New study shows increasingly acidic oceans are killing our coral reefs even faster
According to a recent study in Australia's Great Barrier Reef, cuts in carbon emissions are probably the only way we can save coral from ocean acidification.
QUEENSLAND, AUSTRALIA — A study published Wednesday in the scientific journal Nature measured the growth of coral reefs in pre-industrial conditions — when carbon dioxide levels in the atmosphere were much lower. The study showed that the coral grew better in water that mimicked the conditions prior to the Industrial Revolution.
Wednesday’s study led by scientist Ken Caldeira looked at a lagoon in Australia’s Great Barrier Reef. Scientists pumped sodium hydroxide, a base, into the water and brought the water’s alkalinity close to what it was in pre-industrial times. The team of researchers found that the coral grew seven percent faster in the less acidic water.
Scientists have long known that coral’s growth rates worldwide have been slowing down but were unsure of what causes the slowdown. Many factors like warming oceans, pollution and overfishing are known to impact coral reefs. Last week’s study provides evidence that ocean acidification is mostly what’s to blame for the slowdown.
The current chemical makeup of oceans has a pH level that facilitates coral growth. However, just as the chemistry of our skies has began to change, so has the chemistry in the water. Forty percent of the carbon dioxide in Earth’s atmosphere is absorbed by oceans. Once in water, CO₂ forms an acid that has led to higher ocean acidity. As the ocean’s average pH drops, so has the ocean’s tendency to produce calcium carbonate skeletons.
Protecting coral reefs from acidification is crucial. They’re home to 800 coral species and 4,000 species of fish, which is more than 25 percent of the world’s fish species.
Wednesday's study led by scientist Ken Caldeira looked at a lagoon in Australia's Great Barrier Reef. SEAWEB
Researchers surround a tank filled with sodium hydroxide and dye. The sodium hydroxide, a base, returned the water to pre-industrial pH levels. UNIVERSITY OF SYDNEY
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