in 1863, the irish scientist john tindell determined that carbon dioxide and water vapor trapped morede would make it warmer. in the early 1900's, a century ago, it became clear that changes in the amount of carbon dioxide in the atmosphere might account for significant increases and decreases in the earth's average annual temperatures and that carbon dioxide released from man made sources, anthropogenic sources, primarily by the burning of coal, could contribute to those atmospheric changes. this is not new stuff. these are well-established scientific principles. let me look for a moment at the book that i talked about." our astonishing atmosphere, "published in 1955, the year i was born, more than half a century ago. for the science for everyman series. let me read." although the carbon dioxide in the atmosphere remains at a concentration of 0.3% all over the world, the amount of air has not always been the same. there have been periods in the world's history where the air became charged with more carbon dioxide than it now carries. there have also been periods when the concentratio