A Sea of Change

Ocean Acidification Threatening Coastal Waters

Dr. Christopher Sabine standing next to a CTD rosette.

Dr. Christopher Sabine from NOAA's Pacific Marine Environmental Laboratory standing next to a CTD rosette.

High resolution (Credit: NOAA)

There’s something unexpected happening to our oceans. The chemistry of the seawater is changing due to too much carbon dioxide. It’s called “ocean acidification,” and researchers are now finding evidence of this change in our coastal waterways.

The increasing rate and amount of our carbon dioxide (CO2) emissions is progressively affecting the ocean system, causing the acidity of sea water to increase — a number one priority to many carbon and climate scientists. Researchers at NOAA’s Pacific Marine Environmental Laboratory (PMEL) in Seattle have been studying this global problem for more than three decades and continue to monitor ocean acidification in all the world’s oceans from coral reefs to deep North Pacific waters.

What is Ocean Acidification?

Harvesting oysters.

Harvesting oysters.

High resolution (Credit: NOAA)

Approximately 30 percent of all CO2 released into the atmosphere each year is absorbed by the ocean. While scientists initially focused on the benefits of the ocean’s removing this greenhouse gas from the atmosphere, they began to realize that there was also a downside — so much carbon dioxide has been absorbed that it is actually changing the chemistry of the seawater and affecting many marine organisms.

This “acidification” of ocean water can harm ocean creatures that build calcium carbonate shells — such as oysters and mussels — and can, in turn, affect life all the way up the food web. When CO2 reacts with seawater it creates carbonic acid, lowering the pH of the of the ocean water. At the same time, the reduction in pH also reduces the availability of carbonate ions, which play an important role in shell formation in a number of marine organisms. 

The Effects on Local Economies

Ocean acidification is affecting the entire world’s oceans, including coastal estuaries and waterways. Recently, scientists at PMEL and the University of Washington documented low pH waters in the Puget Sound, which receives water directly from the Pacific Ocean. 

Dr. Richard Feely standing beside the observation buoy.

Dr. Richard Feely standing beside the observation buoy.

High resolution (Credit: NOAA)

“pH values as low as 7.4 were observed in the subsurface waters of Hood Canal and these values are more than 200 percent more acidic than open ocean surface waters,” said PMEL’s Richard Feely, Ph.D. The findings are published in the August issue of Estuarine, Coastal and Shelf Science. Washington state shellfish industries bring in more than $100 million in revenue yearly, and recent declines and mass die-off of oyster larvae are thought to have possible links to ocean acidification.

An Early Warning System

Buoys located off the Washington coast and in Puget Sound will help scientists better understand the changes taking place in the water and may provide an early warning signal should more acidic waters reach oyster beds, enabling the industry to respond accordingly.

The University of Washington, along with the Northwest Association of Networked Ocean Observing Systems and PMEL are developing a regional observing array including a new buoy located off the Washington coast near La Push that was launched in July 2010. The buoy measurements of CO2 in the air and surface water will help determine how much of the gas is being added to Washington waters, enhancing the local acidification. 

Through the Eye of a Needle

In an effort to promote the public’s understanding of atmospheric CO2 in an urban setting, scientists from PMEL partnered with the Pacific Science Center and Seattle’s Space Needle to install an atmospheric CO2 sensor on top of the Space Needle — 605 feet above the Seattle skyline.
“This one sensor is a proof of concept, a prototype, to what we hope we can build as a network of atmospheric CO2 measurements,” said PMEL’s Christopher Sabine, Ph.D.

Stacy Maenner from NOAA's Pacific Marine Environmental Laboratory working on the CO2 sensor on top of the Seattle Space Needle.

Stacy Maenner from NOAA's Pacific Marine Environmental Laboratory working on the CO2 sensor on top of the Seattle Space Needle.

High resolution (Credit: NOAA)

Measurements are made every five minutes and stream the information to PMEL, where the data are processed in real time, posted to the web, and sent to a monitoring station at the Pacific Science Center. “This enables the public to examine the latest data showing the patterns of CO2 variations in Seattle on time scales ranging from minutes to months,” said Sabine.

The Space Needle measurements provide information on how local CO2 emissions are contributing to the global increase in atmospheric CO2 and how they may enhance the acidification of Puget Sound waters.

NOAA and its partners will continue to research and monitor ocean acidification at the local and global levels to help determine the long term consequences of CO2 being taken up by the oceans.

For more information on ocean acidification research, visit the PMEL Ocean Acidification website. NOAA logo.