Green Hosting - Pros and Cons
The pro is that maybe it's actually environmentally friendly - hence, easing your conscience. On the other hand, though, the con is that it indeed is a con and that it doesn't make a difference overall and/or it simply isn't helping the environment. Myself, I think it helps the environment, but overall, it might not be making a difference. Also, there are probably ways to make amend for hosting damage outside of buying green hosting. For instance, GoDaddy stopped mailing out paper invoices etc..
Personally, I think that green hosting is just a marketing/public relations trick. I'm sure it has its benefits but I don't think that it will make a big enough difference in saving the environment that makes it worth it. It's just a marketing trick that allows them to try and target those that are trying to save the environment by being careful about the things that they use. It also allows them to charge slightly higher for their services without their customers complaining too much. Maybe one day it will be something that a lot of people will use and will genuinely make a difference but for the moment it's just not worth it.
I have become very skeptical of environmentally friendly claims. In fact, I have become skeptical of many many green claims, like organic farming. Environmental impact tends to be far more complicated and cloudy.
One example is all the controversy and uproar over the Keystone oil pipeline. Does anyone really think to transport that oil by train is the more environmentally friendly method?