The essay Lifeboat Ethics: the Case Against Helping the Poor from 1974 is probably the essay available online that is more applicable to the current discussion.
I do not yet have a well-formed opinion on this one way or the other, I simply find Garrett Hardin's arguments to be thought-provoking. Saving millions of lives will mean that those millions of lives need to be sustained in some way. The resources to do this have to come from somewhere. By saving those millions of lives is that going to lower the quality of life of millions of others? It is a tough problem with, as Hardin mentions, "no technical solution".
Lifeboat Ethics: the Case Against Helping the Poor essay: http://www.garretthardinsociety.org/articles/art_lifeboat_et...
Tragedy of the Commons essay: http://www.garretthardinsociety.org/articles/art_tragedy_of_...