Ilyina et al. (Nature Geoscience, 2009), from our SOEST, have an interesting paper that claims that the increase in carbon dioxide in the oceans and the resulting decrease in pH can be large enough to significantly change the sound absoption, especially at low-frequency, by the ocean chemical components. In somre regions, the absorption could reduce by 60%. Such changes in sound absorption could have a siginificant impact on marine mammals. One –beneficial?– consequence would be that they could communicate over a larger distances.