Waving, Not Drowning: How Some Coral Reefs Will Survive Climate Change

Todd Woody, Takepart.com Yahoo News 24 Jul 15;

The news about the world’s oceans seems to be unrelentingly bad—predictions of terrifying sea-level rise, increasing acidification that threatens to wipe out the phytoplankton that supports nearly all marine life, and starving whales.

Now, a new study offers hope that some coral reefs will survive rising temperatures and oceans. As water temperatures increase and the oceans become more acidic, coral reefs around the world are dying. Others face death by drowning as sea levels rise. But scientists studying coral reefs surrounding Palau, an archipelago in the western Pacific Ocean, have found that they are managing to grow at a rate that keeps pace with sea-level rise. As long as sea-level and temperature increases remain moderate, the coral reefs, also called micro atolls, are likely to survive until the end of the 21st century, the researchers concluded.

So, Why Should You Care? The oceans are absorbing growing amounts of carbon dioxide produced by the burning of fossil fuels, and the resulting acidification could cost the global economy $1 trillion a year by 2100 as coral reefs disappear, according to a United Nations report released last October. Tropical coral reefs and the plethora of fish and marine life that depend on them provide jobs and sustenance to some 400 million people.

In Palau, scientists measured 570 micro atolls in 10 locations around the archipelago and found “vertical skeletal extension” of the reefs over the past six to eight years. That growth rate matched recent sea-level rise, which created the space for the coral reefs, called Porites, to expand.

“Despite recent declines in calcification over the past decades, massive Porites are relatively resilient to both decreasing pH and increasing temperature, representing ‘winners’ under future climate-change scenarios,” the scientists wrote in the study, which was published Wednesday in the journal Royal Society Open Science.

There is a limit to that resilience, however. If greenhouse gas emissions continue unabated, the result will be the “complete impairment of micro atoll growth by 2050…and reef flats will not be able to keep up with rising sea levels,” according to the paper.

Robert van Woesik, lead author of the study and a professor of biological science at the Florida Institute of Technology, said it was uncertain whether the findings would apply elsewhere.

“I have no evidence from other locations in the Pacific Ocean, but I will say that Palau has an exceptional conservation history, and local protection certainly matters,” he wrote in an email.

The micro atolls play a crucial role in protecting Palau’s low-lying archipelago from tropical storms, as well as providing habitat for fish and other marine life.

“If coral reef growth cannot ‘keep up’ with sea-level rise, these natural island storm barriers will disappear, resulting in inundation and reductions in the habitable land for millions of people throughout the Pacific Ocean,” van Woesik and his colleagues wrote in the study.