Study States Spam Contributes to Global Warming

We knew that spam e-mails drained our time, resources, and productivity, but apparently spam is also contributing to global warming. Security-technology company, McAfee, and the technology-research company, ICF International, have just released a joint study that claims that the 62 trillion spam e-mails sent in 2008 generated approximately 33 terawatt hours (TWh) of energy per year.

To put that in perspective, the study states that is the "equivalent to the electricity used in 2.4 million homes in the United States, with the same GHG [greenhouse gas] emissions as 3.1 million passenger cars using two billion United States gallons of gasoline." ICF claims that this adds up to the equivalent of 17 million metric tons of CO2, which accounts for 0.2-percent of the global CO2 emissions.

The study calculated spam's estimated carbon footprint, by analyzing the energy consumption used in the different activities related to spam, which include:
  • Harvesting addresses
  • Creating spam campaigns
  • Sending spam from zombies and mail servers
  • Transmitting spam from sender to receiver via the Internet
  • Processing of spam by incoming mail servers
  • Storing messages
  • Viewing and deleting spam
  • Filtering spam and searching for false positives

Credit: McAfee

Even though these activities are evenly split between sending and receiving spam e-mails, the study estimates that the majority of the energy consumed related to spam activities--about 80-percent--"comes from end-users deleting spam and searching for legitimate email (false positives)." The ICF estimates that a "legitimate" e-mail generates the equivalent of 4 grams of CO2, while a spam message emits only about the equivalent of 0.3 grams of CO2. That might not seem like a lot--especially when you consider than a legitimate e-mail generates more than 13-times the equivalent of CO2 as spam. However, once you consider how much spam there is, it adds up very quickly:

"The average GHG emission associated with a single spam message is 0.3 grams of CO2. That's like driving three feet (one meter); but when multiplied by the yearly volume of spam, it is equivalent to driving around the earth 1.6 million times."

Credit: McAfee
When the McColo ISP was taken offline last November, this resulted in a 70-percent global drop in spam. ICF estimates that this amounted to the equivalent of "taking 2.2 million passenger vehicles off the road." Unfortunately, since then spam levels have started to rise again, and its estimated that quantity of spam has returned back to the levels we were seeing before the McColo ISP takedown.

Of course, even fighting spam consumes energy: "approximately 5.5 billion KWh annually or about 16 percent of overall spam energy use." The alterative, however, is much worse. In fact, the study estimates that current levels of spam filtering saves about 135TWh of energy per year; and it further states if "every inbox were protected by a state-of-the-art spam filter," roughly 75-percent of the energy consumed by spam could be reduced--"that's equivalent to taking 2.3 million cars off the road."