An international group of scientists led by UCSB researchers demonstrated the effects of carbon dioxide on the acidity of the ocean’s surface. The study’s results indicate that human greenhouse gas emissions play a critical role in ocean pH levels and, consequently, marine habitats.

The findings of the study were recently published in PloS ONE in an article by Paul Matson, a graduate student under ecophysiologist and professor of ecology, evolution and marine biology Gretchen Hofmann. The paper includes contributions from the Scripps Institute at UC San Diego, the Monterey Bay Aquarium, Stanford, UC Santa Cruz and Stazione Zoologica Anton Dohrn of Naples, Italy.

When carbon dioxide enters the atmosphere, one-third is reabsorbed into the oceans where it reacts with water to form carbonic acid. The reabsorption increases the acidity of the ocean, which can stress sea organisms like coral and other marine invertebrates that depend on carbonate to make their skeletal structures.

According to Hofmann, the team’s main objective is to understand the long-term consequences of pH changes in the ocean, particularly in regard to ocean organisms.

“We’ve know for a really long time that ocean interacts with the atmosphere … CO2 dissolves into water, it changes the pH of the water, and changes how organisms make their hard parts” said Hofmann.

In addition, the research aims to answer central questions in the field of ocean acidification, including how rapidly certain parts of the ocean are acidifying and how these increases in acidification will affect species.

To study how greenhouse gases affect pH, the team utilized two types of prototype pH sensors — “SeaFET” and “SeapHOx” — developed by Todd Martz of Scripps.

The sensors were deployed internationally, with locations in Santa Barbara, Antarctica and Tahiti in order to continuously monitor the pH of the surrounding ocean, making it the first time detailed measurements of acidity have been made on such a scale. According to a UCSB press release, the sensors will aid researchers in accurately comparing such diverse collection of measurements.

Yet acidification is only one of many threats to marine creatures. According to Hofmann, there are many factors at play in the decline of invertebrate populations as a result of human activity, which ultimately creates a “multi-stress situation” for these threatened organisms.

Co-author Jennifer Smith of Scripps explained in a report that vast differences in ocean pH worldwide exist and are important for scientists to consider.

“The study is important for identifying the complexity of the ocean acidification problem around the globe. Our data show such huge variability in seawater pH, both within and across marine ecosystems,” Smith said.

The international cooperation lends depth and authority to the study, which have made governments take notice. Hofmann is lead author on the National Climate Assessment and a former member of the National Research Council’s Ocean Acidification Committee. Accordingly, Hofmann said the research may help the U.S. government assess how to better “manage really important natural capital, like the sea urchin diving around [Santa Barbara], which is a huge business.”

In an age of increasing greenhouse gas emissions from cars, power plants and factories, Hofmann and fellow scientists look forward to a more ecologically-conscious era to come as a result of their research.