IT accounts for a shocking 2% of worldwide carbon emissions – that’s the same as aviation. While your desktop might be relatively frugal, it’s just the tip of the slowly-melting iceberg. Right now I’m using GMail, Bloglines, my work email, a forum which lives on a server in London and Slashdot – I’m using power all over the world. Take into account all the networking gear sitting in the middle, and the true energy usage of my PC could be astronomical.

Maybe we need to start thinking about our carbon netprint (it seems like as good a phrase as any) when we look at our carbon footprint; do you really need that Facebook, MySpace or Bebo account? It’s not just actively using these services that consumes power; a MySpace account sitting idle, not accessed for months, still requires power to store – and more than you may think.

Speaking yesterday at the Green IT conference in London, Graham Perkins of Sybase gave this scenario; imagine a company has to keep 3 Petabytes of data for some reason; legal compliance, he suggested, as “everyone’s being expected to hold onto it for much longer than before”.

In an average setup, claims Perkins, this will take up 118 disk cabinets. Take into account the running costs in energy, as well as cooling, and you get the somewhat shocking figure of £2.5 million per year, and 25,000 tonnes of CO2 released into the atmosphere. That’s before you’ve accessed, modified or processed that information – just from sitting there.

Imagine, then, that this data is something as trivial as the combined “favourite bands” of millions upon millions of inactive social networking accounts. Quite a waste.

It’s only a matter of time before the wider public realises this, and when that happens, the same sort of public scrutiny will fall on the IT industry as has done on long-haul flights, 4×4s and gadgets-on-standby for years. Having a huge carbon netprint could be as unfashionable and unacceptable as driving an inefficient car.