Light green is a conscious choice. Dark green will most likely be imposed by geology. Hopefully they will reinforce eachother. A mosaic of many shades of green, some chosen and some imposed is unfolding between social economic classes, cultures, countries, individuals.  
Exactly--"Light green is a conscious choice".  It is like the difference between Efficiency (getting the same performance or utility for less energy), Conservation (voluntarily sacrificing utility to save energy), and Demand Destruction (involuntarily sacrificing utility to save energy).

If we can at least get a large number of people to do just a little in the way of conservation, that is as good or better than a few people doing a lot.  We also need to educate people better to recognize the alternatives out there (e.g. compact fluourescent bulbs, especially now that they have the warm-white colors) really involve no sacrifice in utility (except the modicum of effort to find something that is not sold at Walmart).

I know Jevon's paradox and all that but action now will hopefully moderate the downslope.