CO2 could worsen whales’ sonar

by Amy Judd | October 9, 2008 at 09:38 am

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Whales already have to contend with military sonar excercises to hear each other, but yesterday it was revealed that the burning of fossil fuels could be making the problem worse for them.

Increased carbon dioxide in the atmosphere causes ocean acidification and this affects the whales' ability to hear because the amount of sound that can be absorbed partly depends on the water's PH. But now scientists are combining these two elements to see what the results will be.

Their paper, “Unanticipated consequences of ocean acidification: A noisier ocean at lower pH,” published last week in the journal Geophysical Research Letters, found that fossil fuels are turning up the ocean’s volume. Since the beginning of the Industrial Revolution, the overall pH of the world’s oceans has dropped by about 0.1 units, with more of the changes concentrated closer to the poles. The authors found that sound absorption has decreased by 15 percent in parts of the North Atlantic and by 10 percent throughout the Atlantic and Pacific

As Discovery News notes, these values are probably underestimated because they are based only on atmospheric CO2 absorbed into the ocean, and not on any other factors that could increase the acidity of the seawater.

And unless we curb our fossil fuel use, it’s only going to get louder down there. The Intergovernmental Panel on Climate Change concluded that unless carbon dioxide emissions are curbed, the ocean’s pH will drop about another 0.3 points by midcentury. This increase in acidity, say the authors, could decrease absorption by almost 40 percent, and sound could travel up to 70 percent farther.

It is known that noise levels in the ocean are only going to get worse due to the combined effects of less absorption from an unbalanced PH and an increasing of mankind's activities.