"Great things are done when men and mountains meet" - William Blake
Joseph Tainter, an archeologist, produced an extremely insightful book entitled The Collapse of Complex Societies [Book Link], which analyzes the collapse of historical human societies in terms of increasing complexity and diminishing returns to complexity. For those who don't have the money or time to read the book, here is an interview he recently did with Jim Puplava at Financial Sense Newshour where he summarized the intriguing ideas presented in the book [FSN Interview]. The following paragraphs will explore a key relationship between complex human society and the complex atmospheric and ecosystems of our planet.
Tainter makes the point that all collapses in human societies have been triggered by declining supplies of stored solar energy and therefore the ability to maintain complexity through economic growth and central regulation/management. He effectively places all of human civilization under the dynamics of this process involving increasing net energy and complexity, maintenance of complexity through additional energy inputs and regulation, diminishing returns to complexity and decreasing net energy, and eventually rapid collapse and simplification. Those people familiar with Buzz Holling's fractal adaptive cycles in ecosystems, or who have read my essay "The Limits to Complexity" [Essay], will immediately see how this process reflects the first three phases of growth, conservation and release. I also believe the above dynamic can be viewed as one present in systems even larger than human societies, including our planetary's atmospheric system and biological ecosystems.
The Roman Empire increased their net energy returns by using military force to overtake various regions and turn them into imperial territories. These territories contained food stocks and various commodities that represented a surplus of stored solar energy which could be extracted and directed towards central regions of the Empire. It is pretty clear that we have done the same thing through expansion of the American Empire, except our extracted deposits of stored solar energy are in the form of fossil fuels which were developed over millions of years.  In the 1940s, the net energy obtained from a unit of extracted crude oil was about 99 additional units, which obviously allowed our global empire to achieve a level of complexity never witnessed before in human history (now it's closer to 10-20:1 for most sources). This great expansion can be viewed as our growth phase, but we should also take the time to view this process from the perspective of our planetary system.
The Earth took a great deal of time to create a stable climate that would be conducive to growing ecosystems and increasing complexity. A major part of this process was extracting carbon dioxide dispersed throughout the atmosphere and concentrating large chunks of it in somewhat centralized deposits underneath the Earth's surface. Since the beginning of the fossil fuel age, humans have been liberating these stored deposits into our industrial economy, which in turn returns the carbon into the atmosphere. In this sense, the burning of fossil fuels during our growth phase has been an ongoing process within the preliminary release phase of our atmospheric system. It may seem counter-intuitive that millions of years of stored solar energy could be liberated within several hundred years, but the technology we developed via our energy inheritance has allowed this rapid liberation to occur. It is also true that we most likely will not be able to release all of the stored fossil fuels (if even much more than half), since our technological and financial capacities are reaching their limits to extract what's left of the oil and coal in the Earth.
The effects of release within our atmospheric system are already beginning to destabilize climate conditions around the world, and therefore weather patterns and many other natural processes within ecosystems. However, our planet's richly complex atmospheric and biological ecosystems have evolved over many years with a certain amount of redunancy and resilience in the face of destabilizing events. The full process of release will not be something that happens within ten, twenty or a hundred years, and many biological ecosystems will retain a significant level of complexity for some time. What is clear, however, is that the effects of climate change are already imposing significant social, economic and physical costs on human systems of organization that represent the tip of our planet's pyramidal structure of complex systems. There is also scientific evidence that suggests we are rapidly approaching a tipping point in climate change, after which the destabilizing effects of carbon emissions will enter an irreversible self-reinforcing process that will increase global temperatues and prove extremely destructive for many different biological systems .
The good news, if one can call it that, is that there may still be time left for the process of atmospheric release to stop before it leads to a complete break down in the complexity of biological ecosystems. Larger environmental and biological systems may be able to absorb much of the present atmospheric release and quickly regenerate more stable climate conditions. Perhaps humanity's lack of access to stored fossil fuels in the near future will aid in this goal, since the amount of carbon we release into the atmosphere will be greatly reduced. However, there is little room for error here, especially for a majority of human beings alive or soon to be alive, so we cannot entirely rely on peak oil to halt the process. A better idea would be to devote significant financial resources to developing and implementing clean sources of energy, while also encouraging energy efficient practices at individual, corporate and governmental scales. Will the above policies be implemented through top-down policies by centralized institutions of governance above the community level? Not very likely. Can individual agents of our complex systems enact policies of energy resilience that could potentially reach a critical threshold which prevents irreversible climate change? Most certainly. Indeed, great things are done when (wo)men and mountains meet.