I guess you're probably just saying you don't identify or maybe agree with some other environmentalists, which also makes sense. The straw ban is a great example. Sometimes you can agree on what's important but disagree about what to do about it.
I think this is the same complex process the word "feminism" gets put through. It's hard to find people who will outright say, "I think women should still have to ask permission from their husbands to seek work," for example. It's easy to find people who are quick to add, "... not that I'm a feminist or anything."
I don't know. Words are funny. At the end of the day it probably doesn't matter whether you qualify as some kind of *-ist, but those words are one way we get convinced that other groups of people are opponents, instead of peers. (... one way that unscrupulous people intentionally convince us, depending on your level of cynicism.)