The world’s data centres are responsible for the same volume of carbon emissions as the average European country, and more than double those of Finland and Portugal.

Data centres account for almost a quarter (23 per cent) of the 580 million tonnes of CO2 released annually by the production and use of computer systems, according to the latest research from analyst Gartner.

And despite the development of more environmentally-friendly technology, the situation will only get worse, according to Gartner analyst Rakesh Kumar.

“Organisations are growing their infrastructure exponentially and emissions from data centres are expected to double by 2012,” said Kumar.

Power-hungry hardware and lack of floor space ­which increases cooling requirements ­are key factors in spiralling energy consumption.

And despite awareness campaigns, many businesses still do not appreciate the disproportionate amount of power used by their data centres.

The issue is starting to appear on firms’ radar, but a lack of coherence in government policy is slowing progress, said Ollie Ross, head of research at blue-chip user group The Corporate IT Forum.

“Big firms need far clearer guidance about what legislation is intended around the production of carbon emissions,” she said.

Regulation of renewable power supplies is an area where the government could have an immediate effect, said Ross.

“The high costs of renewable power are holding back many large firms,” she said.

“IT chiefs are confident that costs will drop as demand grows and government could play an influential role in encouraging that demand.”

Liberal Democrat environment spokesman Chris Huhne said: “If you simply compare the costs of renewable energy with the same amount of electricity from fossil fuels then there is inadequate incentive to switch.”

A further danger is that rising UK costs will push data centres offshore, where environmental regulations may be more lax, said Greenpeace campaigner Iza Kruszewska.

“The impact will be increased as sites spring up in developing countries with less efficient technology and higher temperatures,” she said.

Europe’s average national CO2 emission level is 134 million tonnes, according to the Carbon Dioxide Information Analysis Centre.