Introduction

     The issue of potential climate change, and the relation of various human activities to that potential change, looms as one of the greatest challenges facing humanity in the next millennia. The principal problem that makes this issue so important and, potentially intractable, is that most contemporary Western culture, and increasingly Eastern and Southern culture as well, is organized to generate more wealth through economic activity. Since the basic way that humans generate wealth is through carbon fuel-based industrialization, the pressure for increasing economic activity means essentially that all of human society is organized de facto to pump more carbon dioxide into the atmosphere.
     There is a great deal of debate about the climate change issue, as indeed there should be for a problem of this magnitude. Since much of our economy is based on the very activities that generate the problem, and almost no one wants to be poorer, we have some very difficult decisions. Not surprisingly, interest groups and individuals with strong vested interests in the status quo vehemently oppose any restriction on the use of fossil fuels and they challenge the science of those who have argued for a large impact of human activity on climate. Indeed, it is interesting to see how many persons with little expertise in climatology have become self-appointed experts on climate change.
     Reflecting the contentious nature of the debate, the two largest industries in the United States have different views on climate change. The automobile industry opposes any restrictions on the use of fossil fuels. On the other hand, the insurance industry is concerned about that the much larger payments they incurred in the 1990s due the many additional severe climatic events (hurricanes, tornadoes, etc.). The unprecedented floods of 1993 caused $20 billion damage, the droughts of 1988 $39 billion. Scientists suggest these could be due to a warming climate, and is just a precursor of even worse climate conditions ahead.
     Given the large stakes, the fact that different players are likely to be effected in very different ways, and indeed a general widespread concern for the state of the Earth, we think it is important for a much broader public to understand the full nature of the problem. This includes the fundamental science involved, what we do or do not know with reasonable scientific certainty, the possible futures that await humanity and the Earth as a whole, and the choices before us. This chapter is meant to do that.