Answer:
decrease in sea levels
increase in vegetation
warmer global climate
Explanation:
This all helped in making human surivial easier.
Lincoln Issues the Emancipation Proclamation. One month later, after the qualified Union victory in the Battle of Antietam, Lincoln issued a preliminary proclamation warning that in all states still in rebellion on January 1, 1863, he would declare their slaves “then, thenceforward, and forever free.”
The south approved slavery because slaves were useful to them on their cotton farms. However, after the invention of cotton gin many saw that they didn’t need to slaves to work for them on the cotton fields anymore as it was easier to own a machine which would do the work instead. They saw the slaves as pointless and impractical after the invention.