First of all, well done you! I can imagine this has taken so much work and a lot of thought and to get a whole picture book laid out like this, illustrations included, it is definitely something to be massively proud of!
Have you seen Michael Morpurgo's 'Grandpa Christmas'? It only came out recently but it is beautifully illustrated by Jim Field and is about looking after the planet, it might be something to have a read of for reference or it might help you to steer your wording in a slightly different direction. If you're aiming for this to be a 32 page picture book, then I think there is too much wording at the moment.
You have some lovely compositions and expressions going on within your illustrations, but maybe some aren't needed as your images and text need to be able to breathe (if that makes sense?). Your last page for example, with the children standing on top of the world, I think this would work beautifully as a double page spread, it would be a lovely image to end your book on and then the text would work a better.
I don't think all of your pages should have a plain or white background either, maybe look at incorporating a few more full bleed illustrations or even having more like your first spread, where it overlaps onto the other page? That will again, give your text a bit more room to breathe.Be careful not to make your vignettes too big either, you don't want to overcrowd them 🙂
It's worth looking at lots and lots of successful picture books that are out there, to get an idea of what works and what publishers/art directors may want to see. Your words and pictures have to compliment each other throughout the book 🙂
Brilliant work though, I do like the subject matter and I can imagine it's definitely something publishers would be interested in! All the best with it!