Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 6 6 2006 10.5194/acpd-6-11817-2006 http://www.atmos-chem-phys-discuss.net/6/11817/2006/ http://www.atmos-chem-phys-discuss.net/6/11817/2006/acpd-6-11817-2006.html http://www.atmos-chem-phys-discuss.net/6/11817/2006/acpd-6-11817-2006.pdf 11817 11843 2006-11-22 Climatic consequences of regional nuclear conflicts A. Robock L. Oman G. L. Stenchikov O. B. Toon C. Bardeen R. P. Turco Department of Environmental Sciences, Rutgers University, New Brunswick, New Jersey, USA Department of Atmospheric and Oceanic Sciences and Laboratory for Atmospheric and Space Physics, Univ. of Colorado, Boulder, USA Department of Atmospheric and Oceanic Sciences, Univ. of California, Los Angeles, USA We use a modern climate model and new estimates of smoke generated by fires in contemporary cities to calculate the response of the climate system to a regional nuclear war between emerging third world nuclear powers using 100 Hiroshima-size bombs (less than 0.03% of the explosive yield of the current global nuclear arsenal) on cities in the subtropics. We find significant cooling and reductions of precipitation lasting years, which would impact the global food supply. The climate changes are large and long-lasting because the fuel loadings in modern cities are quite high and the subtropical solar insolation heats the resulting smoke cloud and lofts it into the high stratosphere, where removal mechanisms are slow. While the climate changes are less dramatic than found in previous "nuclear winter'' simulations of a massive nuclear exchange between the superpowers, because less smoke is emitted, the changes are more long-lasting because the older models did not adequately represent the stratospheric plume rise.