Audio and video-conferencing by employees of British Telecom saved more than 150 million miles of travel last year, according to the UN Environment Programme.
And increased tele-working by staff of the US telecom giant, AT&T, avoided 110 million miles of car travel, saving almost 50,000 tonnes of CO2 emissions. AT&T also saved over 73 million sheets of paper by converting to intranet "paperless office" systems.
These results were announced by UNEP to mark World Environment Day today, as part of a global initiative by telecom companies to promote business practices that save energy, minimise waste and help bridge the digital divide.
Called the Global eSustainability Initiative, it brings together some of the world's biggest information and communications technology companies, including BT, AT&T, Deutsche Telecom, Cable & Wireless, Ericsson, Marconi and Telenor and Lucent Technologies.
Mr Klaus Topfer, UNEP's executive director, said modern telecommunications, by transforming the way the world works and cutting the need for travel, "offers hope for reducing some of the great environmental threats of this new millennium, such as climate change".
One of its key contributions was in the transport sector, he said. Video-conferencing, tele-banking, tele-learning and tele-shopping could reduce traffic, leading to less congestion and pollution and the emission of greenhouse gases, the major cause of global warming.
The theme of World Environment Day this year, "Connecting with the World Wide Web of Life", is intended to highlight the link between humankind's development - and, ultimately, survival - with the delicate balance of the natural world on which we all depend.
In Turin, which is jointly hosting the annual event with Havana, a new survey, the Millennium Ecosystem Assessment, will be unveiled by a network of scientists and other experts; it aims to fill important gaps in our knowledge of threats to fragile habitats and ecosystems.
The survey will be using a unique set of 16,000 satellite images, donated by the US National Aeronautics and Space Administration, which show changes in coastal areas, countryside, mountains, wetlands, agriculture and urban sprawl since the 1992 Earth Summit.
Turin is also hosting its first biennial International Eco-Efficiency Fair to showcase the latest developments in this area, which Mr Toepfer said would be crucial in helping to de-couple economic development from energy use. This was "at the heart of the fuel debate", he declared.
One of the workshops in Havana will attempt to develop guidelines for the import and export of genetically modified organisms, focusing in particular on how developing countries can acquire the scientific skills to assess whether a shipment of GMOs can be safely imported.
Mr Jorge Illueca, a senior UNEP official, said it was appropriate that this workshop was taking place in Cuba because it was one of the developing nations at the forefront of the biotechnology revolution, with exports in this category worth $900 million in recent years.
But in a message to mark World Environment Day, the UN Secretary-General, Mr Kofi Annan, said it was not scientific research but political and economic factors that would determine whether the knowledge accumulating in libraries and laboratories would be put into practice.
