A comment to my post on the electrical failure that shut down the Large Hadron Collider (LHC) suggested that scientific research should have some kind of carbon footprint analysis.  Given the large energy demands of the LHC, I understand the point.  And that person is not alone.  Nature News reports on the carbon footprint calculations made by a Norwegian researcher for him and his colleagues and the Norwegian Institute of Air Research.  The estimated footprint (travel alone) was 3.9-5.5 tonnes of carbon dioxide per year.  This footprint is comparable to that of other professionals in science and other fields that travel frequently.  The news report (and the article) focuses on the carbon footprints associated with formal and informal scientific meetings, it seems reasonable to extend such analysis to large research facilities and instruments.  Can someone tell me how many trees I should plant to offset the new cyclotron?