(Version 3.1.2, released September 15, 2021)
Number of Significant Bleaching-level Heat Stress Events (DHW≥4)
Number of Severe Bleaching-level Heat Stress Events (DHW≥8)
Time between Heat Stress Events (DHW>0)
Time between Significant Bleaching-level Heat Stress Events (DHW≥4)
Time between Severe Bleaching-level Heat Stress Events (DHW≥8)
Home | Stress Frequency | Stress Onset | SST Variability | SST Trend | Climatology | Annual History
Stress Frequency (261Mb) | Stress Onset (421Mb) | SST Variability (261Mb) | SST Trend (141Mb)
Climatology (621Mb) | Annual History (7.3Gb)
Stress Frequency metrics: Coral reef sites that have experienced fewer heat stress events may have natural protection from exposure to conditions conducive to coral bleaching (e.g., strong mixing, upwelling). However, corals at those sites may have an enhanced sensitivity to heat stress, resulting in higher impacts during a stress event. Alternatively, sites that have been regularly exposed to heat stress can have a reduced sensitivity - and therefore lower impact from the stress. Stress events are defined for 1985-2020 by applying Coral Reef Watch's Degree Heating Week (DHW) methodology at coral reef-containing and adjacent satellite pixel locations worldwide, using the Version 3.1 daily global 5km CoralTemp satellite sea surface temperature (SST) data product. The three thresholds for heat stress displayed here correspond to occurrence (DHW>0); significant coral bleaching (DHW≥4); and severe, widespread bleaching and significant coral mortality (DHW≥8).
The range of values calculated from analyzed pixels is shown in [brackets] after each metric name.
Number of [0-53 events] and Period between [0.3-34.0 years] Heat Stress Events: These metrics present how many heat stress events (at the DHW thresholds of DHW>0, DHW≥4, and DHW≥8) have occurred in recent history, and the average time period between them, respectively. Calculation of the average time period between events requires at least two events (i.e., one period between) during 1985-2020. The color scale is consistent for the number of heat stress events to allow comparison between threshold levels. A separate (but consistent) color scale is used for the time between events ("n/a" represents locations with less than two events and, therefore, no period between).