The blogs are ablaze. That bastion of liberalness and social progress, Google, has been indicted with a carbon crime -- two google searches alone are responsible for the emission of 7g of CO2, "enough to boil a kettle of water." Google, a company that has invested millions in solar technology, promptly rebutted the claim, saying that a search represents a tiny fraction of that amount.  But in typical Google fashion, they will not release the stats. So we are left to wonder. 

One of my favorite carbon bloggers in the UK, Leo Hickman, did some number crunching and is skeptical. He also points out that Alex Wissner-Gross, the man behind the 7g figure is the co-founder of, a company which sells carbon credits to internet companies to offset their carbon footprint. Little conflict of interest, no?  If anything, Hickman states, should be congratulated for a fabulous PR campaign that raises an important fact -- information technology consumes a great deal of energy and is responsible for an estimated 2-3% of global carbon emissions.

Here's the back of the envelope math:

* approximately 500 million google searches every day (estimates vary)

* x 3.5 g per search = 1.75 trillion grams / 1 million grams per ton = 

* 1,750 tonnes per day x 365 = 638,000 CO2 tonnes per year

And thats just for searching.  It seems safe to assume that Google uses an equal portion of its servers for its hundreds of other projects -- phones, software, advertising services, webware, apps and on and on. So lets double that number to 1.3 million tonnes/year. That's more than many countries. But it is still certainly within the realm of reason.

As Alex Wissner-Gross describes below, his numbers are based on energy consumption for a typical website -- 20 mg of CO2 per second. Google, with their sophisticated server network, claims to be significantly less. But one great thing about this factoid, accurate or not, is that it makes us think about how many of our impacts on the environment remain totally invisible to us.