Reporting Coral Bleaching Data and Observations to NOAA Coral Reef Watch
(Updated: August 20, 2024)

On April 15, 2024, NOAA (in partnership with the International Coral Reef Initiative) confirmed the world has been experiencing a global coral bleaching event. Bleaching-level heat stress, as remotely monitored and predicted by NOAA Coral Reef Watch (CRW), has been -- and continues to be -- extensive across the Atlantic, Pacific and Indian Ocean basins. Since January 1, 2023, mass coral bleaching has been confirmed on reefs in at least 70 countries and territories around the world.

As of this writing (August 20, 2024), the most extreme accumulated heat stress (Degree Heating Weeks [DHW]≥16°C-weeks; Bleaching Alert Level 4 or higher) is active at reef sites in the west-central equatorial Atlantic Ocean.

This is the fourth global coral bleaching event (or GCBE4) on record -- following the 1998, 2010, and 2014-2017 global events -- and the second in the last 10 years. During the three years of the 2014-2017 global coral bleaching event (GCBE3), more than 65.7% of the world's coral reefs (i.e., satellite pixels containing coral reefs) experienced bleaching-level heat stress. At the time, the GCBE3 was considered the longest, most widespread, and most damaging coral bleaching event on record.

**On May 23, 2024, the GCBE4 surpassed the spatial extent of the GCBE3. As of August 20, 2024, 75.0% of coral reefs worldwide have been impacted by bleaching-level heat stress since January 1, 2023.**
NOAA CRW's 5km Bleaching Alert Area Maximum product, for the period January 1, 2023 - August 11, 2024. This map displays the maximum accumulated heat stress experienced by coral reefs around the world since January 1, 2023. The dark red/brown areas show the accumulated heat stress capable of causing reef-wide bleaching with mortality of heat-sensitive corals. The light brown (Alert Level 3), pink (Alert Level 4), and dark purple (Alert Level 5) areas on the map indicate locations where the magnitude of extreme heat stress exceeds the Bleaching Alert Level 2 threshold, and can lead to multi-species or near complete mortality on a coral reef.


As NOAA and its partners work to document the extent and severity of mass bleaching on coral reefs around the world, the GCBE4 also provides an opportunity for NOAA CRW to compare field data of coral bleaching and mortality with its operational daily global 5km-resolution satellite coral bleaching heat stress data products, to help improve product performance, where possible, for all coral reef ecosystem stakeholders. To do this, we need your help!



**To contribute coral bleaching data and observations (including reports of NO bleaching) to our ongoing effort, please do the following:**

1. E-mail your data files (in Excel, Word, etc.) directly to coralreefwatch@noaa.gov, OR

2. Enter your data into Coral Reef Watch's Google Form, OR

3. Download Coral Reef Watch's quantitative observations questionnaire (below), enter your data, and e-mail the completed questionnaire to coralreefwatch@noaa.gov.


NOAA Coral Reef Watch Quantitative Observations Questionnaire
(Excel spreadsheet, 13kb, Revised Sep 05, 2023)


What Can We All Do?

Predictions pose a daunting future, where even the most conservative estimates suggest mass coral bleaching could occur annually on the majority of coral reefs worldwide by 2050. Increased collaboration among coral reef stakeholders is vital given the critical state of reefs all over the world, and their ecological, economic and societal benefits. In addition to reducing local threats to coral reefs, galvanizing global urgency and action to reduce atmospheric carbon dioxide (i.e., the root cause of rapid anthropogenic climate change) is critical to strengthen conservation and restoration efforts.