Reefs at Risk Revisited

The document details the GIS-based modeling approach used to assess threats to global coral reefs, categorizing them into local pressures (coastal development, watershed-based pollution, marine-based pollution, and overfishing) and global threats (thermal stress and ocean acidification). It explains the proxy indicators, distance-based rules, and data sources used to create an integrated threat index, while acknowledging limitations such as the use of population as a proxy for overfishing and the exclusion of coral disease and storm intensity due to uncertainty.

• The analysis categorizes human pressures on coral reefs into 'local' threats—including coastal development, watershed-based pollution, marine-based pollution and damage, and overfishing and destructive fishing—and 'global' threats, specifically thermal stress and ocean acidification.
• Local threats were modeled using proxy indicators and distance-based rules; for example, coastal development threat is based on the size of cities, ports, and airports, as well as coastal population density, growth, and tourism growth.
• Watershed-based pollution was modeled using a simplified version of the Revised Universal Soil Loss Equation (RUSLE) to estimate relative erosion rates, which serve as a proxy for sediment and pollutant delivery to reefs.
• Overfishing threat is estimated based on coastal population density within 30 km of a reef, adjusted for the available shallow shelf and reef area, and the proximity to market centers.
• The model incorporates the effectiveness of Marine Protected Areas (MPAs) to downgrade overfishing threat levels; reefs within 'effectively managed' MPAs are downgraded to low threat, while those in 'partially effective' MPAs are downgraded by one threat level.
• Global threats are evaluated using external expert data: past thermal stress (1998–2007) combines satellite sea surface temperature and bleaching observations, while future thermal stress and ocean acidification are projected for 2030 and 2050 based on 'business-as-usual' scenarios.
• The analysis produces an integrated local threat index by summing four local threats (scored 0 to 2), which is then combined with past and future climate data to create a final threat classification ranging from low to 'critical'.

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} }