National Geographic, the broadcaster, and GlobeScan, the research group, polled 17,000 people in 17 countries, and found that uptake of eco-friendly behaviour had increased in just five nations since 2010, and had decreased in nine.
India posted the highest national score on the index, of 58.9 points, when it came to choosing environmentally responsible options in the areas of food, housing and transportation, as well as upon making purchases. This reading, however, had fallen from 62.6 points last year.
Second position went to China on 57.8 points, ahead of Brazil in third on 55.5 points. Hungary was fourth on 54.4 points, level with South Korea. The US, by contrast, only recorded 44.7 points, behind Canada's 47.9 points and Japan's 48.5 points.
More specifically, the study analysed the ecological standing of shoppers when deciding whether to buy goods, like repairing rather than replacing something that breaks or acquiring used items instead of new ones.
India again led the charts on 57.3 points, trailed by South Korea on 57.1 points, China on 56.8 points and Mexico on 54.5 points. Brazil was next on 53.8 points, followed by Japan on 52.7 points.
The US occupied last place in the table on 44.2 points, with Canada and Australia on on 45.7 points apiece, France on 45.9 points and Sweden on 46.1 points.
"In most countries, minorities of consumers say that environmentally friendly product premiums are generally worth it to them, but many are undecided on this," the study added. "In descending order, Russians, Brazilians, Americans and Indians are the most likely to respond that the extra cost does not justify the value."
However, there was a substantial gap between the number of interviewees perceiving themselves as being "green", on 56%, and those which met the criteria required to earn such a status, on 34%.
The difference peaked in Mexico, where these totals hit 73% and 32% in turn. A majority of shoppers in 13 other nations thought they were environmentally sound, but actual ratings in these markets failed to top 40%.
South Korea registered the most accurate ratings on this metric, with 32% of contributors believing they had adopted good practices, only two percentage points short of the official figure.
When asked to select the words associated with green consumers, the terms "responsible", "caring", "healthy" "innovative" and "smart" proved prominent. But more negative words like "weird" "annoying" and "self-obsessed" were also commonly-cited.
Data sourced from National Geographic; additional content by Warc staff