@Gamer999 the problem of the AI using the wrong units to clear away invaders is a difficult problem to solve. The reason it happens is that the AI's decision making process basically just involves them cycling through each of their units one by one and looking for the best thing that the unit could do. There are very few circumstances where the AI will take into account what its other units are doing. It just looks for the best thing each individual unit could do.
So, if the AI is trying to decide what to do with a war elephant, they might see a spearman and think "well, my attack odds aren't too bad - and I really want to get rid of that spearman. So I'm going to attack." They don't look to see if there is some other unit who could do a better job.
This is behaviour is due to a flaw in the system; and that flaw causes other problems too. I think the best way to solve it would be to completely rewrite the AI so that instead of cycling through each unit and asking "what should this unit do", it instead should create a list of objectives and then cycling through the objectives and ask "which unit (if any) should do this". (Although, such a system would have other problems...)
Anyway, the upshot is that this kind of problem is difficult to completely fix. I don't intend to make any major structural changes to fix it, because I don't think it would be worth it (and it might not work well anyway) - but I might be able to make some tweaks to make it less likely for the AI to make mistakes like that.
Ok. Nice to know. Great if you can make AI little less likely to do this.
As for the scaling of global warming. I'm not certain what you mean about it becoming 'unplayable'. Do you mean that global warming becomes extremely strong well before the end of the game? If you have some particular example of a map / settings combination where this happens, I'd like for you to post about it in the GW feedback thread. Regardless of whether or not there's an option to turn GW off, I'd like for it to work properly on all maps! And as for having an option to turn it off... does anyone happen to know if it's possible to add / change the available options in the custom-game settings screen independently of all custom maps? In particular, is there some way I could add a new dropdown menu to control the strength of global warming; and change the multiplayer options so instead of a checkbox for 'simultaneous turns', there's a dropdown menu with 3 options (sequential, simultaneous, and a new semi-simultaneous option)? - If this stuff can be added to the general game options (not the map settings) then I might implement it... but otherwise I don't think there is a suitable place for a 'no GW' option.
For earth maps I have played mostly Rhyes earth with enlarged europe and as far as I remember from old earth game that I had played very far into future era enviromentalism with public transportation and recycling centers wasn't enough to stop it. The counter wasn't going down in the domestic treshold neither in the global one. I had many factories and industrial parks, the cities weren't too big. AI also seemed to have very little interest to change situation. It doesn't make the game unplayable for other than going long into modern age (where you could change the course), I was really meaning that I like to play some modern age scenarios so it's pretty much unplayable for that in the long run.
Some mods like Fall from Heaven has extra ingame options for some features if you would have use for it, but I don't personally know how it's included.
I'm however unable to play the game for now because my pc is broken but I'm planning to play modern era based earth scenarios in future and I could then post more about if it's still useful information.