What's the carbon footprint of email spam?

Dastardly spam! It's a nuisance, potentially fraudulent, could infect your computer – and has a hefty carbon footprint.

As the world filters out spam from its collective inboxes, and retrieves false positives from email junk bins, it wastes enough energy each year to power 2.4 million American homes and indirectly releases the same amount of greenhouse gas as cars burning two billion gallons of gasoline.

These statistics come from "The Carbon Footprint of Email Spam Report" compiled by eco-consultants ICF and commissioned by computer-security firm McAfee.

A single spam message produces the equivalent of 0.3 grams of CO2, the same as driving three feet in a car. Multiply that by 62 trillion pieces of spam circling the globe each year, and you have the emissions equivalent of driving around the Earth 1.6 million times.

Eighty percent of this energy goes toward individuals cleaning out their inboxes. As they sift through junk mail, their computers and monitors keep sucking up power. Spam filters, on the other hand, only account for 16 percent of the energy total. The report concludes that if everyone used effective email filtering (such as McAfee's software – nudge, nudge) it could "reduce today’s spam energy by approximately 75 percent.... That’s equivalent to taking 2.3 million cars off the road."

An even better way to clamp down on wasted power would be cutting off the source. When big-time spammer McColo was shut down last year, the energy saved "equated to taking 2.2 million cars off the road." And that was only one spam ring.