Reefs at Risk Revisited

This technical paper details the modeling methodology used by the World Resources Institute for the 'Reefs at Risk Revisited' analysis. It describes how the project quantified and mapped global threats to coral reefs by integrating over 50 data sources into a geographic information system (GIS) to create indices for local and global pressures, including coastal development, pollution, overfishing, thermal stress, and ocean acidification.

• The analysis categorizes human pressures on coral reefs into 'local' and 'global' threats. Local threats include coastal development, watershed-based pollution, marine-based pollution and damage, and overfishing and destructive fishing. Global threats consist of thermal stress (warming sea temperatures) and ocean acidification (driven by increased CO2).
• The 'Integrated Local Threat Index' combines four local threats by assigning scores of low (0), medium (1), or high (2). The resulting index classifies reefs as Low (0 points), Medium (1–2 points), High (3–4 points), or Very high (5 points or higher).
• Watershed-based pollution was modeled using a simplified version of the Revised Universal Soil Loss Equation (RUSLE) to estimate relative erosion rates across 300,000 watersheds. The model uses slope as the most influential variable, followed by land cover, precipitation, and soil porosity.
• Overfishing threats were evaluated based on coastal population density within 30 km of a reef, adjusted for the available shallow fishing area and proximity to market centers. The model also incorporates data on destructive fishing (blast and poison fishing) and the effectiveness of Marine Protected Areas (MPAs).
• Past thermal stress (1998–2007) was modeled by combining satellite sea surface temperature data from NOAA Coral Reef Watch—specifically identifying areas with a 'Bleaching Alert Level 2' (degree heating weeks ≥ 8)—with severe bleaching observations from ReefBase.
• Future threats for 2030 and 2050 were projected using a 'business-as-usual' scenario for greenhouse gas emissions. Future thermal stress is based on the frequency of reaching the bleaching threshold, while ocean acidification is measured by the projected saturation level of aragonite.

APA

Burke, L., & Reytar, K. (2011). Reefs at Risk Revisited. World Resources Institute. https://wriorg.s3.amazonaws.com/s3fs-public/docs/reefs_at_risk_revisited_technical_notes.pdf

Chicago

Burke, Lauretta, and Katie Reytar. Reefs at Risk Revisited. World Resources Institute, 2011. https://wriorg.s3.amazonaws.com/s3fs-public/docs/reefs_at_risk_revisited_technical_notes.pdf.

Wikipedia

{{cite report |last1=Burke |first1=Lauretta |last2=Reytar |first2=Katie |title=Reefs at Risk Revisited |publisher=World Resources Institute |date=2011 |url=https://wriorg.s3.amazonaws.com/s3fs-public/docs/reefs_at_risk_revisited_technical_notes.pdf |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{burke2011reefs, author = {Burke, Lauretta and Reytar, Katie}, title = {{Reefs at Risk Revisited}}, institution = {World Resources Institute}, year = {2011}, url = {https://wriorg.s3.amazonaws.com/s3fs-public/docs/reefs_at_risk_revisited_technical_notes.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }