Medellin, a large Colombian city tucked between the Andes Mountains, has undergone an enormous transformation over the past couple of decades. Once at the heart of the drug trade, the city went from one of the most violent in the world in the late 80s to the most innovative in 2013.
About 180,000 poor people live in the city's ultra-steep hillsides, which are vulnerable to flooding and landslides. This will only get worse with climate change: Medellin and other tropical zones are likely to see longer rainy seasons, with more intense rain storms.
In 2004, the city built an aerial lift public transit system, called Metrocable, to help people who live on the hillsides go up and down the mountain. In 2011, it launched a "Metropolitan Greenbelt" — a 46-mile-wide ring of nature reserves around the city — to curb urban development.
"It's an exciting story," Cynthia Rosenzweig, a climate scientist at NASA, told BuzzFeed News. "It's a city that's really trying to turn itself around."
Rosenzweig helped write a new report on how cities are adapting to climate change, which was released on Friday at the big Paris climate talks.