New measurements show the problem is spreading

Jan 21, 2010 10:30 GMT  ·  By

A new scientific research that looked at large swaths of the Pacific Ocean has determined that the body of water is becoming increasingly acidic as the years pass. Researchers at the University of South Florida (USF) College of Marine Science analyzed water from various locations and depths in the Pacific northeast, and determined that the level of carbonic acid in the water was more elevated than determined in previous investigations, PhysOrg reports.

The team compared its results with readings obtained in other investigations, carried out in 1991 and 2006. The recent investigation is therefore the first one ever to produce direct evidence of ocean-wide acidification throughout the Pacific basin. Seawaters between Oahu, Hawaii, and Kodiak, Alaska were analyzed, with experts sampling seawater randomly and testing its pH value. The lower these values, the more acidic a liquid is. Water is generally thought to be a neutral solution, with a pH of about 7. Values higher than that correspond to basic, or alkaline, solutions.

USF seawater Physical Chemistry Professor Robert Byrne was the principal investigator of the research. He reveals that the acidification is largely caused by increased amounts of dangerous greenhouse-gas carbon dioxide (CO2) in the planet's atmosphere. Human activities, such as burning fossil fuels and flying aircraft, are widely considered to be the main source of this type of gases, he adds. “If this happens in a piece of ocean as big as a whole ocean basin, then this is a global phenomenon,” Byrne says. When CO2 interacts with water, large amounts of carbonic acid are produced, which gradually change the overall pH levels of the oceans.

“The pH decrease is direct evidence for ocean acidification of a large portion of the North Pacific Ocean. These dramatic changes can be attributed, in most part, to anthropogenic CO2 uptake by the ocean over a 15-year period,” cruise chief scientist and research team member Richard Feely adds. He also holds an appointment at the US National Oceanic and Atmospheric Administration's (NOAA) Pacific Marine Environmental Laboratory, in Seattle. The investigation was a part of the Climate Variability and Predictability/CO2 Repeat Hydrography Program, which is being sponsored by the NOAA-Office of Global Programs and the Division of Ocean Sciences at the US National Science Foundation (NSF).

“Estimates of future atmospheric and oceanic CO2 concentrations, based on the Intergovernmental Panel on Climate Change (IPCC) emission scenarios and general circulation models, indicate that by the middle of this century atmospheric CO2 levels could reach more than 500 ppm [parts per million], and near the end of the century they could be over 800 ppm. Current levels are near 390 ppm, and preindustrial levels were near 280 ppm,” Feely adds.