One reason: Plowing large areas of land
A few more reasons: poor farming practices, farmers would loosen up the soil, and the land was deforested, making it loose the roots that held the soil in place.
Answer:
Kennedy worried that actions on the part of the United States might start a war with the Soviets.
Explanation:
The Cold War was a difficult period in human history, which every action could lead to a physical conflict. All the diplomacy would be taken carefully. The Berlin Wall was an East German initiative that was under Soviet control. Because of that, Kennedy was afraid that his actions were seen as a threat to the Soviet government, leading to a real conflict.
black death was the name of the horrible disease hit Asia Africa and Europe in the 1300s