"Rising Temperatures Trigger New Coral Reef Alert Levels"

The US government's Coral Reef Watch program has added three new alert levels to its heat stress category system due to unprecedented stress on coral reefs, with more than 20 Degree Heating Weeks (DHWs) now constituting a "worst case scenario" at Bleaching Alert Level 5, indicating a risk of mortality in over 80% of corals. This marks the first changes to the system since its introduction in 2009 and reflects the pervasive impacts of global heating on oceans, prompting a need for rethinking response plans and appropriate actions in the face of extreme heat stress.