The Global Average Calory of Soot

The soot from burning cities would encircle the planet and cool it by reflecting sunlight back into space. And they predict that this would cause a global crop failure, and in the worst case scenario, could put five billion people on the brink of death from starvation. The temperature of the earth could drop from anywhere between like one to 16 degrees celsius on average because this debris for years would be on a units cemprature.