Ocean acidity, Hester said, is projected to increase by .3 pH points between now and 2050. That may not seem like much, but the change will spur a 70 percent increase in the distance sound will travel.
"We were surprised to see how big it was," Hester said.
Less certain are the ramifications.
Previous studies have suggested that high-powered sonar may cause hearing loss and other injuries to marine mammals.
Recent findings have revealed that reef fishes use sound to locate their reefs.
In addition to animal impacts, military sonar operators may have more trouble distinguishing faint signals from background noise.
The new study appeared this week in in the journal Geophysical Research Letters.
"Impossible to Predict"
Marine biologists are cautious about predicting about what may happen to marine animals in seas that conduct sound better.
"The effects on biology are uncertain at the moment," Richard Zeebe of the University of Hawaii said in an email.
But it's clear that the change in sound transmission is an unanticipated side effect of fossil fuel burning, experts say.
"This is a good example that we're making very big changes to our oceans," said co-author Hester.
"There's a hundred million tons of carbon dioxide absorbed per hour by the oceans. This is really changing a lot [of things] that we're still trying to understand."
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