Estimating your carbon footprint with a cell phone is sort of like testing your cholesterol with a cupcake. After all, due to carrier contracts, even perfectly functional cell phones are practically preprogrammed to self-destruct after two years, needlessly restarting the energy chain (mining of raw materials, manufacturing, shipping, etc.). Cell phones are among the most nonrenewable of our resources — and all before the billions of little power suckers are ever plugged in.
At least the 20 million-plus iPhone owners worldwide have one measure of recourse: a multitude of carbon-footprint rulers at their fingertips. They're some of the Apple App Store's 60,000-plus downloadable applications for the iPhone, whose green selections — everything from locating nearby recycling drop-offs (iRecycle) to discerning what's in a household product (GoodGuide) — are growing faster than digital trees (see: iPhorest, which for $4.99 allows you to have an actual sapling planted along the Gulf Coast and interact with its on-screen avatar). The best of the footprint-measurement bunch is Carbon Calc, a free program that collates your air and automotive travel with regular home energy usage, and even allows you to purchase offsetting carbon credits with a PayPal account. It's a handy-dandy karmic rebate, conveniently made available on a device reportedly responsible for somewhere close to "the same emissions you'd make by taking a return flight to Cancun from Alabama on a Boeing 737" (www.trade2save.com). — Noah Bonaparte Pais