1)Market Liberals are grounded in neoclassical economics and view the main drivers of environmental degradation as poverty, lack of economic growth, and bad policies; the best way forward is more globalization, enhanced efficiency, voluntary corporate greening, and market-based incentives to encourage clean technologies. 

2) Institutionalists are informed by international relations and political science.  They also believe in economic growth and globalization, but stress the need for strong global regimes to manage the global environment, more global cooperation, and a precautionary approach (of the four views, they have the broadest base of political support). 

3) Bioenvironmentalists are based in the physical sciences, focus on ecosystems, and stress carrying capacity and the biological limits of earth.  They seek to limit population, reduce consumption, and create a new economy based on new measures of progress. 

4) Social Greens draw on radical social and economic thought, shunning large-scale industrial life, globalization, and in some instances capitalism.  They seek to restore local communities, promote ecological justice, and empower the marginalized.

These four worldviews offer a very useful framework to begin to appreciate the very different "paths to a green world." 

At the same time, Sustainability is just one of three broad ideals that are being pursued and should be pursued.  Arguably, Sustainability should overlap with both Security and Human Rights. One can also argue that little or no progress is being made in Security or Human Rights, despite huge and often misguided expenditures on the former and widespread attention to the latter.

Remarkably, these three complex ideals are virtually separate from each other.  In 2007, a 63p report by 11 retired high-end US generals and admirals, National Security and the Threat of Climate Change, warned that climate change could lead to destabilization and violence.  A more detailed report by the German Advisory Council on Global Change, Climate Change as a Security Risk (Earthscan, 2008, 248p; www.wbgu.de) identified four "conflict constellations" related to climate change, and eight regional "hotspots." However, since then, books on Security appear to be largely if not entirely silent on this long-term issue.  As for Human Rights, freedom from threats of nature's violence, as well as man-made violence, would certainly seem to be a universal right, and, as is widely known, actions taken in the name of security are often at odds with human rights to privacy, freedom of speech and assembly, and well-being.

All three ideals deserve to be pursued, and none will ever be fully and finally attained.  As Secretary of State Hillary Clinton recent noted, "most of these problems are never solved... you just keep working at them and working at them and working."

We can work at them better, perhaps, by looking broadly at the latest thinking about all three ideals.  One book that does suggest how to integrate the three ideals is 2048: Humanity's Agreement to Live Together, the final item in the Human Rights section.

To provide a quick scan of current concerns, a selection of 30 recent book titles on Security is offered here, as well as 15 books on Human Rights. 

As indicated above, Sustainability is a broad and essential concern, with many paths of action, and many individuals, companies, and governments taking actions for a "greener" world.

Nevertheless, it is quite uncertain as to whether overall progress is being made against the mounting threats of climate change, pollution, and over-consumption of finite resources due to rising demands of a growing world population. Battles may be won, but the overall war may still be worsening.