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Peru's Ancient Stone Canals Peru's capital Lima is the second-largest desert city in the world. Although the region enjoys a surplus of water during the rainy season, keeping it is a problem. The excess often ends up back in the ocean, leaving Lima's nine million residents without a regular water supply during the dry winter months. But a network of stone canals dating back to the seventh century could be a solution to the city's water crisis. Situated in the highlands of the Peruvian Andes, these canals were an effective method of storing water during the rainy season. As the bottom of the canals are porous, the water filters directly into the ground and runs into springs and natural reservoirs further down the mountain, maintaining river flow during the dry season. Having fallen into disrepair, they are now being restored with the support of local NGOs. Juliana Schatz travels to Peru to speak to those living with severe water shortages and visits the Andean community of Huamantanga to see how restoring the ancient canals could help supply running water for millions of people living today. Japan's Future Farms By 2050, the world will need to feed an additional 2.5 billion people living in cities. Yet as the demand for food rises, the amount of land available for agriculture in developed countries is expected to decline. In Japan, at the Fujitsu factory of Aizu-Wakamatsu which still manufactures semiconductor chips for computers, a different project is underway which may offer a solution to this problem. The company has converted an unused part of the factory into a farm to grow food - and more specifically, to grow lettuce. Fujitsu has focused on growing a low-potassium variety, which is sold to people with kidney problems who cannot process the mineral properly. Join Rachel Mealey in Japan's Fukushima Prefecture to visit the sun-free and soil-free urban farms of the future. Cryocoral Conservation Coral reefs are the most biologically diverse marine habitats in the world. As well as providing vital protection against storm damage and coastal erosion, millions of people rely on reefs for food. Yet years of unsustainable fishing practices, pollution and rising sea temperatures means that up to one-fifth of all coral reefs around the world have already been destroyed. So the battle is on to safeguard their future. Dr Mary Hagedorn of the Smithsonian Conservation Biology Institute has been on a global mission to create a seed bank to protect the world's highly-threatened coral biodiversity. Using technology and techniques similar to those used in human sperm banks, Hagedorn and her colleagues were the first on the planet to cryogenically freeze the sperm and stem cells of coral. Russell Beard travels to Oahu, Hawaii, to join Dr Hagedorn's team on a spawn gathering trip to gather and freeze endangered coral sperm and cells for future use.