• Solutions to the biggest threats facing our planet lie underground, according to experts who insist climate change, overpopulation and food shortages can all be tackled by going subterranean.
• Efforts to meet seven of the United Nations’ 17 sustainable development goals — from cleaning up pollution-clogged metropolises to ending world hunger — could be given a big boost by re-purposing spaces below street level.
• Scientific developments in areas like aquaponics — where vegetables and fish are farmed together — could help relieve the pressure on the food supply chain, and dramatically cut transport costs if such new farms were situated under cities.