so if cities want to be sustainable and not degenerate into an urban sarlac pit after a generation then they have to concern themselves with issues of sustainability as it turns out sustainability presents some pretty hefty challenges so I reckon we ought to talk about it and if you're ready to get them brain cows milked let's get to it okay now I'm a realist and I'm going to wager that you don't remember everything you learned in unit 6 topic 8 so let me remind you of two key Concepts that create the context for the following discussion first of all remember that sustainability is a major concern for cities and by definition sustainability refers to using resources necessary to create a livable Urban Society in a way that those resources continue to be available for future generations and you know not become a stanky sarlac pit anyway tightly tied to the idea of urban sustainability is the size of a city's ecological footprint which refers to the amount of land required to support a given population's use of natural resources and so there's a direct relationship between the size of a city and its ecological footprint the larger it becomes the more resources it requires and the more strain it puts on the natural environment because you know job of the Hut didn't always need to eat that many Cline Patty frogs but you know as he uh expanded his appetite grew sorry I guess Urban sustainability issues are failed right next to Star Wars in my brain anyway the point is as the ecological Footprints of cities grow that present significant challenges to sustainability and I reckon we ought to talk about some examples but before I do if your AP exams got your feeling likee Luke Skywalker on deoa and he just can't seem to master the force then let me bring a little Yoda to your life check out my AP Human Geography heimler review guide which has everything you need to study for your class exams and that National exam in May as fast as possible you can find that link down in the description okay now let's get into some specific examples of problems that challenge Urban sustainability and I'm in the mood to give you four and these four also happen to be required so you know that's nice anyway the first issue you need to know is the problem of suburban spraw now we talked about this phenomenon in the previous unit but by way of reminder sprawl refers to the geographic expansion of an urban area with little to no planning and don't forget why this happens like according to bid rent Theory land is cheaper the further you move away from the city center but all things being equal it's not that easy to pick up and move 20 or 30 Mi away from the city unless you have easy transportation to get you there so as transportation technology has developed including the widespread adoption of automobiles and the creation of Interstate Highway systems that has become much easier to move to the Suburban surroundings of a city and so that can present a problem because as the city's ecological footprint grows so does its demand for more natural resources like food but here's the problem in many cases all that land in the suburbs where people are building their single family homes was once Farmland which is to say where all the food comes from so if left unchecked sprawl can threaten Urban sustainability by removing large swats of Farmland from production okay the second problem with sustainability is the need for good sanitation in urban areas and the two major sanitation issues in cities come in the form of garbage and you know people's nasty I mean before Modern Sanitation people just threw the contents of their chamber pots out the window done and done but that created issues of to use the scientific term stank but modern cities have more or less addressed the stank problems in various ways but as we've learned by now it's different depending on where in the world we are in core countries disposal of waste and garbage is a given and highly efficient you just put your trash on the street and some guy in a jumpsuit comes and picks it up additionally many cities and core countries have sanitation infrastructure like indoor plumbing and sewers but on the other hand in many semi- peripheral and peripheral cities there are little to no amenities to remove waste and so much of it is dumped in rivers or ditches which in turn degrades the natural environment because cities produce far more garbage because of their population densities this has become an increasing environmental concern and then the third challenge to Urban sustainability is uh duh climate change I mean most people everywhere are concerned about this but as the global average temperature continues to rise cities are the main area of concern and that's because cities produce an enormous amount of heat not only because of the high volumes of traffic but also because most urban areas are made up of hard flat surfaces like roads and concrete which radiate heat back into the atmosphere additionally when it rains water is diverted into underground plumbing which reduces evaporation and creates even more heat if you want a way to visualize that and I know that you do then have a look at what's known as an urban heat gra this line indicates temperature and you can see that the regional heat out put in a given area spikes above downtown areas and reduces significantly the further we get from the center and as long as cities continue to expand their built environment Rising temperatures are going to threaten sustainability efforts and finally the fourth challenge to sustainability is air and water quality in peripheral countries that are experiencing rapid Urban growth the infrastructure to supply everyone with clean water is lagging far behind the population numbers additionally in many of those same places the water that is available can often be polluted due to lack of adequate sanitation and then another major problem for cities in terms of air quality is smog which is a thick cloud of air pollution that gathers over a city and is made up of industrial emissions car exhaust and other pollutant and so for cities with smog issues health problems like asthma are becoming increasingly common for example behold the smog in Beijing China I'm not even sure I need to Flap my mouth hole about why this reality might be unhealthy for its residents like they're breathing that every day okay so now let's shed all the catastrophizing for a minute and look at four the solutions that City authorities have implemented in order to address these challenges first city officials have spearheaded Regional planning efforts so because cities stretch across multiple boundaries of local and City governments Regional coordination to address these challenges is essential now you may remember from the last video that multi-level coordination by various governments whose jurisdictions includes an urban area is pretty difficult to achieve lots of politicians each with their own interest fighting over scarce resources and yes that's true but there have been some shining examples here of regional planning efforts that have bolstered the cause of urban sustainability for example various Regional authorities in Amsterdam Netherlands have collaborated to create efficient mass transport and firm boundaries to contain unplanned spraw or another example in 2010 the Twin Cities region of Minnesota elected a council to oversee future Development Across the entire metropolitan area as a result land use laws were created that dictate where housing can be built so that natural resources are sustained additionally Urban infilling was emphasized as was the protection of the city's groundwater Supply okay now as important as Regional cooperation is there are still solutions that must happen on the local level so the second sustainability initiative to know is the remediation and Redevelopment of brownfields now a Brownfield refers to an abandon an industrial site and cities and suburbs that are polluted and unusable therefore many cities have passed ordinances to remediate or fix these sites which means that they remove the pollution and contaminant from the land which makes it usable for development and transforming Brown Fields has been shown to promote growth in cities as well as to revitalize zones of Abandonment a good example of this kind of transformation occurred on the par peninsula in France this was an industrial site for a long time but gradually fell into disrepair so the authorities decontaminated the soil and water and eventually transformed this brown field into a new district for the city center another example in Atlanta Georgia where former Brownfield areas have been remediated and turned into part of the city's belt line that includes walking and bike path okay a third response to issues of urban sustainability is the establishment of urban growth boundaries and often these boundaries take the form of green belts which you'll recall is a large ring of trees that surround urban areas and because of zoning laws nothing can be built on that land and that makes it a real nice boundary for checking Urban spraw now policies like this have been way more embraced in European countries than in the United States but Portland Oregon is a shining example in the US authorities there successfully used its Green Belt to limit the growth of the city which has forced Builders to renew and Revitalize portions of the city within the boundary instead of spreading outward however on the downside this practice has increased housing cost within the boundary as land and housing become even more scarce and finally the fourth response you need to know is the rise of Farmland protection policies enacted by various governments now remember that as sprawl occurs the tendency is to convert agricultural land into Suburban residential land and that's a rough situation in the long run because you know we need farm land in order to eat and so in order to combat this the US Congress for example has passed the Farmland protection policy which makes it impossible for developers to develop agricultural land without first going through a rigorous process for determining the ecological impact of that development and so let all the hungry mouth holds Rejoice okay that's the end of unit six a click here if you need to study other topics in this unit and click here to grab my AP Human Geography himler review guide if you want me to be your study Yoda and oblige you I will I'll catch you on the flipflop himler out