If the global climate warms, how will this affect human societies around the world? Science fiction books and movies speculate about possible futures, but what do the data say? A revolution in data science is illuminating how human societies around the world are shaped by the climate—from the happiness revealed through a New Yorker’s tweets, to rates of gang violence across Mexico, to the economic performance of entire continents. Armed with these insights, policy scientists are increasingly able to paint a clearer picture of what is likely to lie ahead for society if the climate continues to change. Solomon Hsiang, co-director of the Lab, explains research advances in this field, focusing on his recent work tracing out the effects of climate change on economic inequality, violence, and social stability around the world. By understanding how the climate influences our lives in these basic ways, this research is restructuring how we understand the implications of different climate policies.