How much energy does it take to shoot off a single tweet? Not that much, according to Raffi Krikorian. Earth2Tech tells us that the Twitter developer recently gave a talk at Chirp entitled "Energy/Tweet," where he claimed that a tweet consumes approximately 100 joules of energy (0.02 grams of CO2 emissions). That means Twitter's carbon footprint is relatively low--the 50 million tweets sent out daily emit one metric ton of CO2. In 2006, a single American family emitted an average of 24 metric tons of CO2 from home energy use and transportation combined.
Twitter's carbon footprint is also low compared to both Google searches and spam. A single Google query emits 0.2 grams of CO2, while a spam email emits 0.3 grams. There is one caveat to Krikorian's calculations, however--he only takes into account the CO2 produced by Twitter's infrastructure and ignores carbon dioxide generated by third party servers (i.e. Twitpic), the computers used to write the tweets, and the Internet processes used to distribute them.
Internet users aren't likely to stop tweeting, searching Google, or receiving spam messages any time soon. But there is one obvious thing we can do to lower the carbon footprint of our computer use: embrace renewable energy. The IT sector's energy use is poised to grow dramatically, with cloud computing projected to use 1,963.74 billion kilowatt hours of electricity by 2020. If we don't start adopting more solar, wind, hydroelectric, and geothermal energy, our appetite for all things electronic will get the better of the planet.