If you'd want to make a regional model of reduction requirements for a global footprint, the 'contraction and convergence' idea taken from the discussion over greenhouse gases could be applied.

The global footprint measure expresses the impact individuals have on a global level. I don't know if we should instead move towards a measure of the impact nations or regions have on the global level. I rather think we should move towards a similar per capita footprint than to say that in a sparsely populated country or region, people can of course have a bigger footprint.

Generally I don't know if we should expand the politics of setting top-down reduction targets for countries or regions to this area. Setting deadlines causes people to shift their efforts towards the future (due to the 'discount rate' or 'rate of time preference'). There is evidence that this also goes for politicians. Like Schellenberger & Nordhaus I would prefer to see a 'breakthrough', though my conception is different from theirs.

one thing we know is that forcing women to have unwanted babies is insane.  not all mothers are "eager", as the steady rate of abortion-seeking regardless of legal strictures demonstrates;  whether abortion is legal or not, safe or not, the percentage of unwilling mothers seeking it does not vary greatly -- the only notable difference between regions where it is legal and those where it is forbidden seems to be in how many women die annually from incompetent abortion procedures.  

now, a Swiftian analysis would suggest that killing women is a far better method of population control than mere contraception or abortion, since killing a woman removes from possibility all the children she might eventually have;  and I do have to wonder sometimes whether the deeply troubling global rates of femicide and selective abortion of female fetuses (particularly in Asia) are any kind of unconscious popular response to overcrowding, hunger, and insecurity.

which leads me off in another direction:  there is much debate over possible outcomes of large populations skewed strongly to a dearth of females:  
here a recent book on the topic is reviewed,
here a western blogger scoffs at concerns over the projected imbalance,,
and here an important fact is noted, too often overlooked, that in natural disasters (as in war in occupied civilian areas), the majority of the victims are women:  According to the report of the international aid group Oxfam, the tsunami has created a severe gender imbalance in the devastated regions. The report suggested that it killed four women for every man, which means that in some villages "up to 80% of those killed were women." According to the Sunday Times, in the Acehnese village of Kuala Cangkoy, for instance, around 117 of the 146 victims were women.

The difference between theory and practise in practise ...