Climatic consequences of a nuclear war...

[link to www.thebulletin.org]

Beneath the smoke, the loss of warming sunlight would produce average surface temperatures colder than any experienced in the last 1,000 years. There would be a corresponding shortening of growing seasons by up to 30 days and significant reductions in average rainfall in many areas, with a 40-percent decrease of precipitation in the Asian monsoon region. Basically, the Earth's surface would become cold, dark, and dry.