This article was originally published on ComputerWeekly.com

The 62 trillion spam emails sent in 2008 created carbon emissions equivalent to that of 2 billion gallons of petrol burnt in a car engine, according to a report (pdf) by computer security firm McAfee.

The report looked at the energy expended to create, store, view and filter spam on personal computers and servers across 11 countries, including Australia, China, France, the US and the UK. It found that the level of spam-related emissions generated in these countries is proportionate to its number of email users and the percentage of email that is spam, making it possible to estimate the total energy used by spam worldwide.

Nearly 80 per cent of the energy used by spam comes from end-users deleting it from their inboxes and hunting for legitimate email. While spam filtering software takes up a further 16 per cent, it also reduces the overall energy impact of unsolicited email.


The annual energy used to transmit, process and filter spam totals 33 billion kilowatt-hours, the report concludes, which is equivalent to driving around the Earth 1.6 million times or the energy usage of more than 2 million typical homes.

“Stopping spam at its source, as well investing in filtering technology, will save time and money, and will pay dividends to the planet by reducing carbon emissions as well,” said Jeff Green, senior vice president of product development at McAfee.

As computer use continues to grow, scrutiny on the energy use of the servers that power everything from the internet to banking services is increasing. Last year, researchers at the University of California, Berkeley, and chipmaker Intel showed that delaying the flow of network data by just a few milliseconds can cut power consumption of some hardware by 50 per cent.