Around half of the world's population lives in cities. It takes a lot of energy to grow and transport food into cities from agricultural areas. Why not transform skyscrapers into farms?
It's just one solution needed to feed our growing global population, which is expected to increase from around 6 billion today to 8.3 billion by 2030, according to the United Nations.
"The biggest problem facing us as a global species is where will the food for the next three billion people come from?" says ecologist Dickson Despommier. "So it could come from someplace other than a traditional farm and the question is, could vertical farming solve that problem?"
Today's big idea asks that question and explores some of the answers being championed by innovators of vertical farming.