"In 1983, evidence started emerging that a major nuclear conflict could result in substantial weather changes over vast regions of the globe, including severe surface cooling over the continents. Refined projections of the density and horizontal extent of persistent layers of smoke (soot) led to revised estimates of the magnitude of the postulated surface cooling. The impact to the post-attack environment (even given the range of uncertainty due to the assumptions made) implied heretofore unrecognized consequences to the quality of life in vast regions and to effective national defense planning and execution. Subsequent studies sought to reduce the uncertainties in the calculations, by clarifying some assumptions and replacing others with more complete and newer scientific data. They have resulted today in assessments which, while indicating smaller surface temperature effects than previous studies for a given amount of soot, do document with increased scientific certainty that secondary consequences of a nuclear exchange would complicate the quality of life of survivors for extended periods and over areas well removed from the geographic region directly involved in the exchange. The resulting period of abnormal optical path lengths due to smoke (soot) would also complicate national defense contingencies. This report includes sections dealing with (a) an early diagnosis of atmospheric effects, (b) soot; properties and production, (c) atmospheric models, (d) a review of published comments and meetings and (e) potential impact on USAF operations."
Defense Technical Information Center (DTIC): http://www.dtic.mil/dtic/