Your Mileage May Vary
Your car's greenhouse gas emissions are about 25 percent worse than you think.
How so? Well, for each gallon of gas you burn in your engine, there's the climate equivalent of another quarter-gallon or so embedded in your consumption. What that means is this: the gasoline you use didn't just magically appear in your tank -- it was extracted, refined, and transported to your local station. And all that activity released emissions.
It's a curiosity of our energy system (and other systems too, such as our food system), but it's a curiosity that bears closely on our thinking about how to reduce greenhouse gas emissions. Bear with me for a moment.
It's usually assumed that each gallon of gas releases about 19.5 pounds of CO-2 into the sky. (Some quibble, and argue that it's 19.4 or 19.6. But whatever.) Basic physics dictates that a gallon of gasoline combusted will release a more-or-less fixed amount of CO-2. But from a public policy perspective, physics isn't the whole story.
