I understand the importance of environmental protection, but not enough to change my behaviour.
I understand protecting the environment is important, but I can not take it seriously enough to change my behaviour.
I understand the importance of environmental protection, but not enough to change my behaviour.
I understand that protecting the environment is important, but I can not take it seriously enough to change my behaviour.
上記二つとも同じ意味になりますが、
the importance of environmental protection: 環境保護の大切さ
(that節以下が)protecting the environment is important: 環境を保護することは大切だ
となっています。
度合いに対しては「enough: 十分な」を使って、not enoughとすれば伝わるでしょう。
参考になれば幸いです。