As scientific studies continue to reveal how carbon emissions are making the world’s oceans more acidic, one prominent academic from British Columbia suggests that the rapidly changing marine chemistry could also eventually negatively affect the economies of some coastal communities. If the recent collapse of a scallop fishery off the coast of B.C.’s Vancouver Island is any indication, those negative changes may already be well underway.
Karen Kohfeld, a Simon Fraser University associate professor and a Canada Research Chair in Climate, Resource, and Global Change, said scientists have learned much about the oceans’ chemical makeup in the past three decades but are less certain about how the increased acid levels will affect ecosystems.
“There may be some species that adapt better than others,” Kohfeld told DeSmog Canada on Thursday. “And in the end, we are just beginning to understand how ocean acidification could impact our coastal fisheries in the long run.”
Although she noted that carbon dioxide exists in the ocean naturally through rotting plants and dead organisms, Kohfeld said that scientific evidence suggests that oceans have become about 30 per cent more acidic since fossil fuels began being burned in the Industrial Revolution approximately 250 years ago.
If that trend continues, she said, oceans could be between 100 per cent and 150 per cent more acidic by the end of this century.
“That is very alarming,” she said, referring to the relative speed that acid levels are increasing in the world’s oceans, cover more than 70 per cent of the Earth’s surface.
About 40 per cent of atmospheric carbon dioxide ends up in oceans where it dissolves and releases an acid that makes it more difficult for some organisms, notably shellfish, to develop properly. Scientists and media outlets have been reporting recently that scallop and oyster farms in the Pacific Northwest have struggled with the increased acid levels.
Scientist are also concerned with a recent mysterious wasting disease that is killing off numerous species of starfish or sea stars along the Pacific and Atlantic coasts of North America. The illness causes white lesions on the animal’s body before it ruptures, spilling out internal organs.
“The magnitude of it is very concerning,” said Cornell University ecologist Drew Harvell. “There’s the potential that some of these species could actually go extinct.”
Oceans have absorbed approximately 525 billion tons of CO2 from the atmosphere, or about one third of the anthropogenic (human-caused) carbon emissions released both from industrial processes (mostly fossil fuel burning) and changes in land use practices (deforestation and urbanization), the University of Alaska says. “This absorption of CO2 has mitigated warming in the atmosphere, but is having negative impacts on the chemistry and biology of the oceans. When CO2 is added to the oceans it lowers the pH causing the upper ocean to become more acidic.”
Kohfeld said that acidification does not occur at the same rate in the world’s oceans. As an example, she said the ability for organisms to form shells is more difficult in colder waters like the North Pacific compared to waters near the equator because colder temperatures dissolve more carbon dioxide.
“One of the things we are seeing is that acidification is affecting organisms at different life stages,” she said adding she suspects scientists are going to start to see more related impacts on communities dependent on harvesting shellfish.
The California Current Acidification Network website notes “coastal ecosystems are particularly sensitive to three key drivers related to climate change: sea level, ocean temperature and ocean acidification.”
A recent National Climate Assessment (NCA) report in the U.S. said “increasing levels of carbon dioxide from the burning of fossil fuels and other human activities have a direct effect on the world’s oceans.”
The NCA report added “ocean acidification makes water more corrosive, reducing the capacity of marine organisms with shells or skeletons made of calcium carbonate (such as corals, krill, oysters, clams, and crabs) to survive, grow, and reproduce, which in turn will affect the marine food chain.”
The Intergovernmental Panel on Climate Change (IPCC) has reported “ocean acidification poses substantial risks to marine ecosystems, especially polar ecosystems and coral reefs, associated with impacts on the physiology, behavior, and population dynamics of individual species from phytoplankton to animals.”
The IPCC says ocean acidification, along with warming, decreased oxygen levels and pollution “can lead to interactive, complex, and amplified impacts for species and ecosystems.”
Assessing how acidification is changing the world’s oceans is hugely important to the survival of humankind. According to the United Nations, more than three billion people depend on marine and coastal biodiversity for their livelihoods. The UN also says the market value of marine and coastal resources and industries is estimated at $3 trillion per year or about 5 per cent of global GDP.
Some people call ocean acidification “that other CO2 problem,” Kohfeld said, “and it’s an example of how climate change is more than just a higher temperature.”