Economists, development experts, and world leaders have long warned that climate change is likely to hurt poor countries more than rich ones. Recovering from disasters like hurricanes or floods or drought is more challenging when resources are thin, and extra heat hurts more when humans and crops are already near their limits— the case for many countries in the climate-sensitive tropics. “So even without this added economic penalty, those poorer places would bear the brunt of climate change,” says the Lab's Amir Jina, an environmental policy expert at the University of Chicago. Much of the research on the social and economic impacts of climate change looked into the future, years or decades or centuries ahead. But in recent years, scientists have begun to tease out exact calculations of how much climate change has already affected us.