A reader writes:
While I understand Ms. Butler's point about the environmental impacts of e-mail traffic (as an energy consultant, energy use of data centers is something I think about more than most I would guess), I think she misses a few key points in her article.
The first would be the fact that memory space is highly reusable. If I get an email with four photos attached, and keep it in my inbox for the rest of all time, then yes, there is a real increase in the demand for storage and the energy used by that storage. But looking at my Gmail account right now, I am using 13% of my 7486 MB of storage. There is plenty of unused capacity sitting there generating CO2 whether or not I'm using it to store data, and if I delete that picture (as I usually do, being a fan of a clean inbox) then that picture has not caused a real, sustained increase in the amount of energy needed to store my data.
And I can't say for sure (given that her source didn't go into the details about his 17.5 kettles number), but that seems more like a lifecycle-analysis assuming the pictures are kept rather than viewed and deleted to free up memory space. The same thinking can apply to the power use of the devices used to view the e-mails: I'm using my computer all day, so the marginal power consumption caused by receiving an e-mail with four attachments is probably negligible, and could even be negative; if I were running a program that required all of the computing power of my machine, but replaced some of that time with looking at LOLcats that my friend had sent me (without shifting the higher computer to another time), then distracting e-mails could actually prove a net power saver.
Another thing that Ms. Butler ignores is the replacement of older forms of media with digital versions. I don't know the actual tradeoffs here, but the relative energy intensity of getting a photo printed at your local photo center as compared to the energy required to view it on a computer needs to be a part of this equation. Yes, digital photos have drastically increased the extent of photo taking and sharing, but if each print takes 1000x (a completely made up number) as much energy to generate than its digital counterpart, then the net impact of the photo attachment is severely reduced. The same goes for most other types of attachments; where I used to send a mixtape, I now send mp3s; where I used to send invitations, I now send an evite, etc.
This is not to say that we need not be concerned about the energy use of data centers, but rather that the situation may not be as dire as Ms. Butler implies.