Brian, I do not know whether Manfred is right in "green" terms - auditing the total environmental/energy impact of any process is often much more complex than it might at first appear. However, his second point is about the historical longevity of images and, in that regard I definitely support his point, and I think it is sufficiently important to digress from the main point of your thread for a moment.
Although it is sensible to back up your work on hard disks (wherever they are located), I suspect that those of future generations are more likely to see your own selection of photographs from your image store, if you commit them to the easily tangible and visible form of good quality medium-sized prints (e.g. 8x10). I would guess that many of us enjoy viewing decades- or centuries-old prints. Yours would have a reasonable chance of being seen long after old electronic storage technology at home has become obsolete and old files not converted to the new, and long after "cloud" passwords are forgotten or accounts have been closed down or data has been lost by catastrophe or terrorism.
As for: "I rather doubt that the world will miss many or any of my shots in a hundred years," who are you to judge? I would grant you that perhaps "the world" is going a tad too far, but there may be many individuals in the future who would enjoy viewing your work.
Philip