Greenhouse gases make oceans noisier




Credit: © IFAW International Fund for Animal Welfare

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ROME: Greenhouse gases worsen ocean noise by raising acidity levels and causing sound to travel farther, making it ever harder for marine mammals to communicate, UN and wildlife experts said on Wednesday.

"Acidity is a new, strange and unwanted development... for a whole range of marine animals," Mark Simmonds of the Whale and Dolphin Conservation Society told a news conference.

Simmonds, the society's scientific director, was speaking as the UN Convention on the Conservation of Migratory Species (CMS) began three days of debate on a resolution aimed at combatting ocean noise, which is caused primarily by shipping, oil and gas exploration and military sonars.

"Noisy activities are producing an acoustic fog that prevents whales from maintaining social groups, finding each other for breeding purposes, and so forth," Simmonds said.

The Monterey Bay Aquarium Research Institute in California, which is studying the rising acidity of seawater, says on its website: "As the oceans become more acidic, sounds will travel farther," notably low-frequency sounds "used by marine mammals to find food and mates."

Legal expert Veronica Frank of the International Fund for Animal Welfare said ocean noise has doubled each decade for the past 40 years and is expected to keep increasing.

"Blue whales' capacity to communicate has been reduced by 90 percent," she said.

The proposed resolution would urge the 110 parties to the CMS to mitigate the impact of ocean noise on vulnerable species, assess the environmental impact of sound-producing activities and avoid the use of high-intensity naval sonars that could pose risks for marine mammals.

The issue of ocean noise is an "international hot potato" because of the commercial and military interests involved, Simmonds said.

One study found that sounds from seismic surveys using powerful airguns travelled more than 3,000 kilometers from the source, the UN Environment Programme said in a communique.

Sound naturally travels farther in water than air because water has more mass.