Chicago, IL and Charlotte, NC. One of the biggest global opportunities we have to positively impact our carbon footprint is to plant "green roofs". Rooftops across America and the planet offer nearly untapped, limitless space to plants perennials, shrubs, even trees that can cool the air in and above our homes and offices, absorb carbon dioxide, return oxygen, reduce runoff, filter pollutants and provide habitats for birds and other wildlife. And if that weren't enough, they also provide a welcomed respite for mind and body. Green roofs are rapidly gaining popularity in commercial and residential design. From an up close and personal tour of the famous rooftop gardens at Chicago's city hall and the Lurie Garden at Millennium Park, to a demonstration of how to implement a smaller homegrown version, we'll explore the beauty, contribution and huge opportunity green roofs offer us all as we look for more great ways to Grow a Greener World. Chef Nathan uses one of the most common roof top vegetables, the tomato, to create something delicious in the GGW kitchen.