12 Biggest Environmental Problems according to Jared Diamond (author of Collapse)

A) Category 1: Destruction or loss of natural resources:

a) Destruction of natural habitats

b) Overfishing

c) Loss of biodiversity, including genetic biodiversity

d) Degradation and loss of soils

B) Category 2: Ceilings on natural resources

a) Depletion of major energy sources

b) Depletion of water resources

c) Photosynthetic ceiling is being reached

C) Category 3: Harmful things we generate or move around

a) Toxic chemicals

b) Alien species

c) Atmospheric gases

D) Category 4: Effects of increase in human populations

a) Human population growth and size

b) Per capita impact