At lasta global plan that actually adds up.James Hansen former director NASA Goddard Institute for Space Studies The world must reach negative greenhouse gas emissions by 2050 to avoid the most catastrophic effects of climate change. Yet no single plan has addressed the full scope of the problemuntil now. In The 100 Solution Solomon GoldsteinRosea leading millennial climate activist and a former Massachusetts state representativemakes clear what needs to happen to hit the 2050 target