There certainly has been a great deal of discussion about the climate in the past several decades. During the 1970’s there was concern over the possibility of global cooling, while more recently there has beenwidespread fear of global warming.
Everyone admits that the global climate is extremely complex. It appears that in the distant past the earth’s climate has undergone significant changes. More recently, some scientists are predicting severe consequences from a much more modest global climate change.
As scientists seek to understand any physical process they need to isolate the effect and influence of individual variables. In terms of the climate, there is a complex interaction of the sun and the earth’s atmosphere, and it is difficult to isolate the effect of individual components. The composition of the earth’s atmosphere is usually given as consisting of about 78% nitrogen, 21% oxygen, 1% argon and 0.04% (380 parts per million) carbon dioxide, plus other trace gases. It also, however, contains a significant amount of water vapor, which varies widely with atmospheric conditions.