Reducing the solar irradiance falling on Earth using structures at the Sun-Earth inner Lagrange point (L1) could decrease global warming even if all other methods prove inadequate. This solution is certainly feasible, but its scale requires long-term planning and investment. This paper explores ideas for building a swarm of spacecraft shades to provide the required sunlight reduction. Each member of this swarm autonomously measures and controls its orbit, ensuring durability of the swarm over many decades. Two possible implementations are discussed: A "small" swarm that could be launched from Earth, and a longerterm approach using material from the Moon (or asteroids), needed if greater reductions of solar irradiance are required.