Larger consequences of the problem

Every large and developed country today at some point went through rapid urbanization and population growth.  One of the most notable cases of this was the Industrial Revolution in England in the 19th Century, which saw an explosion in population, particularly in urban areas.  Just as in China in cities like Shenzhen, many tiny rural communities grew into large cities in a matter of decades (http://webs.bcp.org).  This came with a slew of environmental problems, most notably pollution and disease.  

http://multimedialearning.org/presentations/220_TheIndustrialRevolution_world.php#img

As these industrial centers increasingly turned to coal to feed their growing energy demand, air pollution became a major health issue as there were no regulations limiting emissions.  The “smog” that plagued many European cities during this time has many similarities to the smog in Chinese cities today, and took decades to alleviate.  As late as 1952, a smog incident killed over 4,000 people in London (http://www.metoffice.gov.uk).  Since overpopulation, urbanization, and industrialization are all occurring on a much larger scale in China than in England, there are serious concerns about the possible effects of air pollution in China.

http://en.wikipedia.org/wiki/Industrial_Revolution#mediaviewer/File:BASF_Werk_Ludwigshafen_1881.JPG

Another major issue to arise from urbanization in 19th Century England was lack of sanitation and disease.  Since cities grew faster than the ability to properly plan them, there was no good system of sewage and pest-control, so disease grew rampant and cause many deaths (http://webs.bcp.org).  While this is less of a concern in modern-day China because sanitation systems and technologies are more well-known and easier to implement, it is still something to consider as many formerly-rural towns quickly grow into large cities that need careful planning.  

eia.doe.gov

There are many global consequences to this issue as well.  First of all, a growing population obviously requires greater resources, leading to more greenhouse gas emissions and less food and water availability.  Even more significant, however, is rising affluence level.  As China continues to industrialize and improve its economy, its residents will continue moving to cities and demanding more and more resources.  One of the most glaring examples of this is China’s demand for cars, which has increased exponentially over recent years (Nova, 2004).  This has vastly increased the amount of Carbon emissions released by China, leading it to pass the US to become the world’s biggest emitter of Carbon Dioxide, and thus the biggest contributor to global warming.  In addition, China’s smog and air pollution has become severe enough that it has begun spreading to other countries, in some cases reaching as far as the Western United States (Nova, 2004).  

Another global concern with overpopulation and urbanization in China is the allocation of resources.  As China’s population shifts from rural to urban, there is a greater demand for food yet less farmers to produce it, leading to a possible famine.  This could become a global phenomenon, as more and more countries follow the same trend as China and most countries are unable to export food.  This concern applies to other resources as well, particularly non-renewable energy sources such as oil and coal.