Is there a moral solution? I don't think there presently is one. But I think time's running out for us and fast. I was watching a TED talk, and the lady on there said with much dismay that the world population needs to drop by at least 75-80%. If we were to maintain our current levels of consumption and dumping crap into our environment.
And I have to say I agree. There are too many of us negatively impacting the environment simultaneously. When I see large families of 2+ I think they were arrogant to have so many children. Those kids need to be pushed hard to make ground breaking achievements and be consciously aware of their carbon footprint, if not you were selfish in self replacement value.
I try with growing my own food, not using plastic bags, recycling, and reusing, almost everything in my house is repurposed until it can't be. I use my motorcycle on average once or twice per week.
But when nature tries her darnedest to "cull the herd" out we fight back with medicine. As horrible it is to say I think we need to do what Mizaru; Kikazaru, and Iwazaru do for a few epidemics. Like I said there is no morally acceptable solution that I can tell.
The abundance of life makes life expendable, with every life lost 3 replace it and that number continues to rise with longer life expectancy. If it were a "war" for our survival I would say even a 50% loss of life would be acceptable. And I think a plague of sorts is the most "humane" which in the common definition it is not, but allow me to explain. Disease doesn't choose specifics. It doesn't target specific social classes, or race, or religion, or gays, or straight, or what ever gender people claim to be. It finds a host then it kills the host.
If humanity were to attempt to control our own population then we would be biased, I think the elitist sects of our society would deem themselves worthy of being saved. When it (my assumption) they who have most likely perpetrated the worst crimes against the environment.
The planet does not need saving, we need to be saved from ourselves. And in order to figure out a more efficient solution we need time. And less of us means more time to figure it out. Or figure out how to leave the planet and find somewhere else to muck it all up.
Anyways this is one of my unpopular opinions and I'll probably be crucified for it but I'm saying it anyways.