Unless carbon dioxide emissions are reduced by the end of this century, all World Heritage sites containing reefs will experience severe bleaching, and will cease to contain functioning coral reef systems, according to a UNESCO report. The report finds that unless CO2 emissions are reduced by the end of the century, all reef-containing World Heritage sites will experience annual severe bleaching, and will cease to host functioning coral reef ecosystems. The report, UNESCO's first assessment of the impacts of climate change on World Heritage coral reefs, indicates that heat stress, sufficient to cause severe coral bleaching and mortality, cannot be managed at the local level, and say that national and global action are required to limit warming to 1.5°C. To find out more go to Assessment: World Heritage coral reefs likely to disappear by 2100 unless CO2 emissions drastically reduce.