Ocean Acidification Could Increase 170 Percent by 2100

Researchers from the International Geosphere-Biosphere Program (IGBP) contend that acidification in the world's oceans is poised to rise by as much as 170 percent by the end of the century.

The research group, which studies the phenomenon of global change, is under the umbrella of the International Council of Scientific Unions, a large coordinating body of national science organizations.

The IGPB reports that marine ecosystems and biodiversity are likely to change as the oceans acidify, and the consequences, many of which are economic, could ripple throughout society. Some of the impacts the research group suggests could happen are a decline in the shellfish industry and the degradation of coral reefs, which are often big draws for tourism.

"What we can now say with high levels of confidence about ocean acidification sends a clear message. 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," said Ulf Riebesell of the GEOMAR Helmholtz Centre for Ocean Research in Kiel, Germany.

The IGPB warned that if current emissions trends continue, it could could spell the end of many tropical coral reefs, as their erosion from acidification will outpace the natural reef-building process.

However, the group said if there are significant emissions reductions by 2100, it could stave off about half of the projected reef loss.

"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, Deputy Director of the IGBP. "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 IGBP has issued the following 21 statements on ocean acidification with varying confidence levels:

Very high confidence

• Ocean acidification is caused by carbon dioxide emissions from human activity to the atmosphere that end up in the ocean..
• The capacity of the ocean to act as a carbon sink decreases as it acidifies.
• Reducing carbon dioxide emissions will slow the progress of ocean acidification.
• Anthropogenic ocean acidification is currently in progress and is measurable.
• The legacy of historical fossil fuel emissions on ocean acidification will be felt for centuries.

High confidence

• If carbon dioxide emissions continue on the current trajectory, coral reef erosion is likely to outpace reef building some time this century.
• Cold-water coral communities are at risk and may be unsustainable.
• Mollusks (such as mussels, oysters and pteropods) are one of the groups most sensitive to ocean acidification.
• The varied responses of species to ocean acidification and other stressors are likely to lead to changes in marine ecosystems, but the extent of the impact is difficult to predict.
• Multiple stressors compound the effects of ocean acidification.

Medium confidence

• Negative socio-economic impacts on coral reefs are expected, but the scale of the costs is uncertain.
• Declines in shellfisheries will lead to economic losses, but the extent of the losses is uncertain.
• Ocean acidification may have some direct effects on fish behavior and physiology.
• The shells of marine snails known as pteropods, an important link in the marine food web, are already dissolving.