Teaching the undergraduate environmental science 1 course at UP is extremely challenging since I had to consign the syllabus to the trash bin! Why? It is because the traditional idea of chopping down the environmental system into its spheres e.g. lithosphere, atmosphere, biosphere, cryosphere, hydrosphere etc with their problems may not reflect what is happening in nature. Of course we have to introduce these "sphere" concepts because it allows us to have a good initial grasp of the various physical and biological processes happening. However in nature, what happens in the hydrosphere for example has a direct effect on the atmosphere and of course on the biosphere. All these processes are linked. That everything is linked in nature is the central tenet of environmental science and environmentalism. The natural processes are linked and so too is the damage we humans inflict on these processes. Perhaps the history of our dealings with the environment can be simply summarized...
"It is surely harmful to souls to make it a heresy to believe what is proved" - Galileo