Whether you follow a vegan diet or are a devoted carnivore, carry canvas or plastic, you are one of 7.5 billion people. The ecological effect of your choices is minuscule. And yet they have a big effect on how others see you, and how you see yourself. Psychologists found that prodding people to worry about social status increased their interest in buying green versus nongreen items—but only if they were shopping in public.  People in Washington State and Colorado were willing to pay a premium of $430 to $4,200 (results varied by zip code) for the green-signaling Prius over an equally efficient car that didn’t broadcast its virtue. 
Surveys of tens of thousands of British people suggest that green behaviors such as buying recycled products and taking public transit increased life satisfaction—but only insofar as they made people feel green. And feelings can be misleading: Most people who called themselves green never carpooled or avoided flying. 
Self-congratulation, moreover, can lead to self-indulgence. When people shopped in a green (versus conventional) simulated online store, they felt like they’d done their good deed for the day and were more likely to cheat or steal in a subsequent task—an effect psychologists call “moral licensing.”  Similarly, getting weekly feedback on water consumption reduced people’s water use by 6 percent, but it increased their electricity use by 5.6 percent—as if they felt that being careful in one area entitled them to relax in another.