The news on coral reefs alternates between doom and hope. Reefs are among the most fragile ecosystems on the planet and essential to marine life. They are also highly sensitive to climate change and are dying at a dramatic rate.

By the century’s end, virtually every reef in the ocean will suffer annual life-threatening bleaching events, according to a report published earlier this year in Nature’s Scientific Reports. Australian scientists who surveyed the Great Barrier Reef last month now say the world’s largest coral reef system, which lost about a fourth of its coral last year in its worst-ever bleaching event, faces another bleaching problem this year that could be even worse. A paper published Thursday on the