From CFACT

By Joanne Nova

Everyone was sure that corals would be degraded by our “increasingly acidic oceans” (a political-activist-term for “slightly less alkaline”). But when a team took cores from 200 year old corals in the ocean — instead of studying them for a few months in a laboratory — they discovered some corals have adjusted to the pace of “acidification” much more effectively than anyone thought. The corals actively manage the chemistry of the thin layer of fluid next to the skeleton as the ocean chemistry shifts.

Who would have thought that corals would have the ability to cope with rapid changes in the climate?

In the last 4 million years, corals have only survived 90 or more ice-age cycles.

If only someone had thought to test actual corals at sea before they spent twenty years scaring little children at school?

Thanks to Oldbrew at Tallboke’s.

From the Press Release: Corals are “More resilient than previously thought”

Corals, the foundation of ocean biodiversity, are threatened by climate change. But new research suggests that these organisms might be more resilient than previously thought.

In a study published August 27 in Science Advances, a CU Boulder researcher showed that despite a gradual increase in ocean acidity levels over the past 200 years, some corals seem to be able to adjust and continue to generate their hard, stony skeleton structures.

While it remains unclear how the corals adapted to the changing environment, Hankins said the secret might lie in their calcifying fluid.

“It could be that the processes corals use to modify and regulate their calcifying fluid are more complex than we’ve been able to constrain previously,” said Hankins. “More studies are needed to determine if different species, or if the same species in a different location, have similar responses,” she said.

The ocean absorbs about 30% of carbon dioxide emissions from human activities. As more CO₂ dissolves in the ocean, the seawater undergoes a chemical reaction that makes the ocean surface more acidic. Previous studies suggest that ocean acidity has increased by 40% since the Industrial Revolution and is likely to rise further.

Corals use aragonite, or calcium carbonate to build their skeleton. It turns out that pH of the water is so important that corals don’t leave it up to chance but manage the right pH in the calcifying fluid around the skeleton. Corals build their skeleton in a microscopic compartment between the coral’s tissue and the skeleton. The area is only micrometers thick, and they use proton pumps to get rid of H+ molecules and control the pH themselves.

In the graph below, in part A we can see that the aragonite in the calcifying fluid (Ωcf) has been increasing since about 1840 in the oldest coral. In B the aragonite in the seawater starts to fall rapidly from about 1970 onwards, which ought to “change everything”.  However, in D, despite all that, the annual calcification rate stays remarkably similar.

Just because one study in one type of coral shows that corals may be more resilient than thought doesn’t mean the whole Great Barrier Reef will be fine. But it does show that the experts have been talking out of their hats, whipping up dramas they really didn’t understand.

REFERENCES

Jessica Hankins and Thomas M Decarlo (2025) Multidecadal decoupling between coral calcifying fluid and seawater saturation states, Science Advances, 27 Aug 2025 Vol 11, Issue 35 DOI: 10.1126/sciadv.adr0264

L. E. Lisiecki and M. E. Raymo  (2005) — A Pliocene-Pleistocene stack of 57 globally distributed benthic δ18O records, Paleoceanography 20, 1003

This article originally appeared at JoNova