Some people save energy because they care about the environment; others want a reward for doing so. That’s okay, according to Marcia McNutt, president of the National Academy of Sciences and former editor-in-chief of the journal Science. At Stanford University’s annual Connecting the Dots symposium, McNutt told participants that to promote good environmental behavior, they must tailor their messages for different audiences.

Some people “always want to do the right thing, and all you have to do is get them the right information,” even if it is complicated, she said. “Others want to try to do the right thing, but the information might be really, really complicated. So, if you want them to do the right thing, you’ve got to make it really easy for them.”

In fact, McNutt said, the right actions can be counterintuitive, situational, or even ephemeral. To illustrate her point, she asked the audience: What is better for the environment—driving a diesel-fueled Volkswagen or an electric Tesla?

In California, where most of the conference participants live, electric vehicles are better, but that is not true in most of the United States, she said. States east of the Rocky Mountains, except Texas, still generate enough electricity from coal-fired power plants that electric cars do more ecological damage than diesel motors.