Which shortages are you talking about? Oil? Food? Please elaborate.
Fuel resources, fresh water, various kinds of foods, arable land, material resources. We are already seeing various conflicts about land, water, and fuel.
Escalation of wars? What escalation of wars? There's been a steady pace of wars since history was first written down! I understand that war is now the popular thing because of Iraq and Darfur, but conflict between humans have always been there. While I can't claim to be a historian, I'm pretty sure there's always been a war going on somewhere.
If anything, I'd say wars have declined in the past few centuries.
Everyone pictures wars in the past as being these amazingly large things... yet most of the entire wars in human history were smaller than one single battle of WWI. That is both in terms of destructive power and number of people. WWII dwarfed WWI in all respects. Wars used to be about armies confronting one another and perhaps sieging stragegic towns or strongholds. With industrialization those bastions were no more and instead wars became about controlling or destroying resources (including human populations and morale). Thus wars have turned to carpet bombing cities, wiping out massive civilian populations (something that really did not happen very frequently earlier in history- now it is the rule instead of the exception.), and the deprivation of natural cover and resources to the enemy (aka napalm in vietnam). We have seen non-stop warfare in many parts of the world of late. As humanity grows ever more dense in numbers, people have ever more reason to fight over what they have always fought over- religion, land, resources, pride, etc.
From Korea to Vietnam, WWI, WWII, Iraq part one, Iraq part two, Iraq's invasion of Iran, The Yom Kippur War, The Seven Days War, Afghanistan (Russia), Afghanistan (US), the Balkans, god knows how many african wars... I really can keep going if you want, but those are just the ones I can name off the top of my head. Those are wars in just the last few decades really, with WWI being much older of a conflict than all the rest. Here is a list of what the UN defines as the current major wars going on right now. These are conflicts with greater than 1000 battlefield deaths per year. You will note that the list is around 40 conflicts long.
Link
While I agree we are destroying environments and causing certain animals to go extinct, I don't feel this is directly related to over population. You could probably cut the world's population in half and still have these problems.
As humanity grows in population it expands into the habitats of animals and plants. Those are displaced (read as killed/burned/cut down/forced elsewhere). Human expansion is the
primary cause of habitat loss today. Those directly result in massive pressures upon the species which causes them to be extremely vulnerable to extinction. Furthermore many of the "domesticated" areas of the world like the entire east coast of the US and most of Europe are not really compex ecosystems anymore. They are incredibly simplified since the entire areas were deforested and replanted with easy to manage species. These are not healthy ecosytems, these are bare-minimum ecosystems which cause populations (like deer) to go completely out of whack. They also present vast opportunities for invasive species to take hold which futher cause problems for the natives.
I think this is more "History repeating Itself" rather than a sign of too many humans on the planet.
Looking back at Europe in the 1340's, I'm sure the Bubonic plague looked like the end of the world too. It killed over 75 million people in less than 60 years. Yet now we look back at it with a vaccine and understanding on how it happened and why. While I'm only speculating, I wouldn't be surprised to find us looking back at AIDS and cancer the same way in a few decades.
Today due to the sheer complexity of all the chemicals, medicines, pollutants, etc we use and are exposed to, we have vast quantities of allergies, illnesses, and other disorders that never existed before. Look at the statistics on mental disorders such as autism and respitory disorders such as asthma, and you see that these were extremely rare... and are now basically running rampant. AIDS and such are the least of it, we are managing to weaken our entire gene pool. Modern medicine actually weakens the gene pool because it allows people who normally would have died/ been unfit to pass on their genes to their children. We are working on "solutions" to this problem with gene therapy and such, however there is a strong body of evidence that the more we mess around the more issues we cause in solving the old issues. These merely make us more vulnerable to other problems, I don't see them being one of the leading causes of a population crash.
So... Your saying eventually all forms of government and society are going to break under the increasing amounts of opinions? Of course they are, and it's been happening for thousands of years... It's just not causing the end of the world. People have always been disagreeing about something. It doesn't really matter if you have two views or two million views. People will argue.
We cannot fathom how much more complicated things are today than they used to be. Billions of ideas meshing, thousands of new technologies springing up and interacting each year, social organisation getting rewritten every time a new mass communication method is invented. For most of human history, control was localized and government was by necessity based on a relatively small region. Governments like the Roman Empire defied this trend for a time, but they also were not dealing with vast technological and societal improvements/changes and having to revise their legal systems every other year to keep up. We probably pass more laws every few years than they had on the books. And it's to the point that no one can keep track of it all, so it (like as you said bureaucracies always have done) spiral into an endless loop of unbreakable complexity, power-scheming, and inefficiency. But if that happened and caused downfalls of governments in the past, how much worse when you amplify the bureaucracy by 1000? And consider that it's not just more opinions, it's billions more opinions and growing extremely fast. Most of human history was marked by real change occuring over generations, now it occurs in months. Technological advancement, ethics, and governmental rule are not keeping pace with one another. Technology and population are rushing ahead so fast that ethical codes and governmental strategies are being left in the dust. Consider that the US constitution was drafted to provide the rule of law for about 4 million people. Do you really think our systems are so perfect that they can scale efficiently from 5 million to 300 million? To say nothing of the constant need to revise infrastructure? (some of which is starting to fail in pretty drastic ways because it simply cannot keep up).
Link to map and rate of human population growth
But will that constant arguing cause the end of civilization? I don't really think so, because the entire human race isn't a bottled up 3rd world country in chains. While I'm sure there are some people willing to go to that extent of collapsing goverments, most of the world is educated enough to know life is about compromises.
Life is about compromises but people rarely want to compromise. People are not by their very natures entirely rational beings. It makes finding and working out practical solutions increasingly difficult. As a prime example, the US recently passed a measure saying that we will in the near future set up a conference or whatnot to pass a measure to address climate change. That was hailed as progress. Nothing was accomplished and it will probably come to naught, yet it occupied weeks of the legislature's time and focus.
"Those who do not learn from their History are doomed to repeat it."
I feel that today's society is above a total collapse. (Granted it would be pretty awesome to see a total collapse.)
I think a collapse would be one of the most aweful things I could witness. I also agree that we wouldn't have a total collapse. However even a partial one is enough to send us spiraling down into a place we really do not want to be. Imagine a collapse of the asian nations. Billions of people starving/rioting/scrabbling for power. And that's just one continent. Throw in the tools of modern warfare and you have a very seriously sick situation that wouldn't leave anyone unaffected, even on the other side of the world.
Also, remember that we don't need a total collapse to bring us back below that population threshold. Many species suffer partial collapses and some even develop a perfect sin wave with the resources that sustain them. They constantly rise and crash, rise and crash following the restoration of that which provides them with life.