This portrayal of Poison Ivy isn't accurate to the comics. The actual Poison Ivy doesn't care about saving humanity from climate change, she only cares about saving the plants. She murders vegetarians in retaliation for eating plants. She thinks plants have feelings, and she's wrong. She's not an environmentalist, she's a plant supremacist.
Poison Ivy would kill all off all the birds that eat berries, and drive the berry producing trees to extinction from lack of pollination in the process. She's not a rational thinker.
everything gotta have some weird nuance these days though. Can't just have the green lanterns either, gotta have red, blue, yellow, white, black, etc. Can't just have the speed force, gotta have a whole cosmology there too. It's a fuckin mess.
The Green is a collective consciousness, not an individual consciousness. If I kill a single neuron in your brain, do you feel pain? No. The individual plants don't have their own feelings. The Green is a big picture phenomenon, but Ivy is incapable of big picture thinking. She sees a human trimming a hedge and she goes apeshit. The problem is that Ivy's powers project a consciousness onto plants. She gives them the gift of sentience. In other words, she's the one making the plants suffer, and she can't see that.