Chikyuu Shoujo Arjuna, Ao no 6-gou Recommendations
The idea that technology has doomed mankind's future by not respecting nature is approached in both animes. In Arjuna, polution, a by-product of our advancements in tech, is damaging earth, hence, it is up to Juna to heal the planet. Meanwhile, in blue sub. someone tries to protect the environment by eliminating mankind.
They show differents approaches on how to tackle the overexploration of resources, and lack of respect we have by our planet.