As environmental degradation of the Earth grew, it became evident that a number of environmental problems were very large in scale. Certain types of degradation, such as large-scale air pollution, became a regional problem: in some cases, a continental problem. Transboundary air pollution from industrial sources and coal-burning power stations is an example. Some problems are even bigger, and global in scale. Such environmental misadventures are affecting or threatening to affect the entire planet. The two biggest are stratospheric ozone depletion and global warming. If they continue unabated, these two will affect every individual on Earth in one form or another. Their solutions require global efforts and co-operation.
The problems became global not only because of their scale but also due to the fact that the natural constituents of the Earth, such as water vapour or carbon, tend to circulate between their various storage places. The hydrologic cycle, discussed in Chapter 4, is an illustration. Human activities tend to alter the proportion of these constituents among the various storage places, leading to global environmental degradation. For example, carbon is stored in the rainforest. By destroying huge amounts of the rainforest and burning the biomass we have released quantities of carbon as CO2 in the atmosphere. This in turn is threatening to change global climate. When that happens it will alter the quality of life for everybody irrespective of where the lost forests were located and for whom they were cut down. The solutions of global problems require stringent regulations and the need to involve everyone. The Earth behaves as a holistic unit in such cases.