The artificial ecosystems we call economies developed so we could gain more personal power, without having to give anything back to the rest of the natural world (and, to a growing extent, each other). Knowledge translated into tools (technology) that could enhance this power through access and processing of “raw materials” – the lives and life-blood of the biosphere – to create environments under our direct control. Social manipulation, enhanced by communications technologies, allowed people's behavior to be coordinated so these environments could continue to be built, improved, and function with minimal disruption in the service of their main goal.
Natural ecosystems were obvious templates for the artificial ones, except they had the unfortunate characteristic of diffusing the power of individuals rather than concentrating it. This characteristic was understandably left out of our creations. Several early attempts failed dramatically, and others much less so, merely harming large parts of their populations without totally self-destructing.
Associating the failures with the lack of power diffusion, some people tried to force that diffusion in alternate types of economies, but without realizing that it was a consequence rather than a cause, a consequence of a deeper aspect of ecosystems they failed to reproduce. And their economies also failed.
Eventually, technologies grew so powerful that the world was able to unite under a dominant economic model, a model that sadly still had the fatal flaw, but with a workaround that kept it from totally failing. Then the workaround began to lose its effectiveness, and the global economy began to falter. The prospect of worldwide failure, accompanied by the collapse of the entire human population, became too obvious to ignore.
Tragically, the underlying cause was known decades before.
Natural ecosystems function by using available energy to drive the transformation of non-living materials into life and back again, recycling everything, and collecting and reusing as much of the energy as possible. Life is not only a consequence of this transformation, it manages it. To do so, it must adapt to the variety of materials and energy sources available. Different forms of life (species) operate with different sets of inputs, and produce a different sets of outputs. Many interact with each other, using what the other has created as an input, and providing its output to another species. Every individual of every species has a role to play, and is rewarded with survival and the ability to reproduce for as long as it can do so. “Power” in Nature is a reward for keeping the transformation process going, not a goal in itself. If any population interferes too much with the process, by reducing the diversity of life or consuming more than it produces, it is generally punished severely, often by death; if it is the only population of a species, the species may go extinct.
Our artificial versions (economies) treat groups of people with specific skills as the equivalent of “species” and process energy, materials, and other species into people, objects, chemical compounds we can't use or that makes us sick (waste), and useless energy (entropy). These then become “outputs” that are returned to natural ecosystems, typically without regard for whether they can be processed by other species and eventually become “inputs” to our economies in useful forms.
Those economies that collapsed did so because they were unable to consistently acquire usable inputs from natural ecosystems, get rid of their waste (so its toxicity overwhelmed people), or both. Those that diffused power arbitrarily, without demanding that individuals perform their roles adequately, failed because they couldn't effectively do even the processing they were attempting.
Today's dominant economies survived this long because they could change where they got their inputs and where they sent their outputs. If one ecosystem became unusable, they could effectively move to another one. They did this, and became adept at changing their internal processing to handle a larger variety of inputs. They even learned to use several ecosystems simultaneously. This workaround was not without negative consequences: often there were people and economies dependent on those ecosystems, and they either resisted (sometimes violently, and generally unsuccessfully) or were assimilated into the dominant economy. Dealing with these consequences became a standard part of the workaround, often co-opting social institutions such as governments to do the dirty work (such as military domination).
The success of the dominant economies led to globalization, which ironically has made the workaround both harder to use and less effective. People have more political options for fighting the co-opting of their ecosystems. Economies are so dependent on each other now that what affect one, affects the others. Technology has become powerful enough for economies to affect the entire biosphere – all ecosystems simultaneously – and there's also nowhere else to go, though a few enterprising souls have their eyes on extraterrestrial sources.
The most popular approach is to fix our economic model. This can involve creating fewer outputs, and incorporating into our internal processing a way to make the outputs we do create more acceptable (or at least less toxic) to the biosphere. More efficient processing can be used to reduce the amount of inputs we use. And we're still working on changing the types of inputs we can use, such as directly processing solar energy (instead of relying on plants and increasingly scarce embodied energy from millions of years ago).
Another approach, gaining interest but far from popular, is to reconnect our civilization to the rest of Nature by finding ways to become useful partners in the ecological process again. Among the options being considered is decentralizing our population into communities that rely on, and interact in healthy ways with, local ecosystems, including revitalizing them through restoration of habitat and detoxifying our existing waste. Many of the same people who diagnosed the problem with our dominant economies argue that the critical resources (among them easily used energy, rare metals, and fresh water) that they use as inputs cannot be replaced fast enough (if ever) to avoid their demise; we can only transition to smaller, resilient communities as soon as possible to avoid catastrophic population loss. To work in the long term, this approach would require a drastic reset of our personal aspirations, from increasing power to valuable service, which may be the hardest change of all.