The contribution of population growth to the environmental crisis is a very controversial topic. Consequently, a wide range of environmental problems has emerged; those problems include anthropogenic-
- Climate change ('global warming')
- The depletion of stratospheric ozone (the 'ozone hole')
- The acidification of surface waters ('acid rain')
- The destruction of tropical forests
- The depletion and extinction of species, and the precipitous decline of biodiversity. Yet, while all of these problems have physical (environmental) manifestations, their causes - and their potential solutions - are invariably bound up with human attitudes, beliefs, values, needs, desires, expectations, and behaviors. Thus the symptoms of the environmental crisis cannot be regarded purely as physical problems requiring solutions by environmental 'specialists'; instead, they are intrinsically human problems and they are intimately related to the question of what it means to be human.