Data centres account for around a quarter of all IT industry carbon emissions, according to a new report from Gartner.

Data centres are not the top producer of carbon emissions, however, as PCs and monitors account for 40 per cent of all output.

But the effect of data centres is rising sharply as virtualisation and increased data processing become more important.

"Data centres account for such a large portion of ICT CO2 emissions for three main reasons," said Rakesh Kumar, a research vice president at Gartner.

"There is a lack of floor space, a failure to house high-density servers and increased power consumption and heat generation. These three issues will affect the cost of running a data centre."

The emissions from such centres are rising fast, and Gartner warned that new technologies will add to the load.

Kumar estimated that microprocessor energy consumption alone will double within the next 10 years, for example.

The analyst advocates setting up sustainable IT groups within companies to monitor levels of emissions, establishing a green procurement programme and getting a clear picture of current and future energy costs.

Although PCs account for a larger proportion of carbon emissions than data centres, manufacturers are making positive efforts to cut or offset emissions. Such plans have yet to be put in place for data centres.