Google searches are responsible for high carbon emissions, according to an academic from Harvard University who claims that making two internet searches via Google produces about the same amount of carbon dioxide as boiling a kettle.

Dr Alex Wissner-Gross, a physicist from Harvard University, is conducting research into the environmental impact of "googling", amid concern of the growing environmental impact of IT. Dr Wissner-Gross's study found a typical Google search on a desktop computer produces about 7g of carbon dioxide. Two Google searches are therefore the equivalent of boiling an electric kettle, which produces about 15g of emissions.

He estimates the emissions are caused both by the electricity required to power a user's computer and send the search request to servers around the world. As Google makes use of multiple data centres in order to achieve fast results, Wissner-Gross therefore believes that Google searches produce more emissions than some of its search rivals.

Wissner-Gross has also estimated that browsing a basic website generates about 0.02g of CO2 for every second it is viewed. Websites with complex video can be responsible for up to 0.2 g per second, he estimates. His website, www.CO2Stats.com, is designed to allow webmasters to make their sites greener in an auditable way.

"Google operates huge data centres around the world that consume a great deal of power," he reportedly said. ""A Google search has a definite environmental impact."

"Google are very efficient but their primary concern is to make searches fast and that means they have a lot of extra capacity that burns energy,"

Google however has countered the figures. "We thought it would be helpful to explain why this number is *many* times too high," said an entry on the official Google blog. "Google is fast - a typical search returns results in less than 0.2 seconds. Queries vary in degree of difficulty, but for the average query, the servers it touches each work on it for just a few thousandths of a second."

"Together with other work performed before your search even starts (such as building the search index) this amounts to 0.0003 kWh of energy per search, or 1 kJ," Google said. "For comparison, the average adult needs about 8000 kJ a day of energy from food, so a Google search uses just about the same amount of energy that your body burns in ten seconds.

"In terms of greenhouse gases, one Google search is equivalent to about 0.2 grams of CO2," the search engine giant claimed.

Last November, the European Commission launched a code of conduct for data centres, in an effort to tackle their increasing power consumption, and minimise the related environmental, economic and energy supply impacts.

Back in October, Google, which had up until then been remarkable secretive about what goes on inside its data centres, claimed that its server operations were "the most efficient in the world."

Many believe that Wissner-Gross's claims require closer scrutiny before his estimations can be accepted. For instance, there is no indication of Wissner-Gross considers to be a "typical Google search". Does his calculation assume that every search is generating the same amount of carbon? Or has he just divided the average search volume by the total amount of carbon generated?

Presumably then, boiling a kettle for a cup of tea whilst doing multiple Google searches, is even more destructive?

It is also worth noting that headline grabbing figures such as from Wissner-Gross, doesn't take in account the displacement of CO2 emissions created by the use of the internet, email, and/or telecommuting, compared to physically travelling to the library or moving a piece of post such as a letter from the house to its destination.