Coral Bleaching Risk Calculator
Assess coral bleaching risk using Degree Heating Weeks (DHW) based on sea surface temperature anomalies and duration above threshold.
Inputs
Results
Degree Heating Weeks
7.2 °C-weeks
Risk Assessment
Bleaching Warning
How to Use This Calculator
- Enter Weekly SST Anomaly, Weeks Above Threshold, and MMM Threshold Temperature.
- Review Degree Heating Weeks (°C-weeks) and Risk Assessment.
- Use NOAA Alert Level and Est. Bleaching Percentage (%) to inform your decision.
How the result changes with Weekly SST Anomaly
| Weekly SST Anomaly | Degree Heating Weeks | Risk Assessment |
|---|---|---|
| 0.5 | 3 °C-weeks | Bleaching Watch |
| 1.75 | 10.5 °C-weeks | Alert Level 1 — Bleaching Likely |
| 3.25 | 19.5 °C-weeks | Alert Level 2 — Severe Bleaching Likely |
| 4.5 | 27 °C-weeks | Alert Level 2 — Severe Bleaching Likely |
What each input means
- Weekly SST Anomaly
- Sea surface temperature anomaly above the maximum monthly mean (MMM) climatology in °C.
- Weeks Above Threshold
- Number of consecutive weeks the SST has remained above the bleaching threshold (1°C above MMM).
- MMM Threshold Temperature
- Maximum Monthly Mean (MMM) sea surface temperature for the region. Bleaching risk begins 1°C above this value.
How this is calculated
Worked example, using the default values
- Identify Input ParametersWeekly SST Anomaly = 1.2, Weeks Above Threshold = 6, MMM Threshold Temperature = 28.5 = 3 input(s) provided
- Calculate Degree Heating WeeksDegree Heating Weeks7.2 = 7.2
- Calculate Risk AssessmentRisk AssessmentBleaching Warning = Bleaching Warning
- Calculate NOAA Alert LevelNOAA Alert Level2 = 2
- Calculate Est. Bleaching PercentageEst. Bleaching Percentage16 = 16
Related Calculators
The questions that sit next to this one — chosen by subject, including calculators filed under a different category.
Sea Level Rise Impact Calculator
Estimate coastal inundation area and shoreline retreat from sea level rise based on coastline length, slope, and rise amount.
OceanographySeawater Density Calculator
Calculate seawater density from temperature, salinity, and pressure using a simplified UNESCO equation of state.
Marine BiologyCoral Growth Rate Calculator
Model coral colony linear extension rate based on species growth baseline, water temperature, light (PAR), and aragonite saturation state.
ConservationCoral Reef Restoration Cost Calculator
Estimate per-hectare costs for coral reef restoration using gardening, larval seeding, or substrate deployment methods.
OceanographyBathymetric Profile Calculator
Calculate average depth, seafloor slope, and gradient from start/end depths and horizontal distance.
More in Science & Physics.