The Live Earth global pop concerts did achieve some positive influence on its goal of changing people's attitudes on climate change, according to the results of a survey.

However, several people interviewed for the "Live Earth - Was It Worth the Energy?" study questioned celebrities' real motivation for taking part in the July 7 event.

Conducted jointly by Lightspeed Research, the U.K.-based market research company, and Ethical Reputation Index, which specializes in tracking consumers' ethical opinions, the survey examined the views of 600 Americans in the 18 to 45-year-old demographic, plus 200 Britons and another 200 Australians of the same age group.

Of the U.S.-based consumers who watched Live Earth, the study states, 61% said the event would encourage them to go green and change their attitudes towards the environment.

Of those who watched in the United Kingdom, 36% of those questioned had a positive reaction. In Australia, 51% said they had been spurred to do something about the climate.

Of those who did not watch the concerts, a much smaller number of those questioned said Live Earth had a positive impact.

In the United States, only 17% of the survey's participants who did not watch believed the concerts would prompt them to do something about the climate. This compares with 6% in the United Kingdom, and 18% in Australia.

Seventy-five percent of the U.K. respondents who did not watch Live Earth said the event would not encourage them to do anything to protect the environment.

Most Live Earth cynics could be found in the United Kingdom, where only 40% felt climate change was the real motivation for the celebrities participating.

This compares with 52% of the U.S.-based respondents and 68% of Australian participants.

"It is interesting to see that the people who actively watched the event are now more likely to change their behavior," said David Day, Lightspeed Research's CEO, in a statement. "This suggests that global events such as Live Earth can have a positive influence, but it's still not clear if they are the most effective medium to reach the widest possible audience."

Of the skepticism shown by some of the respondents, The Ethical Reputation's Karen Fraser adds: "Perhaps artists and celebrities aren't seen as credible voices to encourage people to limit their environmental impact, or it may be that some of the coverage of the event detracted from the organizers' message."