Ocean Acidification

Our vast, blue ocean nurtures and feeds the Earth’s natural systems. It provides a home to the world’s largest habitat and creates its weather by interacting with the atmosphere.

The ocean also controls our planet’s temperature by absorbing the greenhouse gas carbon dioxide, providing a buffer from the effects of atmospheric climate change.

But that dissolved carbon dioxide has lowered seawater’s pH, which measures its acid or base level. Ocean pH has dropped from 8.21 to 8.10 since the mid-1700s when industrial activity and an increase in carbon dioxide output began. Seawater remains on the basic side of the pH scale; it’s unlikely it will ever become acidic. But the small changes have bigger consequences, which many believe can be fixed — if the will exists.

The National Oceanic and Atmospheric Administration has concluded that over the past 300 years atmospheric carbon dioxide concentrations have increased from 280 to 385 parts per million. “The oceans have absorbed approximately 525 billion tons of carbon dioxide from the atmosphere, or about one third of the anthropogenic carbon emissions released,” says a NOAA statement.

“This absorption has benefited humankind by significantly reducing the greenhouse gas levels in the atmosphere and minimizing some of the impacts of global warming. However, the ocean’s uptake of carbon dioxide is having negative impacts on its chemistry and biology….”

In seawater, carbon dioxide forms carbonic acid. This chemistry makes it harder for corals, plankton and tiny marine snails to form their body parts. It threatens not only coral reefs, but also other marine life moving up the food chain from plankton.

In October 2008, a panel of 155 scientists from 26 countries met in Monaco to discuss oceanic chemical changes. “Severe damages are imminent,” the panel said in the Monaco Declaration. “Ocean acidification may render most regions chemically inhospitable to coral reefs by 2050.” The recently touted strategy of “fertilizing” the oceans to encourage the growth of tiny marine plants that take up carbon dioxide may actually make the problem worse, according to the panel.

In November 2008, Timothy Wootton, a biologist at the University of Chicago, led a team working off the northwestern coast of Washington state. They found that acidity had increased at least 10 times faster than predicted by climate models. While they discovered that larger shellfish suffered and smaller species did better, the team’s overall conclusions were troubling.

But there is hope. People are great innovators, and an unprecedented amount of focus and talent is being directed at the challenge of climate change and therefore ocean acidity. “The mass extinction of corals and other marine life is unacceptable and unnecessary, and we can prevent it if we act quickly,” said Jacqueline Savitz of the international ocean conservation group Oceana.

Reducing the carbon dioxide released into the atmosphere can reduce what’s absorbed in the ocean, slowing acidification. There are also schemes to store carbon dioxide in places other than the ocean. Atmosphere, ocean and land are linked, and human activities influence all three, hopefully for the better.

You can learn more about the research at www.ocean-acidification.net and the basic issues from Oceana at www.oceana.org/climate/impacts/acid-oceans.

Dan Haifley is the executive director of O’Neill Sea Odyssey. He can be reached at dhaifley@oneillseaodyssey.org.

Santa Cruz Sentinel, 21 February 2009. Article.