I am certain that it has already been said in this thread. Better living conditions and assimilated cultures tend to make for smaller families than would have been had if people remained in 3rd world conditions.

Using overpopulation and bid to save the planet as a basis for argument to curtail immigration is just trying to cover fear of people who are different, especially if one believes those different people are using up resources, taking jobs they are not entitled to.

Don't fear the wrong thing. The danger is leaving people in squalid living conditions, where industry goes in to take advantage of cheap labour and lax environmental regulations. That's what is killing the planet. That is what takes jobs away from industrialised nations.