Businesses may be forced to ration their use of the internet and e-mail as energy costs rise and governments impose higher taxes on carbon use.
Liberal Democrat peer Lord Redesdale warned IT managers that businesses would have find more energy efficient ways of using IT, as governments become more serious about carbon reduction.
Sending a simple e-mail generates three grams of carbon, an e-mail with attachments generates 50 grams, and e-mailing a video is equivalent to boiling two kettles, Redesdale told IT professionals at an industry conference.
"In the future, carbon and energy consumption of the internet is going to be a principle energy consideration. Companies will say there is a limit to how many e-mails you can send before the cost comes out of your departmental budget," he said.
Computer networks already consume 6% of the UK's total energy supply - more than twice the energy needed to deliver a water supply to the UK's 60 million residents, said Redesdale.
As energy costs and carbon taxes rise, service providers such as Google may be forced to reconsider whether they can afford to continue offering search services free of charge.
Cloud computing may only be a solution if businesses can find ways of reducing the cooling costs of their datacentres, said Redesdale.
"People are migrating to the cloud, but we should start thinking about whether moving to the cloud is actually reducing energy consumption. Cloud is great if you can build all your datacentres in Iceland. There is no point building datacentres in India if you have to build power stations next to them," he said.
Rising energy costs and carbon taxes will mean that businesses will be forced to simplify the IT systems they offer their employees.
This could mean giving them simpler desktop terminals rather than fully fledged PCs, said Redesdale, speaking at the Fast Ltd user conference.
"Why do you need a Ferrari on your desktop when you can use a bicycle? People will complain at first but they will get used to it and accept it," he said.
Businesses will also need to tackle the contribution IT makes to air conditioning costs. A significant proportion of office energy consumption comes from having to remove heat generated by office lighting and computer equipment, making energy-efficient buildings a priority for businesses in the future.
The government has given a commitment to reduce carbon emissions by 80%, and has already announced carbon taxes, in the form of the Carbon Reduction Commitment (CRC).
Within four years, the UK will be importing 80% to 85% of its natural gas and will have to bid on the world market for a shrinking resource, putting further pressure on energy costs.
"The government is looking to reduce carbon emissions across every aspect of government. You may not see it happening, but you will feel the effects," said Redesdale. "How are we going to run our expanding data network on 20% of the carbon emissions we had in 1991. As an industry, can you survive that ?
"The tipping point has already been reached. CRC will bring in £50m to £100m. That figure is going to go up," he said. "This is a logical argument that politicians are starting to get."