Automation and telepresence technologies could cut $900bn a year from the world's energy bill.
Malcolm Johnson, director of the standardisation bureau at the International Telecommunications Union (ITU), told Computer Weekly that this saving was possible if technologies such as these were extended across all industries.
"A single datacentre for a search engine company consumes as much energy as a city like Geneva, which has 812,000 residents," Johnson said.
The IT sector, which produces 2.5% to 3.5% of the world's greenhouse gasses, is addressing its own carbon issues by developing equipment that uses less energy and runs at higher temperatures, cutting the energy needed to cool it, he said.
High-speed communications networks need fewer switching centres, which need cooling. They also make possible applications such as home working and telepresence, which cut the need to travel, he said.
Applied correctly, IT could help cut emissions in other sectors by up to 40%. Key sectors where IT could be effective include energy production, transport, construction and information processing, Johnson said.
The ITU has developed a methodology for assessing the impact of the information and communications sector on greenhouse gasses. It hopes to have it accepted as a standard model for other industries at the Copenhagen convention on climate change in November, said Johnson.
The ITU also hopes that the convention will accept the ITU's method of assessing the impact of IT on other sectors of business in cutting their own greenhouse gas emissions.
The ITU showed how the use of IT could save energy in developing the methodology. Contributors around the world have met 31 times, 28 of them in cyberspace, and produced the standard in just nine months. An ITU standard usually takes years of face-to-face meetings to agree, said Johnson. "This saved thousands of tonnes of CO2," he said.