Low frequency sound absorption in the Arctic Ocean: Potential impact of ocean acidification

Abstract

The principal mechanism for low frequency absorption in seawater is a boron reaction that is pH dependent; the lower the pH, the lower the absorption. Twenty seven years ago, Mellen et al. [J. Acoust. Soc. Am. 82, S30 (1987)] computed the low frequency sound absorption for the Arctic Ocean. Since the time the carbon dioxide (CO2) level in the atmosphere has been continually increasing. Experts predict that the resulting ocean acidification may increase by up to 170% this century. Acoustically, the Arctic Ocean is most sensitive to rapid change not only because the cold water readily absorbs CO2, but also because the sound channel axis is at or near the surface. The range of reduction in the low frequency sound absorption is presented based on possible future acidification scenarios, mindful that this is just one component of a complex evolution that is occurring in the Arctic.