A Reason for War?

I am surprised that the problem of acid rain has yet to spark a war. Of all things, the fact that one nation's polution can cause acid rain in another, can contaminate food and water, damage crop productivity, and cause illness in their people seems like a reason to go to war. In past conflicts, nations have not hesitated to introduce biological warfare, causing widespread illness and death among another peoplee. Yet, in a time when water is more scarce than it has ever been before, when half of 1% of the earth's water is available for drinking, when massive quantities of that water are used to grow corn to feed cows or cotton to make jeans or for chocolate and coffee production, nations ignore acid rain almost entirely.

By no means do I mean to complain that people are not killing each other with their hands and weapons. But I cannot help but notice that they are poisoning each other and doing so with clear consciences.