The 21st century is argued to be the most important century in human history due to rapid technological growth and the potential for transformative technologies like artificial intelligence. However, this century also brings unprecedented levels of existential risk, including the possibility of nuclear winter, climate change, and pandemics. The emergence of artificial general intelligence (AGI) poses further risks, as the values and impact of AGIs on humanity are uncertain and could lead to value lock-in, constraining moral growth. The future is highly uncertain, but the decisions made in this century could have a major impact on humanity's future.