The ideal destination for climate refugees might be Duluth. As many as 20,000 people could move to the city in the coming decades, according to new research from Harvard scientist Jesse Keenan. The number of global climate refugees is expected to increase in the next few decades as some areas become too hot and drought or rain events grow more extreme and frequent. But Duluth is considered among the most "climate-proof" cities in the U.S. Keenan joined Climate Cast to explain.