How can I persuade cellphone users sitting in their cars to stop pumping out all those unnecessary greenhouse gases? I'm glad these people aren't texting/talking/swiping while driving, but shouldn't they turn off their engines, too? —CO2 & You

Cellphones already come with one highly effective CO2-mitigation strategy: causing fatal car accidents. This neutralizes the carbon footprints of people who otherwise would have continued—in some cases, for decades—such carbon-intensive activities as driving; taking long, hot showers; and exhaling.

Of course, there's always some do-gooder to come along and talk during the Grim Reaper's backswing, so hands-free laws and "don't text and drive" campaigns have slowed the carnage.

In fact, a bill currently working its way through the Oregon Legislature (House Bill 2597) would broaden the prohibition against texting or talking while driving to include pretty much anything you might do with a phone (or similar device) in the car.

This means no more tweeting, swiping, Instagramming, Candy Crushing, or doing that thing where you turn on LinkedIn notifications, set your phone to vibrate, and stuff it down your pants.

Such social opprobrium may eventually begin to penetrate the skulls of phone-mad drivers. Soon, instead of veering into the oncoming lane while retweeting pictures of Taylor Swift with Hitler quotes, social-media addicts may pull over and retweet the same pictures while pointlessly burning half a tank of gas. We will call this "progress."

Which brings us to your question, CO2. So far, we haven't seen an environmental study of cellphone-related engine idling. Anecdotal evidence is pretty overwhelming that the activity is on the rise, however—and you're right to object.

Some folks think turning your car off and on causes more pollution than letting it idle. They're wrong: If you're going to be stopped for more than 10 seconds, you should turn off the engine.

To persuade people, just try to get that info out into the world. Could you write in to a newspaper column or something? Try to pick one in which the guy doesn't sound like a serial killer.

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