Teaser newspaper ads, billboards and T-shirts asking people to "save Miguel" are in fact a plea by the beleaguered Portuguese cork industry to persuade environmentally conscious consumers to choose cork over plastic stoppers or metal screw caps.

Next week the world's largest cork manufacturer, Amorim, will write to winemakers and retailers telling them why cork is the greener option.

The forests of Portugal, which produce most of the world's cork, offset nearly 5 million tonnes of carbon dioxide emissions each year. Producing a tonne of aluminium screw caps generates four times more greenhouse gases than a similar quantity of cork, according to industry analysis.

The ads will argue that if Australian consumers continue to choose caps over corks then the forests, along with 60,000 jobs and the rare flora and fauna that depend on them, will disappear. Seven out of every 10 bottles sold in Australia use screw caps, more than any other country.

Experts doubt drinkers will be convinced. By next June the production of Australia's most popular still wine, Wolf Blass, will move to screw caps. The chief winemaker at Foster's, Chris Hatcher, ruled out a return to cork. "There's absolutely no resistance by consumers [to screw caps] and really the argument for returning to cork is an emotional one," he said.

Winemakers also criticise cork producers for failing to eradicate cork taint, the mould found in corks that can spoil a wine. Rick Kinzbrunner of Giaconda winery said most bottle shop customers wanted screw caps because they did not want to risk cork taint.

Paul Bradbury, of Whybin TBWA/Tequila, the agency behind the campaign, said: "We'd lose if we were to mount a rational argument so the emotion that surrounds the environment plus the heritage of the industry is really all we've got."