While there are multiple threats affecting Guam's coral reefs, sedimentation, overfishing, and crown of thorns outbreaks are probably the most serious threats to Guam's reefs. Most of the threats currently affecting Guam's reefs are local in origin, a result of the activities we do here on the island (or in the surrounding waters). But scientists around the world are warning of the threats to reefs posed by global climate change. These threats, including coral bleaching, ocean acidification, and sea level rise, are expected to challenge even the most healthy reefs and could result in the loss of much of the world's coral reefs - including Guam's.