Scientists know that marine life is threatened as the world’s oceans grow more acidic, due largely to increased carbon dioxide in the atmosphere. What they’re less certain of is whether a noticeable improvement could be achieved by curbing the water pollution from coastal wastewater treatment plants, rivers and storm drains that have been shown to increase acidification, or whether cutting global CO2 emissions is the only recourse.
A UCLA-led research team has set out to answer that question by developing a complex west-coast ocean model with $1.6 million in support from the National Oceanic and Atmospheric Administration (NOAA) and the California Ocean Protection Council. The research team is led by Jim McWilliams, the Louis B. Slichter Professor of Earth Sciences in UCLA's department of atmospheric and oceanic sciences and a member of the UCLA Institute of the Environment and Sustainability.
The researchers will spend the next three years examining the increasing acidification of the ocean and decreasing oxygen levels, or hypoxia. The team’s ocean acidification-hypoxia model will include physical and biogeochemical processes to show how the ocean would respond in various scenarios involving climate change, coastal pollution and natural increases in nutrients called nutrient upwelling. The models will include projected impacts on coastal phytoplankton populations and free-swimming sea snails known as pteropods, which are highly susceptible to ocean acidification.
“This is the first time that researchers have attempted this kind of a model, which will help us understand how regional pollution management practices influence local outcomes,” McWilliams said. “If decreasing the local pollutant load causes only a negligible improvement, that means the solution will require a reduction in global greenhouse gas emissions, which is necessary either way.”
McWilliam’s partners include Curtis Deutsch, a former UCLA associate professor of atmospheric and oceanic sciences who is now at the University of Washington, the Southern California Coastal Water Research Project and NOAA’s Pacific Marine Environmental Lab. The NOAA team includes Richard Feely, one of the nation’s leading ocean acidification scientists.
Ocean acidification is already damaging numerous organisms with shells or skeletons containing calcium carbonate and has had severe consequences in the Pacific Northwest shellfish industry. Understanding how big a role coastal pollution plays in this global problem will better inform coastal land management, McWilliams said. The team will examine the area known as the California Current System, which stretches from British Columbia to Baja California and is one of the most biologically productive ocean regions in the world. More than half of the coastal pteropods observed in the California Current System are already experiencing shell dissolution caused by ocean acidification. The UCLA ocean model will help disentangle how climate change, local wastewater and runoff, and natural variation are all contributing to damaging ocean acidification.
“Research indicates that increasing ocean acidity and hypoxia arises from two human activities — greenhouse gas emissions and near-shore nutrient pollution,” said John Laird, California Secretary for Natural Resources and chair of the Ocean Protection Council. “This UCLA-based collaboration between the Ocean Protection Council and NOAA will result in a model that will help us educate the public about changes we can make to reduce the causes of ocean acidification.”
“Climate change is affecting our nation’s coastal and ocean waters, and ocean acidification is a silent but critical product of that change that is rapidly affecting our food security, coastal economies, and culture,” said Russell Callender, acting assistant administrator for NOAA’s National Ocean Service, announcing ugrants for UCLA and two related projects. “However, we’ve been limited by the lack of information on how ocean acidification and nutrient pollution interact. These grants, and the research they will produce, will help us close that gap.”