Climate change and coral reefs

That’s Vollmer on the right!

Corals are anal­o­gous to trees in trop­ical rain forests,” said Steve Vollmer, assis­tant pro­fessor at Northeastern’s Marine Sci­ences Center. “They pro­vide the essen­tial habitat for the unprece­dented diver­sity of organ­isms that exist on reefs. If we lose the corals, we will lose our coral reefs.”

So results pub­lished by Vollmer and his col­leagues in Sci­ence Mag­a­zine today bare both wor­ri­some and promising news. The multi-​​institutional team, led by Richard Aronoson of Florida Insti­tute of Tech­nology, ana­lyzed 14 sec­tions of reef off the coast of Panama and found that coral growth lit­er­ally ceased for nearly 2,500 years due to cli­mate change. About 1,500 years ago, how­ever, the reefs began to rebound when cli­mate vari­ability stabilized.

ENSO stands for El Niño-​​Southern Oscil­la­tion, and about 4,000 years ago it was get­ting a bit crazy. “Clues to the past cli­mate are recorded in the geo­chem­istry of sed­i­ments and even coral skele­tons,” said Vollmer. “We can date sed­i­ments and then deter­mine the ratios of ele­ments like tita­nium to pre­dict past ocean tem­per­a­tures.” The team bored 17-​​foot deep cores out of the reef to read the coral bodies and sed­i­ments that had been deposited over mil­lennia. A rel­a­tively thin and unhealthy looking layer betrayed a dif­fi­cult time for the reefs.

Cores from other parts of the Pacific Ocean — including Aus­tralia and Japan — have shown sim­ilar results and have typ­i­cally been attrib­uted to local envi­ron­mental fac­tors. These new results indi­cate that a more global cli­mate problem was at play.

The results are a bit scary, since we are now entering another era of cli­mate change that could have sim­i­larly dev­as­tating effects. But there’s a silver lining: we still may have time to fix things. Even after 2,500 years, the coral reefs that were so man­gled man­aged to revive them­selves when ENSO calmed down. If we can curb our impact on cli­mate change, there’s no reason to think we can’t also min­i­mize the long term impacts we’ll have on our planet.