A billion people live in extreme poverty in our world today. It is these people who are most at risk from the threats of environmental damage, climate change and the consequent loss of resources.
Most of these people live in developing countries. Some countries find themselves in a "self reinforcing poverty trap"; poor people in these countries have large families to counter high levels of child mortality and to sustain them in their old age. At societal level however, the resultant overall numbers of population together with limited resources condemn their people to ongoing poverty.
Concerted action is called for on the part of the developed world. Humanitarian assistance and development aid to provide education, encourage female empowerment and ensure access to family planning resources are necessary to help developing countries break out of their poverty trap.
Other countries are developing unevenly, with huge numbers of extremely poor people living alongside pockets of urbanised modernity. For some people, particularly in rural areas, large families remain a way of boosting the family's ability to generate income. However, this is becoming less true as population growth limits available per capita land resources.
For others, a desire for fewer children is frustrated as a lack of health and transport infrastructure limits access to the reliable supplies of contraception they need. On the other hand, children may be a parent's only form of security in old-age. Where poverty results in a high rate of infant mortality, this is a further incentive for people to have more rather than fewer children.
Read more about poverty.