By Janet Raloff

Web edition: January 12, 2009

It’s nice to be back from a much-needed long holiday break. And what present should I find in my inbox this morning but reference to a provocative news tidbit, thanks to Dave Poulson, associate director of the Knight Center for Environmental Journalism at Michigan State University. He offered a link suggesting that conducting two Google searches may generate as much carbon dioxide — a potent greenhouse gas — as boiling a kettle of water for tea.

The tea comparison sounds British, as it should since it appeared in a news item in yesterday’s Sunday Times of London. But there’s nothing special about googling when it comes to carbon footprints. All Internet searches rely on fast computers that use lots of energy directly — and even more, indirectly, to keep the electronics comfortably chill, year round.

The ST’s Jonathan Leake and Richard Woods quote Harvard environmental fellow Alex Wissner-Gross as calculating that a typical Google search generates some 7 grams of carbon dioxide; boiling a kettle releases about 15 g. Google’s search engine can offer those speedy response times that everyone prizes by employing gazillions of servers. Having the capacity to be ready for everyone’s queries means Google, Yahoo and other web searchers must have plenty of equipment standing by to jump into action whenever we get curious — and that “burns energy,” Wissner-Gross told the newspaper. He has submitted his research for publication and set up a website where we can learn more about carbon footprints for our activities.

For the record, though, I should note that Google challenges Wissner-Gross’s numbers. It argued yesterday, in a blogged response to the tea-kettle comparison, that “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.” The energy each search typically consumes, then, only amounts to 1 kilojoule, or “about the same amount of energy that your body burns in 10 seconds.” In greenhouse-gas equivalents, that’s 0.2 g of carbon dioxide, or a thousandth the output of driving the family car 0.6 miles.

I hate to admit how many computer searches we do here at Science News, but it’s probably enough in any given week to boil an Olympic pool of water, even at Google’s deflated 0.2 g per search rate.