They found that the reduced acidity increased the corals’ growth rate by about 15 percent, which was itself a striking result. “Ocean acidification is often talked about as this thing of the future,” says Albright. “But it’s already happened. Reefs are already calcifying more slowly today than 100 years ago.”
If that experiment was the ghost of corals past, its sequel with the soda stream is the ghost of corals future. It suggests that even if the pace of acidification continues linearly, corals will fare even worse than they have. The previous century of change reduced their growth by 15 percent; the next century will do so by around 40 percent.
“This is just one study and it needs to be repeated,” says Albright. But if it’s right, it shows that reefs will “get to a tipping point where the system just starts to collapse.” This supports the conclusions from another recent study, which estimated that corals will reach this tipping point before the end of the century. And that’s bad news for the millions of people who depend on those reefs to provide them with food, tourism dollars, and protection from storms.
But Albright’s team subjected the One Tree Island corals to a century’s worth of changing climate in a matter of days. If those changes play out over actual time, could the corals acclimate or adapt? “It’s still an open question,” Albright says. “Overall, the scientific community thinks these changes are happening too quickly. If corals were able to acclimate to the rate we’re changing things, why have we lost 50 percent of our reefs in the past 30 years?”
The Great Barrier Reef, for example, has recently lost more than a quarter of its corals to unprecedentedly bad mass-bleaching events, where high temperatures forced them to evict the algae that they depend on for sustenance. The northern portion was slammed, but the southernmost section, where One Tree Island resides, was largely spared. Still, the reef’s misfortunes gave Albright pause while conducting her experiment. “We caused no long-term impact to this reef,” she says. “At the end, the calcification rates were comparable to what they were at the start. If there had been long-term declines in health, it would have been difficult for me to sleep at night.”
“This is a very important study,” says Abel Valdivia, a conservation biologist at the Center for Biological Diversity. “Globally, coral reefs are being drastically affected by mass-bleaching events. This study suggests that in the near future ocean acidification will considerably reduce the capacity of coral reefs to recover from such events.”
Some coral-reef researchers are now looking at ways of mitigating the disastrous effect of climate change by, say, identifying the sturdiest coral reefs and protecting them, or breeding hardy super-corals. Others feel that such projects are distractions from the only solution that ultimately matters: halting climate change. “I don’t think these things are mutually exclusive,” says Albright. “Ultimately, the solution is reducing global carbon emissions, but we’re not gaining traction in the ways we need to gain traction. Helping reefs in the interim, while we’re garnering political will, is important.”