British environmental group Global Action Plan has released a study [pdf] of the carbon footprint of the British IT industry. They argue that "servers are at least as great a threat to the climate as SUVs or the global aviation industry:"
"Computers are seen as quite benign things sitting on your desk," says Trewin Restorick, director of the group. "But, for instance, in our charity we have one server. That server has same carbon footprint as your average SUV doing 15 miles to the gallon. Yet, whereas the SUV is seen as a villain from the environmental perspective, the server is not."
The report, An Inefficient Truth [actually, "The Inefficient Truth"-- ed.] states that with more than 1 billion computers on the planet, the global IT sector is responsible for about 2% of human carbon dioxide emissions each year – a similar figure to the global airline industry.
Also - from Smartmobs - how 'A web-based service carbonhero.net uses GPS phones to track the modes of travel and deduce carbon emissions of the phone owner, then transmits the carbon footprint to the device’s owner'