Exploring Threats to Coral Reefs with GIS Data Sets
by
Katie Reytar and - 
This piece originally appeared in the Winter 2012 edition of Esri's ArcUser Magazine. The full text, graphics, and GIS datasets are available here.
Assessing Threats, Raising Awareness
WRI has been using GIS to develop highly detailed maps of the threats to coral reefs worldwide since 1998. Coral reefs are vital to maintaining the diversity and viability of marine ecosystems. They provide livelihoods and food for coastal communities and shelter and protection for shorelines.
The goal of the Reefs at Risk project is to produce globally consistent data, maps, and reports that are hybrids of model results and observational evidence that can be used to raise awareness about the location and severity of specific threats to coral reefs. GIS is used to develop spatial indicators linking human activities and livelihoods to pressures on coral reef ecosystems.
Reefs at Risk in the Present, 2030, and 2050: The top map (A) shows reefs classified by present integrated threats from local activities. In the middle (B) and bottom (C) maps, reefs are classified by integrated local threats and projections of thermal stress and ocean acidification for 2030 and 2050
The project has spawned four publications between 1998 and 2011—a global analysis; two detailed regional analyses; and, most recently, a high-resolution update of the first global analysis.
Reefs at Risk Revisited improves on the 1998 global analysis in several important ways. It uses a global map of coral reefs at 500-meter resolution and benefits from improvements in the many global datasets used to evaluate threats to reefs. Most threat data is at 1-square-kilometer resolution. For the first time, it also includes an assessment of climate-related threats to reefs as well as an assessment of the vulnerability of nations and territories to coral reef degradation, based on their dependence on coral reefs and their capacity to adapt. Finally, it takes advantage of the many advances in online web mapping applications, such as ArcGIS Explorer Online, to reach a broader audience that is web savvy, but not necessarily GIS savvy.