I’m a big fan of Lewis Black, the perpetually befuddled-and-enraged comic who frequently appears on The Daily Show. This column is about something that makes me act just like him.

Last August, Carfax, the company that issues reports on the condition of used cars, sponsored a short-track NASCAR race at the Michigan International Speedway, and declared the day to be carbon-neutral.

Here’s how it works. Carfax calculated the carbon footprint at a typical race at about 4,200 tons of carbon entering the atmosphere from stock cars, fans traveling to the race, operation of the track, and ancillary things ranging from parking lot tailgate cookouts to cartons of Marlboros smoked. They worked with the Conservation Fund and carbonfund.org to fund the planting of enough trees to theoretically absorb that amount of carbon.

There’s a baseline number for this: An average size tree living an average lifespan of about forty years will absorb one ton of carbon over its life. A dense forest, with trees planted eight feet apart, has about 700 trees per acre. Others are more pessimistic: The Global ReLeaf project says three trees are needed to offset a single ton of carbon, since most trees don’t make it to age forty. But let’s go with the more optimistic number. 4,200 new trees equals one Saturday at the Speedway.

So the cost of offsetting one Saturday of NASCAR’s activities is about six acres of planted trees. At that rate, for one race a year, you could re-forest an area the size of the 1,400-acre Michigan International Speedway parking lot and track in just 233 years.

Let’s say NASCAR decided to go whole-hog on this carbon offset thing, instead of just one race a year. Its premier event, the Sprint Series, runs for 36 weekends at tracks around the country. Generally, the Sprint races are on Sundays, and a shorter race happens the day before. That’s 72 races times six acres of new trees each year which equals 432 acres a year. 

Of course, the carbon footprint of everything in the U.S. is a bit bigger: About 6 billion metric tons of CO2 per year. Let’s say we want to offset 10% of that, about 660 million tons of CO2. 660 million tons of CO2 contains about 180 million tons of carbon. At a ton per tree, that’s a net gain of 180 million trees per year (minus the ones that die, burn, or are cut down every year), or a net gain about 258,000 acres of new tree planting per year, just to offset 10% of the U.S. total. And then do it again every year. Roughly double those numbers if you want to add in China’s carbon footprint, and double them again to cover the whole world’s carbon impact, so it would be just over a million net acres of new trees per year to offset 10% of the world’s carbon. (Note to Lewis Black fans: This is where he’d grab his head and start to shake.)

So, in a world that’s in the midst of losing a horrendous amount of forest cover in the Amazon, Indonesia, Africa, and elsewhere (a recent estimate from the U.N. Food and Agricultural Organization pegged the recent global net loss at 19.7 million acres of forest per year), we can offset 10% of our carbon load by completely reversing our current trend: Instead of our current habit of losing what amounts to a bit less than a South Carolina-sized patch of tree cover in the world each year, we need to add a Delaware-sized patch of new trees each year. And weed and water vigorously.

Please don’t misunderstand me: Thinking about carbon offsets is a good thing, and so is calculating our individual carbon impact. NASCAR and one of its sponsors taking even one race a year to acknowledge that we have a little climate problem going on is a good thing, or at least certainly a well-intentioned thing.

The part of this that troubles me is that gestures like this one, often born in the marketing department, help create the illusion that an out-of-control problem is under control. It also goes a long way toward assuaging our guilt, and allowing us to continue with business as usual, even when business as usual is a potentially deadly thing. Homer Simpson does this when he rationalizes that since his Duff Lite Beer has two-thirds the calories, he’s okay to drink three times as many. The Catholic Church, from which I retired many years ago, used to do this by selling papal indulgences to the real-life equivalents of Michael Corleone: Write a check, and absolve your sins.

Let’s not do away with carbon offsets, but let’s not use them to absolve our own guilt. Empty carbon-neutral claims may turn out to be the environmental movement’s equivalent of the American flag lapel pin: We like to show how much we care, without really changing our values or behavior.

The tree-planting thing is undeniably a good thing. Last week, a study published in the journal Nature reported that trees suck up about one-fifth of the CO2 we deposit into the atmosphere. But it’s a good thing that, by itself, could be an empty, inadequate gesture.

So if you’re packing up the R.V. to head out to next year’s carbon-neutral NASCAR race, here’s a suggestion to make you feel good about the environment: Stay home. And plant a couple of trees. You’ll actually come out ahead.

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Peter Dykstra, the former executive producer of CNN's Science, Tech and Weather Unit is currently a Public Policy Scholar at the Woodrow Wilson Center in Washington. He writes three columns for MNN: Media Mayhem on Mondays, Political Habitat on Wednesdays, and Green States on Fridays. (Yes, he writes a lot.)