Coral Reefs, Carbon Dioxide, and Climate Change
How often have you heard that coral reefs are fragile and would be wiped out by global warming?
In 1954 the South Pacific atoll was rocked by a 15 megaton hydrogen bomb 1,000 times more powerful than the explosives dropped on Hiroshima.
The explosion shook islands more than 100 miles away, generated a wave of heat measuring 99,000ºF and spread mist-like radioactive fallout as far as Japan and Australia.
But, much to the surprise of a team of research divers who explored the area, the mile-wide crater left by the detonation has made a remarkable recovery and is now home to a thriving underwater ecosystem.
99,000 degrees Fahrenheit! By comparison the upper-bound estimate for global warming is a puny global temperature increase of 11.5 degrees Fahrenheit (less in the ocean). So even if global warming wipes out life on earth, global warming catastrophists can take comfort that nature will, as it inevitably must, reassert itself.
First of all, I’m relatively certain that the coral at the atoll are not the same coral that died in the nuclear testing.
Second, let’s not forget that the nuclear explosion was a very quick, one-time event. On the other hand, increasing average atmospheric and ocean temperatures is something that is happening over time and lasts much longer. The comparison here is like arguing that The Godfather is unrealistic because Don Corleone couldn’t possibly have died from the increasing cholesterol in his body leading to a heart attack. After all, he had been shot six times and survived!
Third, anyone who is familiar with the impact of pollution on coral reefs knows that the primary concern about carbon dioxide with respect to the reefs is not about temperature and climate change, but rather that increasing CO2 emissions are causing the oceans to become more acidic, which has the potential to cause coral reefs to simply dissolve.
“About a third of the carbon dioxide put into the atmosphere is absorbed by the oceans,” says Caldeira, “which helps slow greenhouse warming, but is a major pollutant of the oceans.” The absorbed CO2 produces carbonic acid, the same acid that gives soft drinks their fizz, making certain minerals called carbonate minerals dissolve more readily in seawater. This is especially true for aragonite, the mineral used by corals and many other marine organisms to grow their skeletons.
“Before the industrial revolution, over 98% of warm water coral reefs were bathed with open ocean waters 3.5 times supersaturated with aragonite, meaning that corals could easily extract it to build reefs,” says [Chemical Oceanographer Long] Cao. “But if atmospheric CO2 stabilizes at 550 ppm — and even that would take concerted international effort to achieve — no existing coral reef will remain in such an environment.” The chemical changes will impact some regions sooner than others. At greatest risk are the Great Barrier Reef and the Caribbean Sea.
The increasing acidification of the oceans is a real problem, and as CO2 emissions into the atmosphere continue, the problem is only going to get worse. Anyone who’s ever owned a salt-water aquarium knows that keeping the pH levels balanced is important, because if the pH gets off, you have a tank full of dead fish.
The ocean is no different. It’s just bigger, and you can’t go to the pet store to restock it.
(If you’re interested in more about the chemistry of ocean acidification, the excellent climate science blog RealClimate has a summary here.)