Dr Wissner-Gross's study claims that two Google searches on a desktop computer produces 14g of CO2, which is the roughly the equivalent of boiling an electric kettle.
Just running your own old crappy PC for 5 minutes to read the results would take about the same though.
Google however claims two searches would be less than half a gram combined.
Update: Wissner-Gross says now that the Times did not quote him correctly:
Wissner-Gross wrote:Our work has nothing to do with Google. Our focus was exclusively on the Web overall, and we found that it takes on average about 20 milligrams of CO2 per second to visit a Web site.