As of May 12, 2016, NOAA's National Centers for Environmental Prediction has issued an El Niño Advisory/La Niña Watch. Sea surface temperature (SST) anomalies continued decreasing across most of the equatorial Pacific this month. A transition to a brief period of ENSO-neutral conditions is likely during early Northern Hemisphere summer, with an increasing chance (about 75%) of La Niña conditions developing in summer and persisting through fall and winter 2016-17, as seen in the figure on the left.
NOAA Coral Reef Watch's most recent Coral Bleaching Alert Area is below. This figure shows the regions currently experiencing high levels of thermal stress that cause coral bleaching.
NOAA Coral Reef Watch's most recent Four-Month Coral Bleaching Thermal Stress Outlook is below. This figure shows the distribution of the lowest thermal stress levels predicted by at least 60% of the model ensemble members. In other words, there is a 60% chance that the displayed thermal stress levels will occur.daily 5-km satellite coral bleaching thermal stress monitoring products and Four-Month Coral Bleaching Outlook indicate that the coral bleaching thermal stress in the eastern Pacific Ocean remains high. The Costa Rica Pacific 5-km Regional Virtual Station remains at Alert Level 2 and the Panama Pacific West station remains at Alert Level 1, although heat stress in these areas is expected to dissipate shortly. Thermal stress surrounding the Clipperton Island (France) station continues to increase, and Alert Level 1 bleaching is expected in the next few weeks. El Salvador is also expected to reach Alert Level 1 bleaching conditions in late May-early June.
In the central equatorial Pacific Ocean, reefs in the Northern Line Islands (Kiribati), Southern Line Islands, and the Marquesas Islands are again at Alert Level 2 bleaching conditions associated with significant bleaching and widespread mortality. The Northern Cook Islands also just reached Alert Level 1. The Phoenix Islands (Kiribati) remain at Alert Level 2, with no end in sight. As noted in multiple articles above and by numerous news outlets worldwide, in Kiribati, persistent elevated ocean temperatures (as high as 31.4-degrees Celsius) since June 2015 have killed most of the corals in the region. Photos taken by scientists surveying the reef damage, especially around the island of Kiritimati, where more than 80% coral mortality has been documented, are gruesome. The ongoing high bleaching thermal stress in Kiribati is tied to the very strong El Niño that has only begun to dissipate, but whose effects will last for many months in the southern hemisphere. It is estimated that only 5% of Kiribati's reefs will survive this bleaching thermal stress event.
It also is important to note that waters in Southeast Asia and the Coral Triangle continue to heat up. Many different CRW 5-km Regional Virtual Stations are monitoring Bleaching Warning stress presently, especially to the east of Sumatra, throughout the Java Sea (south of Malaysia), and into southern and western Indonesia, including the Banda and Molucca Seas. One Regional Virtual Station, West Nusa Tenggara, has been at Alert Level 1 since late February. The bleaching thermal stress in much of the Southeast Asia and Coral Triangle region is expected to elevate quickly to Alert Level 1 and 2 conditions in the weeks ahead. We will continue to monitor the developing stress in these regions and provide updates.
While bleaching thermal stress has now left Australia's Great Barrier Reef (GBR), as reported in multiple articles above and by news sources around the world, high ocean temperatures these last few months did significant damage to the GBR. Australia's National Coral Bleaching Task Force (of which NOAA CRW is a partner) reported that of the 911 coral reefs it surveyed by air along the full 2,300 km of the Great Barrier Reef (GBR), 93% of the reefs exhibited signs of bleaching. Of those reefs that bleached, 316 - nearly all of which are in the remote, usually protected northern GBR - displayed severe bleaching (i.e., 60-100% of corals were bleached on the reef). Divers surveying the northern GBR have also documented 50% coral mortality. The Great Barrier Reef Marine Park Authority now considers this to be the worst bleaching event in the history of the GBR.
Along the western coast of Australia, Scott to Ashmore Reefs is expected to remain at Alert Level 2 conditions for much of May, before the thermal stress dissipates completely. The other 5-km Regional Virtual Stations in the area range from No Stress to Bleaching Watch only.
Thermal stress also continues to develop across much of the Indian Ocean.
Australia's Pulu Keeling
remains under Alert Level 2, associated with significant bleaching and widespread mortality.
Northern Mauritius, which has been at Alert Level 2 for weeks now,
is expected to maintain this high level of bleaching thermal stress for an additional few weeks, while
Kenya continue at Alert Level 1.
Many other 5-km Regional Virtual Stations in the Western Indian Ocean are also
experiencing stress at Bleaching Watch and Bleaching Warning levels. Historical patterns from past El Niño and
CRW's Four-Month Coral Bleaching Outlook both indicate thermal stress should intensify across the Indian Ocean over the next two
months, then follow with thermal stress in the Coral Triangle and Southeast Asia by mid-2016. Bleaching has already been
reported from western India and Aldabra Atoll.
The Main Hawaiian Islands (MHI), which observed record levels of bleaching in 2014 and static Alert Level 2 conditions (associated with significant, widespread coral bleaching and mortality) in October and November 2015, remain at a level of No Stress now. The Northwestern Hawaiian Islands (NWHI), which sustained high, prolonged levels of bleaching thermal stress in 2014 and some subsequent coral death, also remain under No Stress conditions. CRW continues to collect data from field partners, including Hawaii's Eyes of the Reef (EOR) volunteer community reef monitoring program concerning the extent and severity of the bleaching and coral death observed in the MHI and NWHI in 2015.
In the Atlantic Ocean, substantial bleaching was observed by local coral reef managers and monitoring networks in the Florida Keys in 2014; bleaching and coral disease were again documented in August and September 2015 in the Florida Keys (including the National Marine Sanctuary) and Southeast Florida. Waters in the region finally cooled in late November, placing the Florida Keys and Southeast Florida Virtual Stations under a level of No Stress.
The 2015 bleaching season ended in the Caribbean as well, with almost all Caribbean 5-km Regional Virtual Stations displaying a level of No Stress. Only the Panama Atlantic West Regional Virtual Station remains under a Bleaching Watch, which is predicted to downgrade to a level of No Stress in 1-2 weeks time.
Of note, the bleaching of Caribbean corals at a number of 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 ever global coral bleaching event on record (after the 1998 and 2010 global events). As of the end of 2015, the global event was expected to have impacted approximately 38% of the world's coral reefs and killed over 12,000 square kilometers of reefs. This has put at risk the lives and livelihoods of millions of people, who rely on coral reefs for sustenance, income, and coastal protection. U.S. coral reefs, in particular, were hit quite hard by this event; predictions indicate that as of the end of 2015, almost 95% of U.S. coral reefs were exposed to the prolonged high temperatures that cause coral bleaching.
Click here to read the NOAA press release of October 8, 2015 announcing the third ever documented global coral bleaching event!
As noted in the NOAA press release, a large concern remains as to impacts of the strong El Niño, which climate models indicate will cause coral bleaching again in the Indian and southeastern Pacific Oceans in the next few months. This may cause bleaching to spread globally again in 2016, as can be seen in CRW's extended bleaching outlooks for the period May-August 2016.
Please continue to visit the CRW website for more information on the developing coral bleaching conditions globally and to view the current Four-Month Coral Bleaching Outlook.
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,
With the current (2015) El Niño continuing to develop and intensify in the Northern Hemisphere, the following is a brief overview of the pattern and timing of thermal stress that resulted in widespread severe coral bleaching during 1997-1999. Past reports have estimated that over 15% of the world's coral reefs were effectively lost during the 1997-1999 period (Wilkinson 2000). At that time, NOAA Coral Reef Watch observed widespread, prolonged high temperatures that caused coral bleaching. This was associated with what has been argued to be the largest El Niño on record (1997-1998) followed immediately by a strong La Niña (1998-1999). In general, many areas that are untouched by warming during an El Niño are influenced by warming during a La Niña (see Eakin et al. 2009).
The following discussion uses the NOAA Coral Reef Watch SST Anomaly and Bleaching Alert Area products to illustrate the events. The Bleaching Alert Area shows patterns of areas with accumulated thermal stress sufficient to cause coral bleaching. The patterns are a bit different, and more coral-focused, than those visible in the SST Anomaly data. More on these products can be found at: http://coralreefwatch.noaa.gov/satellite/index.php.
The classical El Niño warming pattern formed by May 1997, with initiation of SST warming from the central tropical Pacific eastward to the South American coastline. Prolonged thermal stress with the potential to cause bleaching was seen along the equator, from Howland and Baker Islands east to the Galapagos and the Ecuadorian coastline, during the remainder of 1997. During this time, warming also proceeded northward along the South American coast to Panama. Additionally, warming was seen reaching northeast to Mexico, and some warming was seen along the Central American Coastline. Limited warming was seen in the Caribbean.
By early 1998, the classic El Niño pattern was fully developed, with broader areas of high temperature in the eastern Tropical Pacific and extending up the Central American coast past Costa Rica, including all of the eastern Tropical Pacific islands; high temperatures in these regions began to dissipate in June. Bleaching levels of warming were seen along the Great Barrier Reef in February-March. Warming also began in the eastern to central Indian Ocean south of the equator, spreading to the eastern Indian Ocean by March, and dissipating after May.
In May and June, bleaching levels of warming were also seen across the Indian Ocean north of the equator and into Southeast Asia.
Bleaching warming in the Western Atlantic/Gulf of Mexico/Caribbean is most commonly seen in the year after the onset of an El Niño (see figure on left from Eakin et al. 2009).
The bleaching warming started to develop in July 1998 and peaked in the Gulf of Mexico in August and in the Caribbean Sea in October.
By 1999, the worst of the thermal stress was over, from a coral bleaching perspective, but only after major losses of coral reefs worldwide in 1998. Some warming was seen along the Great Barrier Reef in early 1999 but was much weaker than the prior year. Conditions were rather quiescent until August, when warming of the western North Pacific led to low bleaching levels of thermal stress that reached down to the Mariana Islands. Warming was again seen in the Caribbean in August-September 1999 but to a lesser extent than in 1998.
Wilkinson CR (2000) Status of Coral Reefs of the World: 2000. Global Coral Reef Monitoring Network and Australian Institute of Marine Science, Townsville, Australia 363pp.
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