Climate change causes mass bleaching of coral reefs

Climate change is causing widespread coral bleaching in oceans around the world, a concerning phenomenon with potentially devastating consequences for marine ecosystems. If the elevated water temperatures persist without returning to normal, there are serious concerns about widespread coral reef die-offs and significant environmental damage.

Dereck Manzello, coordinator of Coral Reef Watch at the U.S. National Oceanic and Atmospheric Administration (NOAA), highlighted that more than 54 percent of global reef areas are currently experiencing heat stress at levels that can lead to bleaching. This bleaching, first detected in 1998, has recurred notably in 2010, 2014, 2017, and this year.

The Great Barrier Reef in Australia, the planet's largest coral reef system, has already been hard-hit this year, with approximately 80 percent of its corals affected by bleaching. Off Florida's coast, rapidly rising sea temperatures have caused some corals to die instantly, shedding their tissue without even undergoing bleaching.

There are concerns that this year's bleaching event could set a new record for severity. Manzello, speaking to the Guardian, noted that the area of coral reefs experiencing heat stress is increasing by approximately 1 percent per week, suggesting that a new high could be reached this year.

Although coral reefs cover less than 1 percent of the ocean's surface, they play a crucial role in biodiversity, serving as habitats for a quarter of all marine species. When corals experience high temperatures, they expel the algae living within their tissues, causing them to lose color and cease growth. They also become vulnerable to disease and lose the ability to reproduce when sea temperatures drop.


Jeong-Soo Hong hong@donga.com