I was asked during my HPA sustainable media session to compare the carbon footprint of a movie delivered by DVD versus one delivered by streaming. It was a good question, but one that required much research.  Here's the first half of the answer.

News Corporation has been investing a lot of time and money in tracking the carbon footprint of their DVDs, so they had a wealth of data for me to look at. After working through the numbers, here is what I came up with, using "Production" in the entertainment industry sense and including manufacture of the DVD and its package in the "Distribution" number.

So, the carbon footprint of a DVD is about one pound, with a few caveats. First, the NewsCorp numbers are based on direct bulk shipment from the manufacturing facility to a big-box store. A more complex supply chain, such as getting the DVD to a local video store, is likely to yield a higher footprint. Second, the Production footprint can be highly variable. This analysis is for the 2008 animated feature Futurama: Bender's Game. A live-action feature with extensive location work is likely to have a much higher production footprint. Third, a more exacting analysis would average production costs across all distribution, including theatrical and television, so the unit production footprint would be lower.

That almost 70% of the footprint comes from distribution suggests two things. First, a "footprint per viewing" metric would likely be less with a rented DVD than a purchased one. Second, we get a hint at the likely outcome of the final comparison with streaming/download. But what will be even more important to the final comparison is the footprint to get that DVD from the store to your house. A five mile round trip in a reasonably fuel efficient family sedan will generate four pounds of CO2, dwarfing the emission of the DVD itself.

I'll close by noting that Fox Entertainment has made considerable progress in reducing the carbon footprint of its animation productions. This DVD's Production number is 53% lower than that reported for 2007's Futurama: Bender's Big Score.

Also, see a comparison between digital and physical delivery.