A milestone has been reached in the fight against ocean noise pollution. After five years, the International Maritime Organization adopted guidelines to reduce underwater noise from commercial ships.
These are voluntary guidelines, not mandatory code, but their passage is a big deal. If you read this blog regularly, you know how important sound is to whales and other marine life. The ocean, simply put, is an acoustic world, and marine species depend on sound for virtually everything they do to survive: feeding, finding mates, avoiding predators, maintaining social bonds, orienting themselves in the world. But noise from shipping and other human activity has radically altered their environment.
What's most remarkable is the scale of transformation. There are very few places left in the open ocean where shipping doesn't dominate the same low frequencies vital to much of the ocean's wildlife. Background noise levels are now orders of magnitude greater than they were before the advent of mechanized shipping, when whales and other species evolved to use hearing as their primary sense.
In the northeast, according to NOAA and Cornell biologists, ship traffic has made it virtually impossible for endangered right whales to communicate almost 80 percent of the time. Blue and fin whales were once able to communicate across entire ocean basins; now on many days their range is limited to mere miles. In my neck of the woods, ships using the Ports of Seattle and Metro Vancouver contribute to a background din that easily exceeds safe levels for ocean noise proposed a few years ago by the European Commission.
These NOAA maps showing average noise levels in the Atlantic and Pacific Oceans paint the picture: red represents sound around 60 decibels above natural ambient. For biologists, this growing, omnipresent noise is like a smog that is urbanizing the seas, shrinking the sensory range of animals, and unraveling the web of ocean life.
To deal with a problem on this scale, you need international intervention, which is where the International Maritime Organization comes in. For the past six years, NRDC has partnered with NOAA, the Coastal Guard, progressive industry, and academic and research institutions to put noise-quieting on the organization's work plan and shepherd the guidelines that were adopted yesterday through its often byzantine processes.
The new guidelines:
- recognize that shipping noise can have short-term and long-term impacts on marine life, especially on marine mammals;
- call for measurement of shipping noise according to objective, available international standards;
- identify computational models for determining effective quieting measures;
- provide guidance for designing quieter ships and for reducing noise from existing ships, especially by minimizing the roar produced by ship propellers, in a process known as cavitation; and
- advise owners and operators on how to minimize noise through ship operations and maintenance, such as by polishing ship propellers to remove fouling and surface roughness.
The IMO's adoption of guidelines is not the end of the road; indeed, the hard part – implementation – is just beginning. We will have to work with shipping lines, ports, ship classification societies, and governments to put the guidelines into practice and begin pushing back against this worsening global problem.