alert Area map for January-December 2016. Severe coral bleaching was reported in all areas circled in white on map and listed below the map. Data from Coral Reef Watch Daily Global 5km Coral Bleaching Heat Stress Monitoring Product Suite version 3 (Liu et al. 2017).
 



Bleaching in 2016

As the El Niño continued to strengthen, heat stress and bleaching returned to the Southern Hemisphere. Heat stress in 2016 was much more widespread than in 2015, encompassing 51% of global coral reefs (measured by Coral Reef Watch's DHW product). Even more important was the severity. The El Niño resulted in continuous heat stress in the Central Pacific from April 2015 to May 2016. The Northern Line Islands heat stress values were the highest Coral Reef Watch has ever documented (DHW > 25°C-weeks) and caused the worst bleaching-related mortality ever reported. By May 2016, this included 80% of total coral cover dead and an additional 15% bleached in Kiritimati (Harvey 2016), as well as 98% total coral cover dead at Jarvis Island with substantial reduction to reef structural complexity (investigation into the mechanism of this rapid erosion is underway). Severe heat stress in Fiji's lagoons caused sudden and widespread coral death in February just weeks before Cyclone Winston cooled ocean temperatures. Bleaching in New Caledonia in March caused wide swaths of lagoon corals, especially Acropora, to fluoresce in multi-colored pastels. The first major bleaching ever documented on the Northern and Far Northern sectors of the Great Barrier Reef (GBR) peaked in March (Hughes et al. 2017). This was the worst bleaching ever seen in the GBR resulting in 29% mortality of shallow-water corals across the entire reef (GBRMPA 2017). Coral bleaching started in the Western Indian Ocean in January and peaked by May (CORDIO-EA), with bleaching in the Seychelles ranging from 69-99% resulting in a subsequent 50% reduction in hard coral cover (SIF 2017). Bleaching in Southeast Asia caused Thailand to close many of its coral reefs to recreational diving activities in May (AFP 2016). Bleaching in Guam, especially Tumon Bay, returned for the fourth year in a row.

In the boreal summer, bleaching returned to the Northern Hemisphere, with extensive (over 90%) bleaching observed in the largest coral reef in the Ryukyu Islands, Japan starting in July, resulting in 70% mortality (Harvey 2017). The heat stress then brought bleaching back to the western Atlantic, Gulf of Mexico, and Caribbean from September through November, with the western Caribbean hit hardest. Florida suffered only mild to moderate bleaching in summer 2016 but was struck by another round of coral disease, including the loss of 95% of pillar coral (Dendrogyra cylindrus) across the state (FRRP 2016b). October brought the worst bleaching ever to the Flower Garden Banks, while patchy bleaching was reported from the eastern Caribbean. Moderate to severe bleaching (generally more severe than in 2015) also was reported in parts of the Mesoamerican Barrier Reef in October and November, with deeper reefs being impacted moreso than shallow. The year culminated in a return of bleaching to the Republic of the Marshall Islands by November 2016. Figure 1 (above) shows the total extent of heat stress in 2016 and regions with confirmed coral bleaching reports.

   
Figure 2. NOAA Coral Reef Watch Maximum Bleaching Alert Area map for January-May 2017, with coral reef areas with reports of bleaching circled in white. Data from Coral Reef Watch Daily Global 5km Coral Bleaching Heat Stress Monitoring Product Suite version 3 (Liu et al. 2017).
 


Bleaching in the First Half of 2017

Mild coral bleaching started in Fiji in January 2017, but stormy conditions cooled the water, averting severe thermal stress and bleaching. However, severe bleaching was reported in Niue in February and by March, bleaching returned to American Samoa and Samoa. This time, bleaching was much more extensive on the outer reefs than in 2015. The first-ever consecutive bleaching was confirmed on the GBR in March (Hughes and Kerry 2017). This time, the Northern (again) and Central sectors were most impacted in what would have been the worst bleaching of the GBR, if not for the mortality from 2016. Heat stress was limited in the Indian Ocean, with the only pocket of moderate bleaching reported from southwestern Madagascar in April (CORDIO-EA). Reports indicate that bleaching elsewhere in the Indian Ocean has been mild. Figure 2 shows the total extent of heat stress in 2017 and regions with confirmed bleaching reports.

As of September 2017, NOAA's El Niño-Southern Oscillation Alert System has issued a La Niña Watch, with a 55-60% chance of La Niña formation during late 2017. NOAA Coral Reef Watch's Four-Month Coral Bleaching Heat Stress Outlook indicates that bleaching is much less likely in most of the Northern Hemisphere this summer (Figure 3). However, the Outlook through December 2017 does indicate a potential for significant bleaching and coral mortality in the western Pacific Ocean (from Guam through Micronesia); in the eastern portion of the Papaha̅naumokua̅kea Marine National Monument; and in the Caribbean Sea.

While more coral bleaching may still occur in 2017, the absence of widespread coral bleaching in the Indian Ocean appears to signal that the three-year-long global event has ended.

   
Figure 3. Map of areas where 60% or more of the model ensemble members were predicting heat stress at each of NOAA Coral Reef Watch's bleaching heat stress alert levels through December 2017 (as of September 12, 2017). Data from Coral Reef Watch Four-Month Coral Bleaching Heat Stress Outlook version 4 (Liu et al. 2017).
 

Documenting the 2014-2017 Global Bleaching Event

With the Third Global Coral Bleaching Event apparently coming to a close, NOAA Coral Reef Watch is now working in earnest to collate reports on the global extent of this event. We are planning a follow-on global summary paper similar to our 2005 Caribbean Bleaching Event paper (Eakin et al. 2010). We truly appreciate all reports we have received so far, many of which contributed to this brief review of the global event. Please assist us further by continuing to report coral bleaching and disease observations to your existing regional programs, such as the Global Coral Reef Monitoring Network nodes, ReefCheck, CORDIO-EA, AGRRA, etc. Also, please send a brief email to coralreefwatch@noaa.gov to let us know where you submitted them. If you aren't involved in one of these monitoring programs, please submit your reports directly to the Coral Reef Watch Report Bleaching web page. Coral Reef Watch needs both bleaching and non-bleaching observations to document the spatial extent and timing of the event and to continue to improve its satellite and climate model-based products. Contributing your observations ensures that your site's data are considered in global analyses; gives context to how bleaching patterns at your sites compare with global patterns; and provides access to the latest global coral bleaching data analyses to communicate climate impacts to decision makers. All contributors will have the opportunity to co-author peer-reviewed publication(s) on global and/or regional bleaching.

A special issue or portion of an issue of the International Society for Reef Studies journal Coral Reefs will focus on this event. This will be an opportunity for you to publish more detailed studies on coral health, bleaching, disease, and mortality in your country or region associated with the Third Global Coral Bleaching Event.

Since our last update (Eakin et al. 2016), filmmakers at Exposure Labs completed a 90-minute documentary on their efforts to capture time-lapse imagery of coral bleaching during the Third Global Coral Bleaching Event. The film includes many of your contributions to their global call for bleaching reports and part was shot at the 13th International Coral Reef Symposium in Honolulu, Hawaii. The resulting film, Chasing Coral, just premiered on Netflix on July 14, 2017 (see two more detailed articles about the film in the August 2017 edition of Reef Encounter).

Final Thoughts

With the end of the Third Global Coral Bleaching Event, it is more essential than ever that coral reef ecosystem scientists, managers, and other stakeholders, including the public, work together to increase our collective knowledge as we continue toward a future with a changed climate. While continuing and expanding efforts to reduce local stressors, we all must work to address the main cause of global warming through reducing atmospheric carbon dioxide concentrations and emissions.





Acknowledgements

NOAA Coral Reef Watch work is supported primarily by the NOAA Coral Reef Conservation Program and the NOAA National Environmental Satellite, Data, and Information Service's Center for Satellite Applications and Research.



References

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Heron, S.F., Johnston L., Liu G., Geiger E.F., Maynard J.A., De La Cour J.L., Johnson S., Okano R., Benavente D., Burgess T.F.R., Iguel J., Perez D., Skirving W.J., Strong A.E., Tirak K., Eakin C.M. (2016a) Validation of Reef-scale Thermal Stress Satellite Products for Coral Bleaching Monitoring. Remote Sens. 8(1): 59, doi:10.3390/rs8010059.

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For more information, please contact coralreefwatch@noaa.gov


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