Drew Bennett, well, I guess you are close to the truth. The column with "Reasons for global warming" has information about it as a chemical process (about CO2, Sulphur, CFCs, and Methane and their contributing to global warming). The column with "Reasons of global warming" is about human impact in the production of these gases (technological advancement, industrialization, urbanization, and also deforestation) so I thought that these constructions have different meanings and I wonder how to use them in other situations. But native English speakers have written below that only one variant is possible - "Reasons for global warming".. so maybe there is a mistake in this article. Thank you anyway!