"Attached for your information and guidance is briefing material on the CO2 'Greenhouse' Effect which is receiving increased attention in both the scientific and popular press as an emerging environmental issue....The material has been given wide circulation to Exxon management and is intended to familiarize Exxon personnel with the subject. It may be used as a basis for discussing the issue with outsiders as may be appropriate. However, it should be restricted to Exxon personnel and not distributed externally.... Predictions of the climatological impact of a carbon dioxide induced "greenhouse effect" draw upon various mathematical models to gauge the temperature increase. The scientific community generally discussed the impact in terms of doubling of the current carbon dioxide content in order to get beyond the noise level of the data. We estimate doubling could occur around the year 2090 based upon fossil fuel requirements projected in Exxon's long range energy outlook. The question of which predictions and which models best simulate a carbon dioxide-induced climate change is still being debated by the scientific community. Our best estimate is that doubling of the current concentration could increase average global temperature by about 1.3 to 3.1 degrees Centigrade. The increase would not be uniform over the earth's surface with the polar caps likely to see temperature increases on the order of 10 degrees Centigrade and the equator little, if any, increase.... The state-of-the-art in climate modelling allows only gross global zoning while some of the expected results from temperature increases of the magnitude indicated are quite dramatic. For example, areas that were deserts 4,000 to 8,000 years ago in the Altithermal period (when the global average temperature was some 2 degrees Centigrade higher than present), may in due time return to deserts. Conversely, some areas which are deserts now were formerly agricultural regions. It is postulated that part of the Sahara Desert in Africa was quite - wet 2,000 to 8,000 years ago. The American Midwest, on the other band, was much drier, and it is projected that the Midwest would again become drier should there be a temperature increase of the magnitude postulated for a doubling of atmospheric CO2. In addition to the effects of climate on global agriculture, there are some potentially catastrophe events that must be considered. For example, if the Antarctic ice sheet which is anchored on land should melt, then this could cause e rise in sea level on the order of 5 meters. Such a rise would cause flooding on much of the U.S. East Coast, including the state of Florida and Washington, D.C.... The greenhouse effect ls not likely to cause substantial climactic changes until the average global temperature rises at least 1 degree Centigrade above today's levels. This could occur in the second to third quarter of the next century. However, there is concern among some scientific groups that once the effects are measurable, they might not be reversible and little could be done to correct the situation in the short term. Therefore, a number of environmental groups are calling for action now to prevent an undesirable future situation from developing. Mitigation of the "greenhouse effect" would require major reductions in fossil fuel combustion."