How much does a character typed on an e-mail contribute to global warming? Until recently, I had taken it for granted that electronic communications were "clean", with zero impact on the environment. I started having second thoughts when I read 1.5% of the world's electric supply is consumed by server farms (and growing at a fairly substantial rate).
Rather than go on faith alone, I figured I'd do the math... Before we go on, here are the disclaimers on my analysis: (a) it is based on the top results of my Google searches, (b) the math was not double-checked, (c) sources were not scrubbed for reliability and (d) they are not cited. Therefore, (e) these findings should be interpreted as directional.
If we consider there are approximately 150 billion e-mails being sent every day and the average number of words per e-mail is about 110 -with an average word length (in the English language) of 5.1 characters, then we have approximately 30 quadrillion (15 zeroes) characters being e-mailed per year.
I could not get a more recent figure (I'm sure it's out there), however in 2005, the worldwide energy consumption was 500 exa-Joules (EJ --18 zeroes), 86% of which was created by burning fossil fuels. If we go back to 1.5% of this supply being used by server farms, that leaves 7.5 EJ (6.5 EJ from fossil fuels). Keep in mind that only about 1.5% of internet traffic is actually e-mail, which leaves 100 peta-Joules (15 zeroes) of carbon-emitting electricity used for e-mail.
If you divide these two figures out (total characters e-mailed and fossil-fuel-based energy used to power them), you get 3.17 Joules of electricity per-character e-mailed. Fossil fuels emit between 60 (natural gas) and 90 (coal) kilograms of CO2 per giga-Joule (9 zeroes). If we use the average of 75 Kilograms (165 pounds), we get 0.0000005 lbs of CO2 for every character you type and send on an e-mail. That means that with 2,625 characters in this e-mail (including spaces), 0.0012 lbs of CO2 were emitted per recipient. With 60 recipients, this e-mail may be responsible for an astounding 1/12 of a pound of CO2 (if these calculations hold). Now before you start driving places instead of sending e-mails, you should know a gallon of gas produces 19.4 pounds of CO2 as it gets burned in your car.
Fortunately, walking over to my desk to grab a donut does not require you burn any fossil fuels and Rich Law's donut selection ensures your trip is highly likely to be worthwhile. So, come on down and grab a bite (in-fact, a giga-bite may be in good order today), besides, the walk should help build some... character.