I think a lot of people freak out when they hear the term population reduction.
If it has to be done, there are two ways of going about it - the fast way and the progressive way.
Its the fast way, i.e. killing off millions through war/starvation/disease that people understandably wont tollerate. The idea of doing this is just disgusting.
The progressive way however, is to control birth rates to an extent, eg. 1 or 2 children per family. If this was adhered to by all, along with active management and education on how to maintain and manage the planets resources everybody would win. IMHO
Peace
Iain