Personally, I do not believe that someone can create a "Perfectly Sustainable City," as there are too many factors that get in the way. Of course, some cities can be more sustainable than another. All of the other posts on this page have the same exact ideas: "Fewer cars, more bikes, more solar panels, more recycling," and that's pretty much it. While of course these do help to make a more sustainable city, there are hundreds if not thousands of other factors including ones that influence the four stated in this discussion board. For example, a few people posted something saying that we should no longer have our sewage flow into large bodies of water. The only problem is, where else are we supposed to put it? We could always just dump it in Mississippi somewhere, as it won't make the place any less desirable. Or should we burn it, and release thousands of tons of greenhouse gasses? Many of the ideas stated in this discussion board are already a reality in many places. Concerning the topic of "more electric cars," the United States cannot force companies to produce electr ic cars, and even if they could, they cannot force people to buy those electric in place of their gas car. Maybe in the future, that will be a thing, but right now, a 100% self-sustaining city is not possible.

I agree with you in terms of a city not being fully sustainable today. In a city, there will always be excess, unwanted materials. Since there is no current way of disposing these materials without harming the atmosphere or other ecosystems, the city would not be sustainable. Although, you still have the option of reusing many of these unwanted materials. I am aware that not all trash is reusable, but it would definitely make a difference. Also, with technology rapidly advancing, there could very well be a sustainable city in the future. There could one day be ways to dispose of trash that have no negative effects. However, that does not change the cities right now. Since humans do not all agree, they will never all buy electric cars, always recycle, and stop working at factories; just like you said. Time and innovation will just have to move on and hope that by the time a sustainable city is a possibility, Earth will not already be too damaged.

if the entire city is solar powered, and everything (except food which is biodegradable) is made of metal and re used by people in the city, and the city is a "closed system", than it can be fully sustainable.

I think this question is ultimately affected by the individuals definition of "perfectly sustainable." Although I believe that many cities need to move towards more renewable resources for electricity as well as decrease carbon emissions, the hypothetical idea of a perfectly sustainable city is not possible. Even with all locally raised food, depending on the city size there would not be high enough yield of crops to feed everyone.

I feel that many have come close but a perfect sustainable city is not possible at the moment. You will always have some waste no matter how much solar, wind, water, and other sources of sustainable energy you use. The key to making the perfect sustainable city is harnessing the power of the water, carbon, nitrogen, and other cycles. Once you have a way for each form to change to the other without creating any waste, you will have your city. However this is very difficult if not impossible and would cost much more than it would make to build and maintained. So my answer is no, during these times you cannot build a fully sustainable city though many have come very close.

I think the idea of a "perfect sustainable city" is very far fetched and to be honest quit impossible. But us imagining them and trying to create models of them can help us with new ideas on how we can take steps into that dream. It will never work, like someone else stated their are to many factors, and to many different ideas to consider. I think we can make really good improvements, and try to be perfect. But I think there are a lot of semantics that would have to go into it, and simply not everything would/could work. But having the idea and dream of a called "perfect" society can help us take steps into that direction.

I think we can not have a "perfect sustainable city", there are way too many gases and waste in an ecosystem that are going to be hard to get rid of. When we throw away our garbage in rather compost or recycle, some of the garbage we throw away isn't always going to be able to recycle or compost most of it will have to go to landfill but that would have our ecosystem which would cause our "perfect sustainable city" to fall apart. There are way too many factors that play into trying to make the perfect sustainable city. People would be to lazy to try and help our ecosystem an example would be at my friends house when he put everything but paper in the garbage and just but papers in recycle.

I think that it is not a possibility to create a completely sustainable city.  If we put a lot of work, money, and time into building a new city from nothing, it still could not work. I agree with Jayden when he says that the green house gasses are too important to abandon. If the city were to be made the energy sources would need to be entirely green. Meaning it would come from entirely solar panels, windmills, water mills, and other water and wind based technology. There is too much dependability on the reusable energy that is not as reliable as the greenhouses gasses that we use in cities today.

@Spencer M: Colin Y made a very good point that the cost of creating a perfectly sustainable city including all of the aspects you named in your argument. Jayden D also made a good point by saying that people are just too lazy to get used to a new way of life.

I don't think it will ever be possible to have a 100% sustainable environment because even electric cars have to be manufactured somehow and the batteries need to be charged. If you were just referring to one city, that may be possible but I think it would be more of a stunt than a new lifestyle.

I do think that we can have an environmentally sustainable city because of look at us now- living in an environmentally sustainable world! (If we weren't putting all of that carbon dioxide in, that is). With advances in technology that will undoubtedly come, scientists believe that we will have a city that will be able to support itself within the next hundred years or so. I understand that there are a lot of factors to control and regulate and that it will take a ridiculous amount of resources to undertake this feat, but humans have proved themselves to be a very resourceful species. A few hundred years ago, who would've believed that the common man could be in the sky zipping over the great expanse of ocean and earth? Yes, humans will have to adapt to very different and somewhat limited lifestyles, but I know that if there was a way to live in a place that didn't harm the earth and where I and my kids could live forever, I wouldn't think twice about it.

I agree that no city can be perfectly sustainable, but actions can be taken in every city to make it more environmentally friendly and reduce their carbon footprints. Like you said, things like recycling programs and car reduction/more bikes can help in this regard. I think other ways that cities can work towards achieving a lower carbon footprint and higher levels of sustainability would be more spare the air days, funding towards public transportation like buses and ferries, beach clean up days, and widespread recycling and compost bins in all areas. These actions would reduce waste on the land and the pollution in the air, making cities cleaner, healthier, and able to support generations to come.