How much computing can mankind afford? That is a question the computer and telecoms industries hate to hear. They do not see themselves in the same dirty league as airlines or carmakers, sources of huge amounts of carbon dioxide, but instead as part of the solution. In a pre-emptive strike, a group of technology firms calling itself the Global eSustainability Initiative (GeSI) has joined the Climate Group, a non-profit environmental club, to examine how information and communications technologies (ICT) affect climate change.