Marine heatwaves, which have become more frequent, intense, and have been staying longer, are playing a huge role in coral death, says new research from scientists working at the Great Barrier Reef.
Researchers knew these heat waves were a big contributor to coral degradation, or bleaching, but were surprised to learn how rapidly coral also dies off during a heatwave. When degradation occurs, coral can often regenerate when ocean temperatures level back out, but these ocean heat waves appear quicker and linger longer causing the coral to dies off completely.
“Now, we see there is also a temperature at which the coral animal itself suffers from heat-induced mortality. This isn’t starvation, this is the animal itself undergoing mortality directly from the heat of the water,” says Tracy Ainsworth, a marine biologist at the University of New South Wales.
According to BBC, these heatwaves are a byproduct of the climate crisis.
This study derives from two coral species that were affected during the 2016 marine heatwave that caused at least 90 percent of Australia’s Great Barrier Reef to experience some degree of bleaching.
“Climate scientists talk about ‘unknown unknowns’ — impacts that we haven’t anticipated from existing knowledge and experience. This discovery fits into this category. As we begin now to understand this impact, the question is how many more of these ‘unknown unknowns’ might there still be that could bring faster and greater damage to coral reefs from climate change,” says James Heron, a scientist at James Cook University.