Humanity has always faced threats to its global survival, such as asteroid impacts and supervolcanoes. Yet now the greatest risks we face may be a result of our own scientific and civilizational progress. We are developing technologies of unprecedented power, such as nuclear weapons and engineered organisms. We are also wiping out species, changing the climate, and burning through the earth’s resources at an unsustainable rate as the global population soars. However, the coming century’s breakthroughs in science and technology will also provide powerful solutions to many of the greatest challenges we face.