It depends on what the end objective really is. What is the goal?
Environmental Concerns benefit from buying everything locally you possibly can. The Macrobiotic diet tries to acheive this end. Veganism also addresses this issue by refraining from supporting dairies and slaughterhouses, which use massive quantities of water and have terrible waste runoff. The Macrobiotic diet does address green house gas concerns and would have a noticable effect if everyone were to adopt it.
Buying organic will definitely help reduce the chemicals used in produce and produce all-around healthier produce, and protect surrounding wildlife from chemical pollution. It alone will not stop supporting slaughter houses, though.
I don't really know that either of these approaches are any less "extreme" than veganism. I think if everyone were to embrace at least one of the approaches, it would benefit the environment tremendously, possibly improve overall health, buy veganism would be necessary to stop animal cruelty. I think veganism is the most comprehensive approach, but if it is not the most adoptable, I sure hope one of the other two approaches become pervasive.