The Great Barrier Reef

The Great Barrier Reef off the coast of Queensland, Australia, is the world's largest coral reef system, composed of over 2,900 individual reefs and 900 islands stretching over 2,300 kilometers. It is so large it can be seen from space and is the world's biggest single structure made by living organisms. The reef is home to extraordinary biodiversity: 1,500 species of fish, 4,000 types of mollusk, 240 species of birds, and 30 species of whales and dolphins. Six of the world's seven species of marine turtle nest there. Climate change is an existential threat to the reef. Rising ocean temperatures cause coral bleaching — when stressed coral expels the colorful algae living in their tissues, turning white. The reef has experienced mass bleaching events in 2016, 2017, 2020, 2022, and 2024. Scientists warn that 90% of the reef could be lost if global temperatures rise 2°C above pre-industrial levels.