noun
Refers to the ideology or movement advocating for the protection of the natural environment.
彼は環境保護主義の立場から、その開発計画に反対した。
He opposed the development plan from the standpoint of environmentalism.
環境保護 is the general concept of environmental protection, while 環境保護主義 specifically refers to the ideology or movement.
Compound of 環境 (environment), 保護 (protection), and 主義 (doctrine/ism).