Acidic oceans boost distance sound travels

MOSS LANDING, Calif., Oct. 2 (UPI) -- A U.S. study suggests the world's increasing ocean acidity is resulting in an increase in the distance sound travels underwater.

Marine chemists at the Monterey Bay Aquarium Research Institute in California said most people know the world's oceans and atmosphere are warming as humans release increasing amounts of carbon dioxide into the Earth's atmosphere. But, the scientists say, fewer people realize the chemistry of the oceans is also changing -- seawater is becoming more acidic as carbon dioxide from the atmosphere dissolves in the oceans.

Scientist Keith Hester and colleagues calculate the ongoing change in ocean acidity will allow sounds to travel up to 70 percent farther underwater. Hester said the greatest effect will be on sounds less than about 3,000 cycles per second -- 2 1/2 octaves higher than "middle C" on a piano.

The researchers say sound already may be traveling 10 percent farther in the oceans than it did a few hundred years ago. However, they predict that by 2050, under conservative projections of ocean acidification, sounds could travel as much as 70 percent farther in some ocean areas, particularly in the Atlantic Ocean.

The study is reported in the journal Geophysical Research Letters.