Flickr: babaghan

by Hichem Omezzine

A recent publication by McAfee suggests that an estimated 62 trillion spam emails were sent worldwide in 2008.  The paper argues that this volume of spam requires an energy use of 33 billion kilo-watt hours which is equivalent to:

• The electricity used in 2.4million homes in the US
• GHG emissions of 3.1 million passenger cars
• Use of 2 billion US gallons of gasoline

A single spam email emission is associated to an average of 0.3 gram of carbon dioxide emissions. This means that worldwide spam email is equivalent to 18.6 billion kg of CO₂ emissions. That’s like driving around the earth 1.6 million times.

A more puzzling statistics is the fact that a fifth of a typical medium-size business email energy use is associated with spam emails. Until very recently spamming was very concentrated. The shutdown of web hosting firm McColo in late 2008 – accused of facilitating a major volume spam activity – is estimated to equate the take off 2.2 million cars of the road from an environmental perspective. The global spam volume dropped 70% overnight the day the firm was taken offline.

The MacAfee publication used an ICF International study which attributes the large share of spam’s GHG emissions to energy used in the process of processing and deleting a spam or searching for a legitimate email erroneously labeled as spam (“false positives”). The remaining share of GHG emissions is attributed to the process of creating the spam, internet, message storage… Manually viewing and deleting spam emails as well as searching for the so called “false positives” seems to be the major source of GHG emission associated with spam and uses almost 18 billion KWh or 52% of total spam-related energy use.

In terms of country activity, the US tops the league table with 3.8 billion kg of CO₂ emissions associated with spam. China and India come second and third with a respective total CO₂ emission spam of 2.8 and 1.3 billion kg. The study found that countries with better internet connectivity and therefore more email users tend to use more energy per email. It also suggests that countries with higher spam email proportion tend to consume more energy per email. The US is close to topping the list in terms of percent of email received that is spam.

Source: McAfee; ICF International