Compromise on Ocean Noise Tests : Science: Scripps promises environmentalists that study of effects of loud signals on marine life will get priority in its research on global warming in the Pacific.

Trying to appease environmentalists, scientists who want to measure global warming by broadcasting booming sounds through the Pacific Ocean have promised to spend at least 18 months primarily studying the effect of the noise on marine life.

Under a compromise between the Scripps Institution of Oceanography and leading environmental groups, the ocean climate research initially will take second place to discovering how whales, elephant seals, sea turtles and other marine creatures respond to high-decibel undersea sounds made by humans.

“This is a very different project than what was originally proposed,” Ann Notthoff, a Natural Resources Defense Council coastal planner, said Monday. “We’ve agreed not to oppose them. We’re hopeful this is going to produce useful results.”

The agreement appears to bring to a close--at least for now--an emotional debate over the noisy intrusion of science into the deep-sea habitat of a variety of endangered species.

The Scripps researchers could begin transmitting their loud, low-frequency rumble 55 miles off the coast of San Mateo County as early as this summer, if state and federal agencies accept the compromise.

Even with the shift in the experiment’s focus, Scripps project manager Andrew Forbes said scientists hope to collect sufficient data from the sound transmissions to conduct useful temperature measurements.

The scientists, led by renowned oceanographer Walter Munk, theorize that they can use deep-water sound waves to measure small changes in the temperature of the Pacific Ocean because sound travels faster when water is warmer.

Scripps’ original plan--to broadcast 195-decibel sounds for 20 minutes every four hours every day--caused an outpouring of controversy last year after some researchers raised concerns that the noise could harm whales close to the ocean-floor loudspeaker or disrupt their normal feeding and mating behavior. Under the new plan, the broadcasts would be less frequent.

Public reaction to the $35-million experiment--funded by the Defense Department--prompted government agencies to hold up the project for more than a year while a detailed environmental study was conducted and public hearings were held.

In recent weeks, Scripps negotiated with a coalition of organizations, including the Natural Resources Defense Council and the Sierra Club Legal Defense Fund, to hammer out a compromise.

Scripps, which had initially proposed studying the effect of the sound on animals as the climate study proceeded, agreed to make the marine mammal research the primary purpose of the project for 18 to 24 months.

With a $4.5-million budget for animal research, the project would be one of the biggest and most elaborate studies of marine mammals conducted by university scientists, Forbes said, with researchers using airplanes, boats and underwater Navy listening posts to study the animals.

In addition to studying the effects of the sound, they also plan to examine the response to noisy commercial ships--a form of noise pollution that some researchers believe is very disruptive to marine creatures.

While the marine mammal study is conducted, oceanographers will monitor the broadcasts as far away as New Zealand to collect data for their global warming research.

Forbes insisted that the climate study will be secondary to the animal research and that the timing and number of broadcasts will be controlled by the animal researchers.

Under the agreement, however, the researchers will stick to 20-minute broadcasts every four hours. The sound pattern will be transmitted less frequently than originally planned, but can be broadcast six times a day for up to four consecutive days.

Scripps has agreed to remove the loudspeaker from the ocean floor when the study is over and find a new spot in an “ocean desert” if the scientists proceed with a second phase of research.

The researchers also agreed to accept representatives nominated by the environmental groups to sit on an advisory board overseeing the marine mammal experiment.

“We’ve responded to the environmental groups’ concerns,” Forbes said.

Nevertheless, some critics were skeptical of the compromise. Lindy Weilgart, a research associate at Dalhousie University in Nova Scotia who first raised the alarm about the test, said the agreement does not go far enough to protect marine life.

A specialist in sperm whales, Weilgart said she favored conducting the marine mammal study using a mobile sound source that would be more effective and less costly. A sound source aboard a boat would not be adequate for temperature measurements, she said, ensuring that the experiment would truly focus on marine mammal research.

“[A mobile sound source is] cheaper, environmentally safe and scientifically more powerful,” she said. “For all intents and purposes, this [compromise] is two years of climate transmissions. I don’t think [Scripps scientists] are losing much by this.”

The Scripps researchers had originally hoped to expand their experiment to all the oceans of the world and conduct the sound tests for 10 years. But Forbes said the controversy over the project has prompted them set a more modest goal.