Disclaimer - we have a good relationship and are happy most of the time and this is a very rare occurrence.
I feel like I'm going mad when we have certain discussions.
Example: today we were talking over breakfast and I brought up a few different subjects, I was trying to get to a point and said "we know we are damaging the planet" (as in humans not just me and him) and he said "are we though?" I was 
Completely derailed the conversation which then went like this:
Me - yes we are its not uncommon knowledge
Him - how do we know that we are, how can you know
Me - (more and more perplexed) why don't you read up and learn more about it before we discuss it anymore
Him - (getting huffy) you can't have a conversation with you this is always your reaction
Me - because you always question the weirdest things, are you saying we are not damaging the planet?
Him - maybe, I don't know how do you actually know
Me - how do you not know?
Him - but we always discuss these things and you can never elaborate when I question things
Me - do you want links? I can send you links.
From then it went back and forth with his points being:
- we are just speeding up the process it probably would've happened some other way if it wasn't for us
- how do you know what damage we are actually doing
Upon me asking if he's not concerned about the world we are leaving for our DCs - how do you know future generations won't be inhabiting a different planet after this ones done - I pointed out why can we not just look after the one we have?
- if it's not us it would've been something else
- you are talking about deforestation but in other places they are replanting trees
- maybe it's all just part of evolution
- how can you know it's us doing the damage - what else?!
When I talked to him about the images I showed him of polluted oceans and suffering animals - what is that actually leading to though?
I don't know if he's trying to very poorly suggest different theories and have a "what if" type discussion or maybe he's got valid points and it's me being daft?
Is he just looking for me to throw evidence his way?
I'm not the best at debates as I don't get my point across very well but I honest feel like banging my head against the wall afterwards. In my head I'm just going "are you seriously questioning IF we are damaging the planet?!"
AIBU and should I be more open to discussion or is he BU and talking crap?