If you’re not green, you may soon be red-faced.

There are a variety of sources of behavioral influence that guide action and decision-making. These sources generally fall into three spheres: personal, social and structural. In some of our past Shelton Pulse studies, we’ve spent a great deal of time examining the personal sphere of influence by determining our respondents’ self-concept, worldviews and motivation. In this year’s Green Living Pulse, we’ve turned our attention to the social sphere of influence, or how those around us influence our behavior.

We learned that acting in an unsustainable way isn’t very embarrassing yet, but it will soon reach the tipping point. Thanks to years of growth, messaging and new products, the idea of sustainability has finally permeated the American conscience. Not only are they searching for and buying more green products than ever, but more than half of Americans are beginning to define sustainable behaviors as the socially accepted norm.

Granted, being caught with your thermostat set at 73 degrees isn’t as embarrassing as getting a citation for drunk driving – yet. But if you apply the Tipping Point rule postulated by author Malcolm Gladwell, which says that ideas grow explosively once 20% of the population adopts them, then our data clearly show that acting in ways that aren’t eco-friendly will soon be considered embarrassing for greater numbers of people.

This is important because sustainability will no longer be considered a fringe activity limited to a small group of hard-core activists or early adopters. Any lingering stigma around being green will continue to fade as it becomes more socially acceptable to larger and larger chunks of the mainstream population. Sustainable habits will be spread through social contagion because there are simply more idea carriers now. This trend also signals that sustainability has become a true habit for many consumers – and a critical part of some people’s self-image. It means that some people are holding themselves accountable for their own sustainable actions because failing to act in accordance with their values would violate their self-concept.

To see what’s next, we look to other large-scale social issues, such as the decades-long anti-smoking campaign. Once considered a mark of “coolness,” smoking has dwindled in popularity: fewer than 20% of American adults are now smokers, down from 37% in 1970. Smoking is generally considered to be socially unacceptable thanks to years of messaging, public bans and social contagion. As more people quit smoking, they also influenced people up to three degrees of separation to quit. Now you see small bands of smokers gathering in distant corners of parking lots, unwelcome in their building, perhaps even in violation of their company’s policy.

Will this be the reality for sustainability one day? If the trend continues, we can certainly see that it’s a distinct possibility. Maybe one day we’ll all be saying, “If you’re not green, you’re not cool.”