Reefs at Risk Revisited is a high-resolution update of the original global analysis, Reefs at Risk: A Map-Based Indicator of Threats to the World’s Coral Reefs. Reefs at Risk Revisited uses a global map of coral reefs at 500-m resolution, which is 64 times more detailed than the 4-km resolution map used in the 1998 analysis, and benefits from improvements in many global data sets used to evaluate threats to reefs (most threat data are at 1 km resolution, which is 16 times more detailed than those used in the 1998 analysis).
"Comparison of the average hard coral cover between the three five-year periods comprising the last 15 years (2005-09, 2010-14, 2015-19, Tab. 9.3) indicated that there was a high degree of confidence (93%) in the long-term decline, despite the uncertainty in individual yearly estimates. Further, the vast majority (90%) of this decline occurred between 2010-14 and 2015-19, suggesting that the rate of decline in hard coral cover has accelerated during the last five years"