Some other thoughts for ways to improve Environmentalist:
1: Give a discount on environmentalist resolutions in terms of influence cost to propose and a flat unity gift for all environmentalist empires in the GC any time one passes
2: Give extra unity/amenities every tier of environmentalist resolution, instead of just once mid-tree
3: Make tier five of environmentalist tree give every empire Environmentalist and remove Relentless Industrialist much like T5 Reverence for Life makes all robots become rogue servitors
4: Give an empire wide +1% diplo weight per natural blocker at some point in the environmentalist tree (this benefits environemntalist the most because they are the only ones likely to have any
5: At tier five in Environmentalist add a planetary decision to add (1/2 planet size) unremovable natural blockers to a planet in exchange for making it a Gaia world, basically a reverse project cornucopia "By setting aside most of the usable land on this planet we can keep the world pristine and in balance, meanign the lands we do set asside for use will be more efficent thanks to more stable weather and a healthier bioshphere"