The number of days of intense heat waves in the ocean have increased more than 50 percent in the last 30 years and have devastated marine ecosystems when they’ve hit, according to a new study.
Several regions in the Pacific, the Atlantic and the Indian Ocean are particularly vulnerable to the water temperature surges because of their fragile biodiversity and a prevalence of species already at their “warm range edges,” according to the study published Monday in Nature Climate Change.
Coral reefs in the Caribbean, seagrass in Australia and kelp forests off California, all rooted in their environments, have been particularly hurt by heat waves, according to the study. The loss of these “critical foundation species” in an intricate ecosystem can trigger a cascading die-off — that ultimately affects humans — as shelter is destroyed and the food chain is broken.
Lead researcher Dan Smale of the Marine Biological Association in Britain compared the extreme heat to wildfires.
“You have heatwave-induced wildfires that take out huge areas of forest, but this is happening underwater as well,” he told The Guardian. “You see the kelp and seagrasses dying in front of you. Within weeks or months they are just gone, along hundreds of [miles] of coastline.”
The study, which analyzed a broad range of data from other research, noted that “record-breaking events have been observed in most ocean basins in the past decade.” Projections indicate that the heat waves will become “more frequent, more intense and longer lasting throughout the 21st century,” according to the study.
Oceans are bearing the brunt of global warming, absorbing some 90 percent of the heat trapped by greenhouse gases since the middle of the last century, scientists estimate. Areas of sea now suffer the added stress of the heat waves, which are defined as at least five consecutive days when temperatures are abnormally high.
The “absolute temperatures experienced during these events are some of the highest on record” because they’re occurring on already-warmed oceans, Smale told Pacific Standard.
Climate change may be a gradual process, but “more dramatic consequences” can be triggered by “these extreme warming events,” biologist Robert Miller of the University of California, Santa Barbara, who was not involved in the study, told The New York Times.
“In some cases, ecosystems might not be able to recover from those events,” he added. “So the effects of climate change might happen a lot sooner than we expect.”