The Carbon Footprint of Games Distribution is an analysis of game distribution that draws the counterintuitive conclusion that in many cases, digital distribution requires more energy and creates more pollution that boxed games (thanks MCV). Here's a bit:

Contrary to findings in previous research on music distribution, distribution of games by physical BDs results in lower greenhouse gas emissions than by Internet download. The estimated carbon emissions from downloading only fall definitively below that of BDs for games smaller than 1.3 GB. Sensitivity analysis indicates that as average game file sizes increase, and the energy intensity of the Internet falls, the file size at which BDs would result in lower emissions than downloads could shift either up- or downward over the next few years. Overall, the results appear to be broadly applicable to title games within the European Union (EU), and for larger-than-average sized games in the United States. Further research would be needed to confirm whether similar findings would apply in future years with changes in game size and Internet efficiency.