There are two points of serious concern...
1.. The Planet can not survive if we keep on consuming natural resources as per present rate. We are not leaving any resource for next generations to come who will probably use it more efficiently. By allowing uncontrolled increase in human population and unbalance population density, it is becoming alarming.
2.. The change in proportion of population of different sects, religions and communities will lead to extinction of some races, force others to match by the growth in numbers and dominance of a group of people by mere their numbers. This will lead to change of power centers, civil rights and culture. It is high time all the governments should decide and ensure that the balance will be maintained in population of different groups.