NOAA Coral Reef Watch Current Global Bleaching: Status Update & Data Submission

On April 15, 2024, NOAA (in partnership with the International Coral Reef Initiative) confirmed the world is in the midst of its 4th global coral bleaching event. From 1 January 2023 to 20 May 2025, bleaching-level heat stress has impacted 83.8% of the world’s coral reef area and mass coral bleaching has been documented in at least 83 countries and territories.

The ongoing global coral bleaching event is the biggest to date. The previous record was during the 3rd global coral bleaching event, which occurred from 2014-2017, when 68.2% of the world's reef area experienced bleaching-level heat stress. The 1st and 2nd global coral bleaching events occurred in 1998 and 2010, respectively.

NOAA CRW's 5km Bleaching Alert Area Maximum product, for the period January 1, 2023 - May 20, 2025. 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.

An animation of NOAA CRW's Daily 5km Bleaching Alert Area Maximum product, for the period January 1, 2023 - May 20, 2025.

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!

Other Coral Bleaching Heat Stress Updates, Reports & Analyses (Regional and Global)

Reporting Coral Bleaching Data and Observations

**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 Bleaching Observations Data Entry Template
(Excel spreadsheet, 35KB, Revised April, 2025)

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.