Sol Hsiang, co-director of the Climate Impact Lab, and a team of researchers at UC Berkeley, including other researchers with the Lab, recently published new research in Nature that shows that early emergency COVID-19 policy measures prevented over 500 million infections in just six countries. Sol joined Rachel Maddow on MSNBC to discuss the new research. "It's been a really difficult year and it's a little inspiring to think back and realize what it is that we achieved together by coordination, cooperation, using science. We did something that's never been done in human history, and we should be proud of that. But it's not over," said Hsiang.