Answer:
events such as World War I; the Bolshevik Revolution and the ensuing Soviet experiment; the Spanish Civil War; Nazism, World War II, and the Holocaust; the Cold War in Europe; the collapse of communism; and the Balkan Wars in the 1990s.
Step-by-step explanation:
The 20th century saw a massive transformation of the world order: global total fertility rates, sea level rise and ecological collapses increased; the resulting competition for land and dwindling resources accelerated deforestation, water depletion, and the mass extinction of many of the world's species.