The print ad, which takes up most of a newspaper page, shouts, "The Ocean Is Evaporating!" TV and Internet spots warn that the world's oceans will disappear - in about a billion years. But what appear to be public service announcements this week, delivered with a fake sternness by Mayor Richard W. Meehan, are actually an ad campaign to encourage visits to the resort town.

"We're advising citizens to book their Ocean City getaway now, before the ocean evaporates," Meehan says in the commercials; the image blurs and jumps like an old newsreel. The ads ran Sunday and Monday in TV markets from Richmond to New York. The Internet version is at http://www.morefunhere.com. The print version ran Monday in The Washington Post. The ads are part of a $1 million campaign designed for the Ocean City Department of Tourism by MGH of Owings Mills.

Earlier this year, while searching for ideas, one staffer read about a study in the Monthly Notices of the British Royal Astronomical Society. The study described how, over hundreds of millions of years, the heat of the sun will steadily increase. After about a billion years, the oceans will boil themselves dry, for reasons separate from climate change. A light went on inside creative director John Patterson's head - an enormous, scorching light. If the oceans boil, he figured, that "probably pretty much ruins things" for Ocean City. It was the start of a joke. Meehan said he felt a little funny making such frightening pronouncements in jest. "Was it kind of Orson-Welles-ish? Yeah," he said, adding that the ads have generated mostly positive responses.

Unfortunately, Ocean City's problems are likely to begin long before the oceans disappear. One of the study's authors, Klaus-Peter Schrder of the University of Guanajuato in Mexico, said in an e-mail to The Post that the earth's warming will make the oceans to expand before they boil. That will turn Ocean City into just Ocean, he says "That beach in the advert will disappear long before the 1 billion years are up," he said.