Ocean Acidification Could Increase by 170 Percent by the End of the Century

Ocean acidification could be a huge issue in the future. But now, a major new international report reveals that an acidic ocean may be closer than we thought. The new findings show that the acidity in the world's oceans may increase by as much as 170 percent by the end of the century, bringing with it significant economic losses.

As levels of atmospheric carbon dioxide (CO2) rise, the gas is beginning to dissolve in the ocean. When CO2 mixes with seawater, though, it forms a mild acid. This is slowly causing the pH of the oceans to decrease, which may drastically impact marine ecosystems. More specifically, a decreased pH can affect shell formation since calcium carbonate, major shell-building material, dissolves with increased acidity.

Now, a group of experts have agreed on "levels of confidence" in relation to ocean acidification statements summarizing the current state of knowledge. They concluded that marine ecosystems and biodiversity are likely to change as a result of this phenomenon, with far-reaching consequences for society. Economic losses from declines in shellfish aquaculture and the degradation of tropical coral reefs may be substantial.

"What we can now say with high levels of confidence about ocean acidification sends a clear message," said Ulf Riebesell, one of the lead authors of the summary, in a news release. "Globally we have to be prepared for significant economic and ecosystem service losses. But we also know that reducing the rate of carbon dioxide emissions will slow acidification."

The researchers discovered that if society continues on the current high emissions trajectory, cold water coral reefs, which are located in the deep seas, may be unsustainable and disappear. Tropical coral reef erosion is also expected to outpace reef building this century. Yet if there are significant emission reductions to meet the two-degree target by 2100, half of the surface waters currently occupied by tropical reefs could remain favorable to their growth.

"Emissions reductions may protect some reefs and marine organisms but we know that the ocean is subject to many other stresses such as warming, deoxygenation, pollution and overfishing," said Wendy Broadgate, one of the researchers, in a news release. "Warming and deoxygenation are also caused by rising carbon dioxide emissions, underlining the importance of reducing fossil fuel emissions. Reducing other stressors such as pollution and overfishing, and the introduction of large scale marine protected areas, may help build some resilience to ocean acidification."

The findings were presented in a summary after the results were gathered from the Third Synopsium on the Ocean in a High CO2 World in California.