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Research: ocean acidification varies around North America
Monica Allen

Research: ocean acidification varies around North America

With hot spots found in northeast and west coast waters

New NOAA and partner research comparing ocean acidification around North America shows that the most vulnerable coastal waters are along the northern part of the east and west coasts.

While previous research has looked at specific regions, the new study appearing in Nature Communications, is the first in-depth comparison of ocean acidification in all North American coastal ocean waters. 

“Ocean acidification is everywhere, but this synthesis basically shows that, depending on the location, it can manifest very differently,” said Wei-Jun Cai, lead author and a professor at the University of Delaware School of Marine Science and Policy. 

Measuring ocean acidification

Measuring ocean acidification

Ocean acidification buoy in the Gulf of Mexico. Credit: NOAA

Ocean acidification, a global process in which the ocean absorbs carbon dioxide from the atmosphere, is occurring faster than at any time in the past 50 million years. The global rise in ocean acidity is fueled by human-created greenhouse gases. An estimated 25 percent of those emissions are absorbed by the ocean.

In the ocean waters off the United States east coast, the northbound Gulf Stream current brings warm waters from the tropics while the southbound Labrador Current brings cold waters from the Arctic and subarctic regions. The colder ocean temperatures along the northern part of the east coast take up more carbon dioxide from the atmosphere than do warmer waters along the southern east coast and Gulf of Mexico. This uptake of carbon dioxide accelerates ocean acidification, which can hamper the ability of shellfish, corals and other valuable marine species to build their shells and thrive.

On the west coast, ocean acidification is affecting the waters of the California Current, which extends from the United States - Canadian border to Baja California. The California Current is characterized by strong, cold currents, and wind-driven upwelling events. Upwelling brings colder, carbon-dioxide-rich subsurface waters to the ocean’s surface to replace surface water that has been pushed away by winds.

West Coast survey

West Coast survey

NOAA Ship Ronald H. Brown lowers a conductivity, temperature, depth instrument into the Pacific as part of the West Coast mission to measure acidification in 2016. Credit: NOAA

“The water from the subsurface has low pH and high carbon dioxide, which causes stress to the biological system,” said co-author Richard Feely of NOAA’s Pacific Marine Environmental Laboratory (PMEL). “So the combination of the uptake of anthropogenic carbon dioxide from the atmosphere and the upwelling of CO2-rich low-pH water from below leads to enhanced acidification in this region.”

The research team from NOAA, the University of Delaware, and scientists from Canada, Mexico, the United Kingdom, China and Taiwan based the new findings on data gathered during several research cruises between 2007 and 2018. A number of those cruises were led or supported by NOAA’s Pacific Marine Environmental Lab, Atlantic Oceanographic and Meteorological Lab and the Ocean Acidification Program.

For more information, please go online to read the news release from the University of Delaware.

Please go online to read the paper in Nature Communications: Controls on surface water carbonate chemistry along the North American ocean margins

For more information, please contact Monica Allen, NOAA Communications,, 202-379-6693



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Oceanic and Atmospheric Research (OAR) - or "NOAA Research" - provides the research foundation for understanding the complex systems that support our planet. Working in partnership with other organizational units of the NOAA, a bureau of the Department of Commerce, NOAA Research enables better forecasts, earlier warnings for natural disasters, and a greater understanding of the Earth. Our role is to provide unbiased science to better manage the environment, nationally, and globally.


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