Large social/political movements usually start out on the fringe of political discourse, slowing building momentum until their moment finally comes.

As 19th Century French writer Victor Hugo (author of Les Misérables and The Hunchback of Notre Dame) put it: “One withstands the invasion of armies; one does not withstand the invasion of ideas.” Often paraphrased today as: “Nothing is stronger than an idea whose time has come.”

Almost 50 years after Rachel Carson launched the modern environmental movement with the publication of her book “The Silent Spring,” we –as a society– are beginning to think seriously about what it means to be truly environmentally sustainable.

Organic food, renewable energy projects, hybrid/EV/ethanol fueled vehicles, and green buildings are sprouting up left and right. Innovative companies are rethinking how they design, manufacture, and deliver their products.

Cap-and-trade and other government programs will only add incentives to the market forces behind these  developments. Put all of these developments together, and you get closer to a sustainable society.

But what about putting them all together at once? Does the political support exist to create entire cities devoted to keeping their ecological footprints at levels that can be sustained over the long-term? There are indications that the answer is yes; although, there are several ways in which wholly sustainable communities may develop.

Through government support

The governments of China and Abu Dhabi are awash in cash and their economies have been growing fast–from exports of consumer products and oil, respectively. So these emerging powers decided to show leadership on the environmentally sustainable development front by creating the cities of Dongtan, China and Masdar, Abu Dhabi, UAE.

These are both massive projects, intent on growing to accommodate hundreds of thousands of residents. Their designs incorporate cutting edge technology to use only renewable energy, conserve water, transport people, construct a green built environment, and minimize waste. Masdar is taking its vision a step further and aspires to be a Silicon Valley-like cluster for environmentally sustainable businesses and educational institutions.

These projects have been slow to develop–Dongtan, for example, has lowered its goal of initial residents from 50,000 to 5,000, but still hopes to open in time for the 2010 World Expo in Shanghai–and are only showcases. If they are eventually completed, however, they will be massive steps toward the goal of fully sustainable cities, right in two vital organs of the developing world.

Private sector development projects

Rich governments can invest in futuristic cities that would not be economically feasible in their own right, but real estate developers have to respond to consumer demand. Firms around the world are responding to the growing demand for green buildings and sustainable communities with projects that range from single LEED certified houses to entire communities.

Bioregional, a British non-profit on the cutting edge of environmentally sustainable development, has partnered with the World Wildlife Foundation to create the One Planet Living Program (OPL). OPL Communities aim to keep resource use at a level where if every human lived as their residents do, we would only need one planet to sustain society (the average American currently lives at a 5 planet level; Europeans, 3 planets).

I find OPL to be an extremely functional definition of what environmental sustainability is all about. There are currently about 10 developments which meet the OPL criteria either under construction (including Masdar) or already built on 5 continents.

Co-housing is another way to develop a sustainable community, usually on a small-scale. The residents of these developments work together to design a community in their own image. Environmental sustainability is often a primary concern and shared value of residents.

Private developers may not have the financing to build on the scale that a national government can, but as demand for environmentally sustainable living spreads the cumulative impact of these relatively small projects will be enormous.