In June, a two-minute video ad commissioned by the restaurant chain Chipotle won a grand prix award at the Cannes Film Festival in an advertising category. The ad depicts a farmer who first turns his land into a polluting factory farm before opting for a sustainable model of agriculture that produces the ingredients used in Chipotle's food. The success of this ad underscores that advertising about environmental issues can strike a chord in many viewers. However, a recent study found that these ads are most common when the economy is doing well.

Three researchers at Penn State University recently examined 30 years' worth of environmental advertising and found the the gross domestic product of an era correlates to the level of green advertising produced.

"We found that changes in the GDP do indeed predict the level of 'green' advertising," said Lee Ahern, assistant professor in the Department of Advertising/Public Relations at the university.

Although many advertising executives have theorized a relationship between economic well being and environmental awareness and concern, this study is one of the first to provide clear evidence that this relationship exists.

As America continues to pull out of the recession, adding a bit more "green" to a campaign may produce positive results.