It's erroneous to point the finger just at capitalism, though that ideology does appear to be more efficient at ecological destruction than most. I can't name one economic ideology that has operated in the last few hundred years that didn't have growth as its core assumption. Communism, socialism, capitalism (free market and regulated), even feudalism -- all bow to the god of growth.
The real problem that has wrecked the world is our underlying paradigm of infinite growth in a finite world. While capitalism is very, very good at maximizing the negative consequences of that misunderstanding of reality, there is no evidence that other systems are much better at recognizing and living within limits either. Communism of all stripes ran into
The Tragedy of the Commons in a big way, and even moderate mixed-market socialist countries like Sweden still look forward to growing their GDP every year.
Socialism might give us a chance, because to adopt it requires the fundamental realization of the interdependence of all human beings, and maybe by extension the interdependence of all living beings. However, the core dualism (man's conviction that the world consists solely of humans and resources) that has backed us into this box isn't directly addressed by political or economic socialism. Unless we could correct that dualist mis-perception in a sufficiently large number of people, there isn't an organizing principle yet invented that couldn't and wouldn't be perverted in the interests of power and status. The drive to reproduce, consume, compete and acquire status are human characteristics that are, if not actually genetic, at least deeply embedded by biological and cultural evolution. As a result they are very hard to thwart.
A reduction in human numbers and human activity (whether voluntary or, more likely, involuntary) will save more of the planet's ecosphere for other species and our own descendants. Unfortunately, the organizing principle that will be in play when that happens is far more likely to be tribal than socialist.
Our problems are well past the point where voluntary changes in human activity could prevent large-scale, traumatic changes to our industrial civilization and the people who depend on it to live. The crisis goes far beyond climate change and oil dependency, to encompass all manner of ecological degradation (the death of the oceans, soil fertility depletion, fresh water depletion etc.) and economic destabilization.
Here's my view of the situation we're in:
- There are no technical "solutions" to the converging crisis;
- The roots of the crisis are in human behaviour as mediated by our global culture and our biological makeup;
- Our behaviour will not change radically until our culture supports the change;
- Our culture will not support or even permit such change until the economic, political, educational and communications institutions that guard the central principle of eternal growth have lost their power;
- Those institutions will not lose power until their ability to function is compromised;
- Their ability to function is already being compromised by the growing crisis in energy, ecology and economics, and the increasing problems will ultimately cause failure avalanches within those institutions;
- Once the guardian institutions lose their grip, new patterns of understanding, belief and behaviour will emerge that are in line with the changing circumstances;
- These new patterns will tend towards one of two primary forms depending on the circumstances: either long term sustainability based on expanded consciousness of the web of life, or "Mad Max";
- The global movement of millions of independent, local environmental and social justice groups means that it's possible we will see enough changes toward sustainability to enable the eventual regrowth of a more humane civilization;
- Like all else in human history no particular outcome is guaranteed.
For a more thorough explanation of this perspective, see the article
Cultural Change at the Limits to Growth.