Americans are the the least likely to suffer from "green guilt" about their environmental impact, despite trailing the rest of the world in sustainable behavior, according to a new National Geographic survey.

This year's Greendex report, conducted by the National Geographic Society and the research consultancy GlobeScan, also found that Americans are the most confident that their individual actions can help the environment. (National Geographic News is a division of the Society.)

"There's a disconnect there, and we hope the Greendex helps shed light on it," said Eric Whan, GlobeScan's director of sustainability.

"In our culture of consumption, we've sort of been indoctrinated to believe that we can buy ourselves out of environmental problems," said Whan, who's based in Toronto, Canada, another country ranked low in the survey.

"But what people need to realize is that the sheer volume of consumption is relevant as well." (Listen to NPR's coverage of Greendex.)

Conducted by the National Geographic Society and GlobeScan since 2008, the Greendex report explored environmental attitudes and behaviors among 17,000 consumers in 17 countries through an online survey that asks questions relating to housing, transportation, food, and consumer goods. (Learn more about how Greendex is created.)

This year Americans ranked last in sustainable behavior, as they have every year since 2008. Just 21 percent of Americans reported feeling guilty about the impact they have on the environment, among the lowest of those surveyed.

Yet they had the most faith in an individual's ability to protect the environment, at 47 percent.

Consumers in India, China, and Brazil led the pack, with Greendex scores in the high fifties. Paradoxically, many Indians, Chinese, and Brazilians reported feeling the most guilt about their environmental impact and had the least confidence that their individual actions can help the environment.

Green Guilt

Taken together, the findings suggest that those with the lightest environmental footprint are also the most likely to feel both guilty and disempowered, Whan said.

"Despite their relatively light footprints as consumers, there seems to have been some internalization and a sensitization to environmental issues in places like China, India, and Brazil," he added.

"There's a more widespread sense that environmental issues are affecting people's health in those countries. Concern is higher about things like water and air pollution, and there's also a real sensitivity to global warming."

Nicole Darnall, a researcher at the School of Sustainability at Arizona State University (ASU), called the association between guilt and Greendex scores "intriguing."

"In order to feel guilty, you have to accept that some sort of problem exists," said Darnall, who was not involved in the survey.

"And in looking at the countries that don't feel guilty, they're the ones that I would suggest are not necessarily accepting that a problem exists. These are countries in which there's still a lot of political debate about whether certain problems"—such as climate change—"exist or not."

Moving Forward

Americans also ranked last in the area of transportation. According to the Greendex report, Americans were the most likely to report regularly driving alone in a car or truck (56 percent) and the least likely to use public transportation (7 percent).

They were also the least likely to bike or walk to their destination, while Chinese consumers were the most likely to do so.

This could just be a reflection of the fewer number of people who own cars in the country, GlobeScan's Whan noted, and China's Greendex transportation score could decrease as the use of cars in the country rises.

ASU's Darnall noted that China, and other countries where cycling rates are high, have cultures that are more accepting of bikes on the road in the first place.

"In Phoenix and most other U.S. cities, you're often taking your life in your own hands when you get on a bicycle," she said.

(Learn more about sustainable travel and transportation on National Geographic's Green Guide.)

What's Really Green?

One area where Americans scored well was in the area of purchased goods, with U.S. respondents (31 percent) saying that they prefer to buy "used" or "pre-owned" products over new ones.

Americans are also above average when it comes to recycling (69 percent) but are surpassed by Canadian, British, German, and Australian consumers. Despite ranking second in the subcategory relating to consumption of goods, South Koreans are the least likely (29 percent) to recycle, according to the survey.

One common trend revealed by the survey is that many consumers find it difficult to justify the price premium often associated with environmentally friendly products. Russians, Brazilians, Americans, and Indians were the most likely to respond that the extra cost does not justify the value.

Part of the problem is that in the U.S. and many countries, there is a lack of good information and trusted sources regarding green products that consumers can turn to, said Thomas Dean, of Colorado State University's College of Business, who did not participate in the survey.

ASU's Darnall agreed. "How do we know that one product is greener than another? Right now, in our current marketplace, we can't," Darnall said. "This is one area where the government can step in and play a stronger leadership role."

Dean thinks setting up a third-party certification system for green products like the one that exists for organic foods would be helpful.

"In the United States we know a food is organic because there's a certification process in place that is set out by the U.S. Department of Agriculture to define what organic foods are," he said.

"And that results in a label that is considered legitimate by consumers."

Green Eating

On the topic of food, more than half of all consumers in almost all the countries surveyed reported eating beef—one of the most environmentally intensive food sources—once or more per week. Argentines reported eating the most beef (61 percent), as opposed to 35 percent of Americans and 9 percent of Indians.

Chinese consumers eat the most vegetables: 63 percent eat them every day, versus just 37 percent of Americans.

Other interesting food findings: Germans are the biggest consumers of bottled water, with two-thirds reporting that they drink it daily. And Spaniards are now the biggest consumers of seafood, while the Japanese are eating less—probably a consequence of the 2011 tsunami and Fukushima nuclear power plant disaster, Whan said. (See "One Year After Fukushima, Japan Faces Shortages of Energy, Trust.")

"There's some evidence of some fisheries being closed in [Japan] because of radioactive contamination," he added. "We also know that the capacity of the fishing fleet was severely affected [by the tsunami]."

Green Self-Delusion?

One puzzling and potentially worrisome trend observed among respondents in all of the countries surveyed was that consumers tended to report being greener than they actually may be.

When asked what proportion of their fellow citizens were green, most people responded 20 to 40 percent. Yet when asked if they themselves were green, more than half said they are.

This might be a form of green self-delusion on the part of consumers, but it might also be due to a well-known effect in sociology called the social desirability bias, in which respondents often say what is socially desirable than stating their true feelings and actions, said Darnall.

"It's not a surprise that consumers believed they were environmentally responsible," she said. "Consumers want to respond in a socially desirable way, and there is a lot of research that suggests they're not going to respond very honestly about their less socially acceptable behaviors."

GlobeScan's Whan said he hopes the Greendex survey will make people take a closer look at their own consumption patterns and their effects on the environment.