Though many Texans might not realize it, the Gulf Coast is home to dozens of coral reefs that line the continental shelf. “They’re there,” says Rice University earth, environmental, and planetary scientist Sylvia Dee, who specializes in climate modeling. “They’re just not as shallow as other reefs in the Caribbean.”
Like Australia’s Great Barrier Reef, which, tragically, has lost almost half its coral to global warming, Texas reefs, whose condition is generally considered to be poor to fair, face greater threats by the day. They’ve been in decline since the 1970s, but the past decade has been especially damaging, with large storms, freshwater deluges, fertilizer run-off, algae, and bacteria adding to the threat presented by the reef’s greatest stressors: rapidly rising ocean temperatures and acidification.
If you’ve ever been snorkeling in a place like Jamaica, you have an idea of what Texas reefs look like: full of the same brain-like, spiky, saucer-shaped corals that host a vast array of marine life, from sponges to whale sharks. Some are endangered. Some are hundreds, even thousands, of years old. They not only serve as storm barriers, they’re also vital to the health of our ecosystem and the economy, including Texas fisheries, which produce 83.9 million pounds of seafood annually.
In 2018 Dee joined forces with a group of colleagues from Rice, UT, and LSU to study the future of the Gulf of Mexico’s reefs. Late last year they published their findings in the journal Frontiers in Marine Science, positing answers to questions such as How hot are the oceans likely to get? How stressed are our corals likely to be? And how does that compare with time periods in earth’s deeper geological past?
While the Gulf of Mexico warmed 0.8 degrees Celsius over the past century, Dee explains, it is now projected to warm at a rate of 0.4 degrees Celsius per decade. The team’s study includes climate model simulations that, she says, “all do the same thing when you take the average, right? They all get hotter.” The study predicts that the gulf’s temperature will warm by 2.5 to 3 degrees Celsius by 2100. The average bathwater-y norms will then be 28 to 30.5 degrees Celsius, or 82.4 to 86.9 Fahrenheit—temperatures currently reached only during the depths of summer.
There’s not much evidence from earth’s geological history that our reefs could adapt to such a shift. The only known instances of extremely rapid ocean heating, when the waters were like hot tubs, occurred during mass extinction events. “To be clear,” says Dee, “during those periods of time, everything died.”
Even today’s 86-degree summer temperatures, when combined with other stressors, cause coral to expel the symbiotic algae that supplies its nutrients (and color) from its surface, causing visible “bleaching.” The coral turns white as it begins to starve to death. Reefs usually die off within a year after that occurs, says Dee, but they can also recover if the water cools off again. “But it’s very unlikely that reefs can recover from bleaching,” says Dee, “if the temperatures continue to rise.”
The additional threat of acidity—caused by the oceans absorbing carbon dioxide created by burning fossil fuels and other human activities—prohibits corals from growing their shelly limestone skeletons, known as calcium carbonate. Acidity causes carbonate to dissolve, just like a tooth placed in a can of coke. But there’s at least some good news here, explains Dee. “The rate at which the ocean will become more acidic is not as fast as the rate at which the ocean will warm.”
Yes, we know you’re already having a bad 2020 as it is. But when everything gets back to “normal,” there are things we can do to help. Small actions like reducing red meat consumption, investing in electric vehicles, and taking public transportation will help in the long run, says Dee. “If everyone did it, it would make a difference.”
It’s possible that even all our time spent at home social distancing might just teach us something about climate change, too. Recent reports from China indicate that nitrogen dioxide, also known as air pollution, was reduced by as much as 40 percent during the coronavirus lockdown.
One thing is clear. “We have to move a lot faster than we’re moving now,” says Dee. The Paris Agreement—which aims to limit the rise in global temperatures, keeping the increase to 1.5 degrees Celsius—might not be enough to save the coral in the Gulf of Mexico, and our country isn’t even on board for that.
“Unless we stop or slow down the warming rates in the ocean right now,” warns Dee, “those corals are all likely to be wiped out by end of century.”