MIAMI — Global warming may be bad for the environment, but it has been great for one industry: eco-marketing.

With April being the month we observe Earth Day, it seems every industry is eager to tout its green credentials. There are environmentally friendly spas, green printing presses, green liquor companies and green alternatives to inflating the tires of your gas-guzzling sport-utility vehicle.

There are at least two good reasons for the green push: the environment, of course, and greenbacks.

According to the LOHAS Journal, which measures the green marketplace, 19 percent of U.S. consumers buy goods with an eye on their sustainability and environmental impact. Green products generate about $227 billion in sales, and that could reach $1 trillion annually within 12 years, the journal estimates.

"Every major player in every industry is trying to figure out an environmental strategy," said Marci Zaroff, the founder of Under The Canopy, a Boca Raton, Fla.-based manufacturer of certified organic clothing available at more than 300 outlets, including Target and Macy's. "It's not about keeping up; it's about not being left behind."

For Shorne "Q" Fortune, going green is about getting ahead of the competition. Last year, Fortune and his wife, Grerimar, changed the name of their Miami scooter company from VIP Vespa to Grow Verde to reflect their new take on business.

Rather than focus on the glamour and convenience of zipping around South Beach on Vespa scooters, they are recasting the company as an eco-friendly alternative to renting or owning a car.

Verde (Spanish for green) now works on a membership basis, a bit like ride-sharing pioneer Zip Cars.

Fortune says personal conviction and client demand are fueling the change. "We talked to our customers, and they wanted some sort of service they could use where they didn't feel guilty," he said. "We all have to do our part to reduce our carbon footprint."

The company will be making its formal launch in June, but the change is already making a difference. "It has been getting us a lot of attention," Fortune said. And getting noticed is half the battle.

But with everyone from Kmart to Clorox rushing into the green marketplace, some worry that consumer confidence in the emerging niche might be trampled.

In 2007, environmental marketing company TerraChoice studied 1,018 products that made environmental claims. It found all but one of the items made statements that were either demonstrably false or misleading.

The TerraChoice study may have suffered due to overly stringent standards — everything from outright lies to vague wording sent up red flags — but it does illustrate problems in the green marketplace, said Joel Makower, the executive editor of GreenBiz.com, an online publication that follows environmental business trends.

While there are standards for energy-efficient appliances and green construction methods, "there is no clear definition for what makes a green business," he said. The category can include everyone from the corner shop selling hemp socks to the industrial dry cleaner investing in energy-efficient machines. "That makes it a bit of the Wild West out there," Makower said.

Nature and commerce abhor a vacuum, and more than 140 organizations have stepped in to try to formulate guidelines for running a green business — but there is no consensus, Makower said.

Zaroff, of Under the Canopy, started her firm in 1996 when the organic clothing industry was more about "hippie than hip."

Since then, she has seen sales soar 50 percent to 100 percent annually into the "double-digit millions" as the niche has gone mainstream.

But Zaroff worries that newcomers, drawn by profits more than environmental conviction, might not be as careful about vetting their suppliers.

"Consumers need to be aware and beware," she said. There are companies in her industry, she said, making environmental claims they probably cannot support. "There are some investigations starting, and people will get caught with their pants down," she predicted.

But going green has its costs.

Ana Rabel and her daughter Laura Alfonso pay almost three times as much for the eco-friendly products they use at the Green Gables Cafe, the organic eatery they opened six months ago in Coral Gables.

Their cups are made of biodegradable cornstarch, the napkins are made from unbleached recycled paper.

"We don't use plastic at all — but let me tell you it can be expensive to be responsible," said Rabel.

"If it means making a little less money right now until people are educated, and I can add those costs into the price of my food, then that's what we have to do," she said. "It's the only responsible choice."