The biggest problem with the new Green-fad is its focus on carbon footprint. First of all, there are lots of metrics to measure the environmental impact of a product or an activity. Looking only at carbon misses other important issues like sustainable materials, toxic manufacturing processes, and local social and ecosystems. Even more than that, though, is the fact that everything we do has a carbon footprint, so talking about the footprint of any one thing is meaningless without a relative comparison.

Driving to the store releases a given amount of carbon, but so does walking. The average person contributes about 800g of carbon to the atmosphere each day just by walking around. Go for a run and you're hurting the environment. Don't go for a run and you get fat. Obesity is linked to a whole variety of diet-related chronic diseases, so you'll be visiting the doctor more often. Hopefully they're close, so you can walk. If you can't walk, then maybe you don't go, so eventually you die. Personally, I want to be cremated, but I bet that incinerator puts out some serious CO2. Burial? Gotta dig a hole (lots of breathing there). Shit. Maybe I should just go running.

So, here's Alex Wissner-Gross, the smart-as-hell physicist of the hour who chooses to delve into other issues, estimating that each Google search releases 5g of carbon. News flash, Alex. Being smart at one thing doesn't necessarily make you smart at other things.

I can't speak to how correct the estimate is – I'm sure Alex is very good with numbers. And I'm sure Google will come out right away and say he's wrong. The point is, 5g for a Google search is meaningless. The only question is whether 5g is more or less than our alternative. I wouldn't be surprised at all if Google, Yahoo!, MS, Ask all start competing for the title of the world's greenest search engine. In fact, I'm going to go ahead and predict that this very thing will happen in 2009, further distracting people from real environmental problems, real environmentally-friendly decisions.