Warm ocean waters have hit Australia’s Great Barrier Reef with another mass coral bleaching event, and they are threatening the world’s other coral reefs with the same fate.
Bleaching occurs when the coral turns white after expelling tiny photosynthetic algae in response to environmental trauma such as overly warm or acidic waters, pollution, disease, or habitat destruction. The process itself doesn’t kill coral reefs but the stress it causes leaves them more vulnerable to eventual death.
It’s the third major bleaching event in five years for the Great Barrier Reef, the world’s largest coral reef that is home to more than 1,500 species of fish and 400 species of hard corals. Some call them the “rainforests of the sea” because of their rich biodiversity.
Scientists say this year is seeing the most widespread bleaching yet and they primarily blame climate change, which they say is exacerbated by this year’s El Nino, a naturally recurring warming of ocean currents.
This bleaching could kill part of the Great Barrier Reef, along with coral reefs around the world, according to experts with the National Oceanic and Atmospheric Administration. The extent of the damage will hinge on how warm oceans get in the coming weeks and months.
More than 64,000 people depend on the reef’s tourism economy, according to Australia’s environment minister, Tanya Plibersek. The nation has pledged to spend more than $660 million (U.S. dollars) over the next 10 years to address the problem, including investing in water quality initiatives and endangered species protection efforts.
In the U.S., the total economic value of coral reef services exceeds $3.4 billion annually.
In addition to tourism and recreation, the National Marine Fisheries Service estimates that coral reefs support $100 million worth of commercial fisheries in the U.S.
Experts estimate coral bleaching has killed about one-third of reefs worldwide. When a coral reef is damaged, it can support less wildlife, which leads to less tourism. Local economies also receive billions of dollars in economic impact from recreational fishing trips, diving tours, restaurants, hotels, and other businesses based near reefs.
Also, healthy coral reefs absorb up to 97% of a wave’s energy, creating a buffer that protects people and property in coastal areas during storms and generally helps to prevent erosion.
Bleaching events could stop coral reefs from growing in 10 years if greenhouse gases aren’t significantly reduced, a 2021 study found.