Half of the world’s coral reefs have died in the last 30 years. Now scientists are racing to ensure that the rest survive.
The threat to coral reefs “isn’t something that’s going to happen 100 years from now. We’re losing them right now,” Julia Baum told the Associated Press. She is a marine biologist at the University of Victoria, in British Columbia, Canada. “We’re losing them really quickly, much more quickly than I think any of us ever could have imagined.”
Even if global warming were to stop right now, scientists predict that more than 90% of corals will die by 2050. If no major steps are taken to address the issue, the reefs may be headed for total extinction.
Why Reefs Matter
The planet’s health depends on the survival of coral reefs. They are often described as underwater rainforests, because they are ecosystems that provide habitats for one in four of all marine species. In addition, the reefs serve as barriers that protect coastlines from the full force of powerful storms.
Corals are used in medical research for cures to diseases, including cancer, arthritis, and viral infections. They are key to local economies, as well, since the reefs attract tourists, the fishing industry, and other businesses, bringing in billions of dollars of revenue.
“To lose coral reefs is to fundamentally undermine the health of a very large proportion of the human race,” Ruth Gates, director of the Hawaii Institute of Marine Biology, said.
Corals are invertebrates, or animals that lack a backbone. They live mostly in tropical waters. The corals release a substance called calcium carbonate, which forms protective skeletons around them. The skeletons grow and take on vivid colors. This is the result of the corals’ symbiotic, or mutually beneficial, relationship, with algae that live in their tissues and give them energy.
But corals are particularly sensitive to changes in temperature. A rise of just 1 to 2 degrees Celsius (1.8 to 3.6 degrees Fahrenheit) can force the corals to drive out the algae. Then the corals’ skeletons turn white in a process called “bleaching.” Corals can survive in these higher temperatures only for a few months.
Feeling the Heat
The problem for the reefs increased dramatically during a recent extended El Niño weather phenomenon. During El Niño, a warming of the central Pacific Ocean interacts with the atmosphere, causing a change in weather across the globe. In 2015-2016, the longer El Niño warmed the Pacific near the equator, which led to the most widespread bleaching of coral reefs ever recorded. This bleaching event continues to plague the world’s reefs.
In the Indian Ocean, near the islands of the Maldives, about 73% of the coral reefs suffered bleaching between March and May 2016, according to the country’s Marine Research Center. Areas in the central Pacific were hit the hardest—about 90% of the reef was destroyed in the waters of the Republic of Kiribati.
To make matters worse, scientists are expecting another wave of warmer ocean temperatures starting next month. The conditions may not be as severe as they were last year. But Mark Eaken, coordinator of the National Oceanic and Atmospheric Administration’s Coral Reef Watch, said that the higher temperatures could stress “reefs that are still hurting from the last two years.”
And the problem is not just global warming. The reefs have also been affected by pollution, coastal development, and overfishing.
Scientists remain hopeful that it’s not too late to save the reefs, and some are moving ahead on experiments to accomplish that goal.
Gates, for example, is trying to “train” corals to get used to rising temperatures by exposing them to survivable levels of heat stress. She hopes that the corals will “somehow fix [the experience] in their memory” so they can endure similar stress in the future.
“It’s probably time that we start thinking outside the box,” she said. “It’s sort of a no-win game if we do nothing.”