 This may come as shocking news to some of you, but cities are not sustainable. Cities require more food, more water, more energy, and more of just about every other resource than they can ever hope to produce within their own boundaries. Cities that want to grow are faced with a couple of bad news items regarding food and water, the loss of agricultural land and new development, less food, or the introduction of new waste streams for more populations that will get into food and water supplies. So in order to manage this, cities have a dilemma. They either have to import vast amounts of food and water from remote locations beyond their boundaries, or they choose to do other things like create urban growth boundaries, green belts, to slow or stop growth, which leads to higher density in the center. Higher density in the center and green belts have other issues, secondary issues. The biggest secondary issue with a green belt to control growth is the driving up of housing prices, which makes cities unaffordable. We already have a problem with housing affordability in cities. Moreover, our research has shown that green belts erode over time because of development pressures, and so we need to look for an alternative. Cities can become vastly more innovative if they begin to think about how to integrate food and water waste into city form itself, rather than exporting it to a remote location. Right now, the way we think about that in the context of cities is we capture everything at the end of the system before it goes into the oceans or into further soil. One of the things that I would like to try to describe is the holistic city idea, the idea that we can do something more than just capture it at the end of the system. So let's explore that in the developed world and the developing world. In the developed world, we're never going to be able to grow enough food and water in the shadow of post-industrial sites on interstitial parcels. There's just not enough surface available. Moreover, we should ask the question, is that really what we want to do is compromise more food and water on contaminated land? I say the answer is no, we could do better. Colleagues at MIT have developed a vertical aeroponic farm model. It's called the City Farm. And the City Farm grows food in cities by attaching to building facades in a safe and controlled environment, whether there's air pollution or no air pollution. Now, it's expensive, we don't know how much that will translate to other parts of the world, but it is a model. The more common solution is to do regional agriculture within 400 miles of population centers, which leads to highly fertilized land, nutrient plumes, algal blooms, and fish kills. Also not a great solution. So what we've done is tested and designed a new kind of wetland cell, a new wetland model that's super efficient biologically. And I daresay elegant, beautiful, it's aesthetically pleasing. The idea being that using ecological processes scaled up over the course of a city, over the space of a city, that you can embed wetland models, wetland cells, to clean water using ecological process and build biological habitat at the same time. Biodiversity is down 50% globally since 1950. These can be scaled up and attached to each other, systematically linked to change over the course of a year, depending on agriculture rates, fertilizer rates, urban runoff, or even recreation needs. Now, at the metropolitan scale, I would like to introduce a new concept, what I call waste belts or water belts instead of green belts. In waste belts, you can imagine these complexes where you're grabbing waste, where you're using waste from agriculture and water resources, and you're building economic opportunities from them using new technologies. Now, in the developing world, we have a different solution. This solution is, which I'm going to show you in a second, it's called the Agribusiness City. There's going to be thousands of new cities coming online that we can rethink from scratch. We can make a huge environmental difference if we can really rethink how to use agriculture and water resources from the beginning of city design. And this is our model. This is a small piece of it. And in the Agribusiness City, and this is a city that we designed for 30,000 people in rural Ghana, the economy will be built in Africa out of agriculture. This city uses landscape components, landscape design elements, to recycle and feedback all the agriculture and water waste into the city. So through disruptive thinking, we can make cities more sustainable. We can rethink how to reuse agriculture waste and water waste. And the Holistic City model is an ambitious goal. The goal that all of you are, I would challenge to take on. And it can really change the way we think about all these new cities we're going to be building in the new urban era. Thank you.