In this era of globalization, restaurant menus from New York to San Francisco boast fresh fish with distant origins: blackfin tuna from Tobago, mahi-mahi from Hawaii and black grouper from the Bahamas. But a group of chefs and food service vendors (aware that such jet-setting comes at a heavy environmental cost) is promoting a radical shift in practice: Increase the amount of fish that is frozen at sea so it can be transported by ship or truck instead.

Culinary leaders who care about reducing greenhouse gases linked to global warming need “to get people to understand that frozen is fresher than raw” most of the time, according to Food Network host Alton Brown. “What we need is more trains,” he added. “There needs to be a fish train.”

Although the idea of a “fish train” might sound like a fantasy, Brown is making a serious point: Bon Appetit Management, which operates 400 cafes nationwide, estimates that shipping seafood by air generates 10 times as much greenhouse gas as transferring it by container ship and five times as much as shipping by truck.

“If it’s frozen at sea and handled right, properly, we can live with it. There’s not a difference,” said the company’s chief executive, Fedele Bauccio, addressing a crowd at the Monterey Bay Aquarium’s Cooking for Solutions 2008 sustainable-foods conference in May. “We have to get consumers behind us, to make a difference in what we eat.”

Bon Appetit announced in April it was embarking on a “Low-Carbon Diet” to reduce its operation’s climate impact. As part of its pledge, the company vowed to stop serving air-freighted fish by April 2009 and to adopt new procurement standards that prefer “regionally procured or frozen-at-sea” wild seafood.

Transporting what we eat accounts for 80 percent of the U.S. food system’s greenhouse gas emissions, according to scientific studies, and the average American’s eating habits account for 2.8 tons of carbon dioxide emissions each year, compared with the 2.2 tons of carbon dioxide the same person generates by driving.

Traditionally, frozen-at-sea products have served the commodity market. Producers who operate floating factories have caught, processed and frozen such species as pollock to make fish sticks and other inexpensive items. But with technological advances, high-end frozen products, either processed on a boat or frozen on the dock within a few hours of being caught, are making their way onto menus at white-tablecloth restaurants, where fresh fish usually occupies a place of honor.

Barton Seaver, who until recently was executive chef at Washington’s Hook and Tackle Box restaurants, said he buys products such as Marine Stewardship Council-certified bay scallops from Argentina. The scallops “are shucked and frozen within 10 minutes of being pulled out of the sea. They are a fantastic product, and the freshness is unbeatable,” said Seaver.

Some chefs have it easier than others. Dory Ford, executive chef of Bon Appetit’s cafe at the Monterey Bay Aquarium and a leader in the sustainable-seafood movement, estimates that 90 percent of his seafood comes from the Pacific, some of it from just a few miles from his restaurant. “I’m in a unique position because I’m located on an ocean,” Ford said in an interview. “As a population we’ve gotten so used to getting whatever we want, whenever we want. So we’ve lost touch with where we are, locally.”

Although several prominent chefs and caterers have embraced the idea of using more frozen fish, not everyone wants to. Kona Blue Water Farms President Neil Sims, whose Hawaii-based company farm raises a yellowtail it has dubbed “Kona kampachi,” sells to Hook and other high-end restaurants in cities including Los Angeles, Chicago and Dallas. Those places pay for Kona Blue to ship its product by air.

“We’ve encountered low-level resistance because fresh sells, particularly in seafood,” Sims said. “Restaurants are not opposed to frozen fish. They are just more willing to pay a premium for fresh. ‘Fresh’ is the single most powerful adjective in describing seafood.”