Once-silent Earth now a cacophony

The chirp of satellites and the rumble of vessels are disturbing

A mere half-century ago, the music of nature rang out largely unmolested. Whales, dolphins, and turtles crooned their eerie songs and distant galaxies spewed out their radio signals bearing information from the big bang and the great beyond.

Not so today. In short order, mankind has raised such a ruckus that if the planet were a party, Mother Nature would have to call the cops.

The incessant chirp of radio waves from communications satellites has grown so pervasive that astronomers claim it interferes with their radio telescope observations. Marine biologists say the throb of supertanker propellers creates such a din that whales, dolphins, and other sea creatures are at risk.

"These things have gradually built up without people taking too much interest in whether or not the noise is affecting the natural system," says Sylvia Earle, the explorer in residence for that National Geographic Society and an oceanographer. "To be so arrogant to think that we can do anything with the skies above or the seas below without studying the consequences is inexcusable."

To be sure, radio waves and sound waves are very different. When radio astronomers refer to noise, they mean local radio interference that blocks out signals from outer space. When marine biologists refer to noise, they mean sound waves that physically vibrate and can even damage living tissues but are not part of the electromagnetic spectrum like radio waves.

But both types are symptoms of technological progress and economic development.

In the seas, the size and tonnage of the world's merchant fleet has skyrocketed to service growing global trade. This has led to increases in shipping noise, particularly near big ports like San Francisco and New York. While oil prospectors in the past drilled with maps and a hunch, they now use high-tech airguns that blast sound waves deep into the Earth to detect likely deposits of crude.

Navies around the world are developing deep ocean sonar systems that broadcast sound waves in their search for submarines, often in wavelengths used by whales for communication. Scientists have also set up underwater "boomboxes" to gauge ocean temperatures and test for global warming by measuring the speed of sound waves through seas.

"The issue is acute in the ocean because sound travels better in water," says Joel Reynolds, director of the Natural Resource Defense Council's (NRDC's) Marine Mammal Protection Project. "It's not really a visual world, so animals have adapted to use of sound for crucial tasks like identifying food sources...."

Some environmentalists believe mass whale beachings and increased rates of marine mammal mortality are directly attributable to louder oceans. Others worry that underwater noise is interfering with communications of whales and other creatures in the same way that car horns hamper human conversation.

According to the NRDC, the amount of ambient noise in the ocean may have increased by 10 decibels - in other words, 10-fold - between 1950 and 1975.

In the skies, new constellations of communications satellites broadcast radio waves on frequencies very close to those used by big radio telescopes to study distant galaxies. Dozens more of these satellites are scheduled for launch as the demand for cell phones and global communications increases.

Despite efforts by telecommunications companies to protect bandwidths that hold crucial astronomical information, the volume of satellites threatens to overwhelm astronomers. Such is the case with Motorola's Irridium satellites. Signals from this global network allowing callers to phone home from virtually any point on Earth bleeds into an observation bandwidth for hydroxide molecules, a crucial in element in star formation.

"When a communications satellite passes overhead, it can be like setting off dynamite in someone's living room," says Seth Shostak, a radio astronomer with the Search for Extraterrestrial Intelligence Institute. According to Mr. Shostak, the repetitive radio signals from satellites and space probes mimic what scientists expect to be characteristics of a transmission from aliens. This will make it difficult to pick out such signals.

But prospects for mitigating noise in space and in the oceans are slim at best. Demand for bandwidth seems insatiable as communication becomes even more important for more people.

In the seas, regulating Naval shipping traffic or oil prospecting seems a Herculean task that would require cooperation from diverse states, some of which are unfriendly to the West. Although some of the corporations that ply these trades have shown interest in turning down the volume, their shareholder interest is paramount and serious mitigation could be very expensive.

Furthermore, the basic understanding of how noise affects sea creatures is flimsy at best, and everyone agrees that more research needs to occur before sound policies can be implemented. The National Marine Fisheries Service is putting together a proposal for expanded noise regulation in US waters, which would be a start but would still fail to address the global aspects of the problem.

But the greatest fear is that these policies and protections, if they arrive at all, will be too late both above and below. "I suspect there will be some point where no matter how inventive we are it may become impossible to sort out the signals we are looking for," says Shostak. "At that point, all you can do is move the whole project to the back side of the moon."