Why the Spam Carbon Footprint Study is Wrong

McAfee just released the details of a new study, conducted and published by ICF International, which seeks to measure the carbon footprint of spam. The study's conclusions: The global annual energy used to transmit, process, and filter spam is the equivalent to powering 2.4 million homes, and spam filtering saves 135 terawatt hours--the equivalent of taking 13 million cars off the road. The study decides that the average greenhouse gas emissions associated with an individual spam email are about 0.3 grams of CO2. Fascinating, right? But it's completely wrong.

There's one basic tenet of this study I take issue with, and it centers around the finding that most of the energy consumption associated with spam (nearly 80%) comes from end-users deleting spam and searching for legitimate email.

The study doesn't detail the methodology , but we can conclude that the real carbon footprint of a spam message lies in the energy wasted by PCs, notably the fixed amount of time users spend dealing with spam. The math sounds solid: Figure out the average power that a PC draws, the average amount of time spent dealing with each message, and the total volume, and calculate away.

But is that energy wasted really associated with spam? Do people turn on their PCs, read their email, and then turn them off? Or would their PCs simply be on anyway? If you had absolutely no spam in your inbox, would you turn your PC off earlier--or use the extra time you've saved to play more World of Warcraft? Business users leave their PCs on all day regardless of whether they've finished sorting their inboxes, so in my eyes you can't count any of the energy exhausted by their PCs. Besides, many email users don't have to deal with (much) spam anyhow, with filters on the job. (Well, my old Hotmail account gets hundreds of spam mails a day, but really, I only have to deal with them when the computer is supposed to be on anyway).

In my eyes, you could really substitute "Bejeweled" or email in general or any other computing activity for spam and reach a similar computing, if all we're doing is quantifying uptime. Bottom line: PCs waste energy, and humans leave them on too long, wasting energy. But spam? It's kind of meaningless here.