All things come to an end

In the post on Pat Tillman below Ralph of NewsFare wrote the following in the comments section:

In many respects our republic, as it has existed since the presidency of Franklin Roosevelt, is already dead. But such deaths of governments happen periodically in most countries, I think. Now, although the outer trappings of government may not change in any significant way, we are living in an entirely different form of government than we knew in, say, the 1960s. And for us, since the changes to date appear all to have been uniformly negative, this is a very sad time.

Nevertheless, I've personally concluded it's useless to pretend we can bring back the republic we have known. Rather, we need to focus on what form of government comes next for our country. While the death of the previous republic is an established fact, the future form of our government appears to be very much in doubt, open for ideas and actions. On that, we can hope to have an influence.

Ralph of course is right but I think it goes a lot deeper than the decline of the US Republic. Like the people that create them civilizations are born, live and die. They usually don't die of old age but of some terminal disease. Our current civilization has three such diseases and no, I'm not talking about Islamic jihads. The three are:

1. Peak Oil
2. Global Climate Change
3. Shortage of potable water

Peak Oil
I first discussed Peak Oil over three years ago in Oil, Half Way To Empty. For details you can head over to that post but to summarize Peak Oil is when half of the available oil has been taken from from the ground. When that point has been reached the availability of oil will decline. This is in a world that is dependent on oil and where demand is rising. There are no alternatives that will allow us maintain our current lifestyles or even our population levels. As a result we will continue to burn oil until it is gone. And when it's gone - well the party is over.
Climate Change
Our civilization has grown and developed during a time of unusual climate stability and predictability. For whatever reason that is changing. It really doesn't matter what the cause is. If it is indeed the result of burning fossil fuels it's too late to undo the damage and as I said above we won't anyway. The results of climate change will be severe. Much of the land where people now live will become uninhabitable. It will be drought in some areas, frequent severe storms in others. And of course there will be a rise in sea level. Mush of the worlds population lives below 100 feet above sea level. Major centers of our civilization will disappear below the seas - think NYC, Washington DC, London and the list goes on.
Shortage of potable water
This may be even more critical than oil. The shortage is driven by two things, climate change and the fact that there are just too many people.

War
Of course the decline and fall of civilization will probably occur even faster as the result of wars fought over declining resources. We are already seeing this of course - every war fought in the middle east since 1920 has really been about oil. The was in Iraq is just the latest example. And yes there will be wars fought over water. And yes there will be wars fought over real estate as once habitable lands become uninhabitable.