Does Google-Search Carbon
Measure the Wrong Number?
CARL BIALIK / The Numbers Guy / Wall Street Journal 22jan2009
Does a Google search lead to seven grams of carbon-dioxide emissions, as the Sunday Times of London reported last week? Or is it two-tenths of a gram, as Google Inc. countered on its official blog? Or is a Web query using the popular search engine a net positive for the environment?
Last week The Wall Street Journal’s Environmental Capital blog reviewed the spat. At the time, it was unclear which number was more persuasive. Today Google’s estimate looks more credible, as the Times clarified its report and an erstwhile backer of the higher figure now is happy to go with Google’s number. But both calculations are by necessity incomplete.
First, the relatively new science of measuring carbon emissions is neither standardized nor finalized. Then there’s the opportunity “cost,” in emissions, of seeking information some other way. For searches that aren’t borne of idle curiosity, the alternative may be a series of phone calls or an in-person hunt. “If you have something that can transfer electrons quickly and efficiently, that’s more efficient than trying to move around atoms, like yourself to a shopping mall,” Erik Teetzel, one of the engineers who work on data-center efficiency for Google, told me. And it’s unclear whether to measure just emissions by Google’s servers, or also those generated at all stages in between them and the end user.
The carbon-numbers controversy began with an article in the Sunday Times provocatively headlined “Revealed: the environmental impact of Google searches.” (The Times, like the Journal, is owned by News Corp.) “While millions of people tap into Google without considering the environment, a typical search generates about 7g of CO2,” the article said. “Boiling a kettle generates about 15g.”
Alex Wissner-Gross, an environmental fellow at Harvard University, was quoted later in that paragraph, but he told me, as he told other blogs, that he wasn’t the source for the seven-gram figure: “They were using numbers from elsewhere.” Urs Hölzle, Google’s senior vice president of operations, responded on the company’s blog, explaining its 0.2-gram calculation. The Times later published a clarification saying it accepts Google’s figure and was “referring to a Google search that may involve several attempts to find the object being sought and that may last for several minutes.”
Rolf Kersten, a product marketing manager for Sun Microsystems in Germany, had published the seven-gram figure in 2007 (with the details in German). After another tech blog pointed to that as a possible source for the seven-gram estimate, Kersten wrote that he accepted Google’s figure and explained possible sources for the discrepancy, including that Google’s servers are more efficient than they were when he made his calculation, and that they’re drawing on sources of energy that emit less carbon dioxide.
“The numbers cited in Rolf’s blog were done without specific knowledge of Google’s deployment, and were based on standard calculations at the time of the original post (May 2007),” a Sun spokeswoman told me. “As a result, Rolf’s numbers may vary from actual results from Google.”
The Times of London’s clarification suggests another source of the numbers discrepancy: The carbon footprint of a search depends on whether you’re counting just the emissions from servers or also those from the user’s computer. CO2stats.com attempts to take such factors into account, for a typical Web site. Wissner-Gross, the co-founder and chief technology officer of the site, said Web sites may vary depending on the time it takes to load; Google prides itself on quick loads and speedy searches.
“We’re slowly moving to a world where we’re going to see passive monitoring of all carbon emissions,” Wissner-Gross said. “We’re not quite there yet.”
It remains unclear how to assess individual computer tasks when users may leave their computers idling for hours. Even the energy required to keep a human being functioning while conducting a search represents some degree of carbon emissions. “There’s no standard protocol for measuring any individual’s activity,” said Teetzel of Google. “That’s indicative of an emerging, interesting market.”