Say that again? Speak up, I say. Photo via Moon Battery
Of all the consequences that rising levels of carbon dioxide emissions have wrought, this has to be one of the stranger ones: the world's oceans are getting louder. Yes, seas around the globe are becoming physically noisier. Here's how.According to the New York Times, the chemical compounds in seawater that absorb sound have been affected by the increased absorption of atmospheric CO2. Energy from sound waves stimulates certain chemical reactions--and now the greater amounts of CO2 are causing seawater chemistry to change, the result being fewer chemical reactions and less acoustic energy used. And that "means sounds will travel farther and be louder at a given distance from a sound source" at sea.
Which is pretty crazy--CO2 levels are turning the volume knob up on the oceans. And though at first glance, this may just seem to be another 'that's kinda weird' science story, as is usually the case when nature's balance is thrown off, there are repercussions: the increased noisiness could threaten sea mammal populations.
From the Times:
Most of the chemical absorption of sound occurs at relatively low frequencies, from about 1,000 to 5,000 hertz. Propeller noise ... fall in the same range, as does some military and research sonar. So this "background" noise, especially prevalent near shipping lanes, will be louder. That may be bad news for marine mammals, which use sounds in the same range for communication and echolocation while foraging. "We're not saying that during the next 100 years all dolphins will be deafened," Dr. Zeebe said. "But the background noise could essentially override or mask the sounds that they're depending on."Add yet another consequence of ocean acidification, and of rising carbon emissions in general, to the ever growing list--right alongside decaying coral reefs and more marine dead zones. Oh well. Peace and quiet are overrated on the beach anyways--me, I prefer droning white noise wherever I go.