Internet security firm McAfee reports that the 62 trillion junk e-mails sent in 2008 gobbled up enough electricity to power more than 2.4 million homes for a year.

In a study released yesterday, McAfee says that each unsolicited piece of spampromising you better performance in the sack or begging you to steward the riches of a foreign businessperson, for example – actually contributes 0.3 gram of the carbon dioxide (CO2) equivalent of greenhouse gas emissions to the atmosphere of an already-warming planet. The company and consultant partner ICF International reviewed emissions they pegged to spam in 11 countries and averaged those out for the rest of the world.

Although the methodology used is not clear, the companies say they arrived at these figures by determining the amount of time people spend cursorily reading and deleting plus retrieving genuine mail discarded as spam. McAfee and ICF International then looked at the energy consumption of computers and calculated the total amount of electricity needed to fuel this wasted time. In total, this personal sifting accounted for 80 percent of spam’s carbon footprint.

Critics including PC Magazine have denounced this aspect of the findings as “completely wrong,” however. The argument goes that if people are already using their computers to check e-mail, read online, play games, instant message, Twitter, surf for porn, what have you (point being: we spend a lot of time in front of a computer), then even if some additional minutes were not spent hacking away at spam, we’d be on the computer anyway. Also, if computers are simply left on all the time, at offices, for instance, then it hardly matters what a user spends his or her time doing as the computer is draining power 24/7 regardless.

In addition to this time and energy suck, spam also eats electricity by making computers do more work, according to the BBC. "The PC on our desks uses more power when they do work, so the numbers are based on the additional work they use when dealing with spam," Richi Jennings, a spam analyst involved with the report, told the British news outlet.

Mind you, McAfee has a vested interest in talking up the potential enviro-evil of junk e-mails: The company sells a spam-blocker/filterer called SpamKiller. McAfee isn't the only company to make a marketing appeal to eco-conscious consumers by touting greenness – and it unabashedly engages in some self-promotion in its report, informing readers that “if every inbox were protected by a state-of-the-art spam filter, organizations and individuals could reduce today’s spam energy by approximately 75 percent or 25 TWh (terawatt-hours) per year. That’s equivalent to taking 2.3 million cars off the road.” [italics by McAfee]

To see the full report, Internet users have to sign up at McAfee’s web site – here’s hoping that does not turn into another conduit for getting even more spam delivered to inboxes.

Image credit: California Bar Journal