Pacific reefs heading towards regional collapse from climate change

By Tierney Smith

Climate change caused the total collapse of reef systems in the Eastern Pacific lasting 2500 years, and could be on the verge of doing so again, scientists have warned.

The study, published in the journal Science, shows how natural climatic shifts 4000 years ago stopped reef growth off the coast of Panama for centuries.

The collapse corresponds with dramatic swings in the El Nino-South Oscillation (ENSO), conditions similar to those expected under climate predictions over the next century, say the researchers.

Coral Reefs

Scientists warn of potential collapse of reefs in the eastern Pacific (Source: USFWS Pacific/Creative Commons)

“As humans continue to pump greenhouse gases into the atmosphere, the climate is once again on the threshold of a new regime, with dire consequences for reef ecosystems unless we get control of climate change,” said Richard Aronson, co-author of the study from the Florida Institute of Technology.

The researchers examined the reefs by inserting small-bore aluminium pipes deep into the framework of dead reefs along the Pacific Coast in Panama– pulling out cross sections of the reef structure.

Using these cross sections they were able to reconstruct the history of the reefs over 6,000 years.

The researchers found 2500 years of reef growth were missing from the frameworks and when examining their results with other studies found similar results from reefs in Australia and Japan.

This lack of growth corresponds with a period of strong variability in ENSO – responsible for the El Nino and la Nina climate events – and the researchers say this change is likely to have been responsible for the collapse.

“Coral reefs are resilient ecosystems,” said Lauren Toth, co-author of the report. “For Pacific reefs to have collapsed for such a long period of time and over such a large geographical scale, they must have experienced a major climatic disturbance.”

The researchers warn that scenarios for climate change predicted over the next century echo those experienced 4000 years ago, but say this time the root cause would be human activity over natural occurrences.

However, they note that coral reefs have shown resilience in the past and that recovery could be possible if climate change is mitigated or reversed.

As a recent RTCC article explained urgent action needs to be taken to ensure the one billion people who rely on corals will continue to get the benefit from them.

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