A pinch of salt
So the competing claims of Google and Wissner-Gross differ by an order of magnitude of 35, leaving us no wiser than before. However, what this article does reveal is how misleading and counter-productive a lot of green hysteria is.
We're all henpecked about our ‘carbon footprint' the whole time, leading us to make token concessions in order to be able to occupy the moral high ground when indulging in a spot of collective eco hand-wringing.
However, it seems to be almost impossible to produce definitive statistics on this sort of stuff, so every eco scare needs to be taken with a massive pinch of salt - which although free of carbon itself, uses four tonnes of CO2 per grain to extract. Not really.
Further research into this matter would certainly have required more than two Google searches, so we decided to do our bit for the environment and have a cup of tea instead.