Food security
Problems providing food for all the mouths
Desertification, soil salinity, water shortage, etc. due to high agriculture pressures
Water and air pollution, global warming
Shelter (housing)
Spreading of disease from overcrowding
Land availability
Encroachment of people into wildlife areas
Pressures on natural resources (deforestation, poaching. fisheries)
Increased need for energy and mineral resources
Economic pressures (jobs)
Political unrest in areas of scarce resources