I'm more concerned about the types of governments that economic and political instability -- problems that are created by issues such as overpopulation -- fosters. This instability is ripe for an environment that creates overzealous dictators that create further suffering for their people.
Similarly, you can bet that we've only begun to see the problem of ethnic cleansing rear its ugly head. As populations of certain countries continue to escalate at high rates, ethnic groups in those nations will compete with one another for scarce resources. More massacres, and probably more U.S. intervention will follow. We should be trying to head this problem off at the pass. Funding of family planning is one such strategy.