But then again he did mention "bringing to ruin those ruining the earth", and that was probably thought of as an impossibility back then, that people could actually ruin the earth.
We assume that "ruin" refers to pollution and environmental devestation. People have made that association ever since these have become plausable in the 20th century. However, from my humble examination, "ruin" in the Bible never (that I'm aware of) refers to environmental devestation. The "ruin" I've seen in the Bible typically refers to war and its after affects. Since this has happened throught history and all over the 'Earth' the scripture probably was intended to mean that God will "bring to ruin (attack) those who are ruining (attacking and destroying in all parts thereof) the Earth".
The Bible is silent about environmental matters. If God were outraged at environmental irresponsibility he fails to teach this in the Bible. This scripture, if intended to address this future development, would be a single, isolated instance of his dissatisfaction over it. In other words it just doesn't make sense that God would reveal, in Revelation of all places, his standards for environmental stewardship. So with that in mind I think the 'ruin' John writes of is the ruin cited elsewhere i.e. Earthwide instances of destruction typically brought on by marauders.