ABSTRACT
An old Chinese proverb states, “If we do not change direction, we are likely to end up where we are headed.” At no time has this statement been more appropriate than as it applies to humankind at the present time. Blessed with a miniscule, but unique and remarkable, speck of the universe that has conditions conducive to life, humans are on a course that, if not altered, will result in destruction of the only home that they have or ever can have. About 2 billion years ago, one other type of organism, photosynthetic cyanobacteria, used captured solar energy to produce biomass and liberate atmospheric elemental oxygen to the atmosphere, making possible all of the life forms that require this gas for their metabolic processes. This was a planet-altering process that determined the life forms that have existed on Earth in all the eons since it occurred and that caused massive chemical change, such as the formation of iron oxide deposits from the oxidation of soluble iron in water. Until now, no type of organism has caused such a drastic change on Earth, particularly in its atmosphere. However, by burning enormous quantities of fossil fuels at an ever-increasing rate, humans are well on the way to doubling pre-industrial levels of atmospheric carbon dioxide. Virtually all reputable authorities agree that this will have a signifi cant warming effect on the global climate. Whereas the atmosphere created by the humble single-celled cyanobacteria made possible the development of millions of kinds of new species, what humans are doing to the climate now will almost certainly result in the extinction of hundreds of thousands-perhaps millions-of species.
