List of future astronomical events. List of 21st-century lunar eclipses; List of solar eclipses in the 21st century; Projections of population growth; Climate change. Representative Concentration Pathway; Shared Socioeconomic Pathways; Extinction; List of dates predicted for apocalyptic events; Predictions and claims for the Second Coming of Christ
The 20th (twentieth) century began on January 1, 1901 (), and ended on December 31, 2000 (). The 20th century was dominated by significant events that defined the modern era: Spanish flu pandemic, World War I and World War II, nuclear weapons, nuclear power and space exploration, nationalism and decolonization, technological advances, and the Cold War and post-Cold War conflicts.