Ocean acidification is a growing environmental concern that can affect marine ecosystems and economies worldwide. Scientists from the College of the Environment and their many partners operate at the leading edge of this developing field, engaging in research to better understand the fundamentals of ocean acidification and help guide actions to minimize its impacts on ecosystems and society.
What is ocean acidification?
Across the globe, carbon emissions from the combustion of fossil fuels are causing changes to our atmosphere. But it isn’t only our atmosphere that is affected—our oceans are feeling it too through ocean acidification.
Worldwide, the ocean provides an invaluable service to the planet by absorbing about 28% of the carbon dioxide produced by human activities. Once absorbed by the ocean, this carbon dioxide undergoes a series of reactions that change seawater chemistry. As a result, the ocean has become 30% more acidic over the past 250 years.
Why care about ocean acidification?
Ocean acidification threatens how marine ecosystems work, and that matters to people. As ocean acidification intensifies, the carbonate ion—a key component used by animals like corals and shellfish to build their calcium carbonate shells and skeletons—becomes more scarce. In Washington, the acidified waters can become corrosive to microscopic animals—like the larvae of oysters—which are important to the health of our marine ecosystems and to the people who depend on them for food and income. Also, certain plankton that support the ocean food web are affected.
Ocean acidification affects the global ocean
Ocean acidification is happening across the globe, affecting all ocean life from the smallest plankton to the largest of marine mammals.
- In the cold Arctic waters, which naturally hold less calcium carbonate than warmer waters, commercially valuable crabs and shellfish may have trouble building and maintaining their shells.
- In the Antarctic and elsewhere, scientists have discovered that pteropods—a tiny, yet prolific shelled snail that swims and is key in the food web—suffer from dissolved shells in high CO2 conditions.
- In tropical waters, where the carbonate building blocks for corals is relatively high, scientists have shown that carbonate levels are predicted to drop as ocean acidification intensifies.
All of these issues affect how ocean ecosystems function, which has direct consequences on the human communities that depend on their health.
Ocean acidification science: what we know
We know that the ocean’s chemistry has changed and will continue to change.
- Ocean acidification has been well documented through long-term observations spanning decades, and has been attributed to human-generated additions of carbon dioxide to the atmosphere that dissolve into the ocean.
- The average seawater acidity has already risen by about 30% globally in the surface waters of all the ocean basins.
- Natural and human-derived contributions of carbon dioxide combine to cause the effects we observe as ocean acidification.
- Ocean acidification from human-generated carbon dioxide has increased the frequency, intensity and duration of harmful conditions.
These changes are rapid and will continue for decades or centuries and they affect the organisms and ecosystems we care about.
- Small changes in the environment can cause large responses among living organisms.
- Shelled organisms, including oysters and scallops in the Pacific Northwest, are negatively affected. This has consequences for both the marketplace and for ecosystem health, because animals such as oysters help to maintain water quality.
- Sources of food for economically important species are vulnerable. For example, pteropods—small, shelled snails that feed juvenile salmon—are negatively affected by ocean acidification.
These changes matter because they affect the people and economies connected to the ocean, in the Pacific Northwest and across the globe.