How did the Great Depression affect the world economy?
I hope you don't expect a short answer....::)
The great depression was not inevitable, and could have been just one of the many stock market crashes. The Fed created to fight the last crash but not this one, was so prepared it cut the liquidity, To prevent excessive speculation. That was an unfortunate move, one that could have taken place before the crash but after the crash it had the effect of making any rebound impossible and the economy sunk for four years, instead of a couple months.
Benjamin Strong was at the NY Fed, and being in New York, he knew what was going on, warned against drastic measures. Young knew far less, but he was in DC. He had the power. Nothing new. Young dried the market instead of trying a soft landing.
A dozen million unemployed, half the banks failed. One would have to wait for the New Deal for a recovery.