Sustainability is the capacity to endure, and the capacity for humanity to endure is being tested on a global scale.

Population is exploding and becoming increasingly urbanized. It took more than 10,000 generations for the planet to reach two billion humans in the middle of the last century. But someone born at the end of World War II has already seen the population grow to 6.6 billion. If that person lives to be 100 and the pace of urbanization continues, the population is expected to be 9 billion at that person’s death.

The challenges of climate change, peak oil, clean air and water, economic redevelopment, social equity, and the many others that confront government leaders will not go away because we meant well. To do well, a plan of sustained action, based on some guiding principles, is required.

If there is good news on the sustainability front, it is that myriad efforts are under way at the grassroots level to make a difference. Observations from hundreds of sustainability initiatives around the world suggest that here are some common principles guiding sustainability improvements in the urban context.

From these common principles of urban sustainability, municipal leaders might, in turn, craft effective strategic planning processes that lay the groundwork for creating more sustainable communities. While not radically different from other interpretations of sustainability, the common themes of urban sustainability practices around the world are, essentially, fourfold: efficiency, diversity, connectivity, and restoration.

Efficiency

A sustainable community is an efficient community. Although the transfer of natural resources to population centers has underpinned the rise of communities through history, today and into the future energy efficiency will be one of the hallmarks of sustainable cities and regions. Resource- and cost-efficient energy will take many forms.

Local government leadership in energy audits, facility retrofits, and more energy-efficient building codes is a fundamental necessity, as is leadership in adopting and promoting energy efficiency standards and practices. Another fundamental necessity is a significant reduction of vehicle miles traveled; this can be accomplished through mixed use, human-scale planning and redevelopment bolstered by investments in multimodal transit suitable for regional transportation efficiency.

Diversity

A sustainable city is a diverse city. Diversity in all forms is required. Energy production must become diverse, with decreasing reliance on fossil fuels. Land uses must be diverse to accommodate the needs of daily life without wasteful transportation and to facilitate the full range of life choices necessary for community vitality.

Diversity of thought and experience in the body politic is significantly important for a community to consider alternatives and choose optimal outcomes. The basic economy of a community must be diverse enough to weather financial storms in any one sector. Consequently, educational opportunities must be diverse, robust, and lifelong in any place that desires to be sustainable.

Connectivity

A sustainable municipality is a connected one. Here again, energy is significant. The manner in which energy production is connected to local capabilities and resources is of paramount importance. Fossil fuel from other continents is not a sustainable energy strategy. Solar energy, wind energy, geothermal energy, hydroelectric energy, tidal energy, sustainable bioenergy, and other renewable resources will define sustainable places in the future.

In physical form, a more sustainable community will always be the more compact, more mixed-use one, particularly if the built environment respects human scale and detail. Sustainable communities must also be connected to, and be a contributing part of, the broader local ecology, including local and regional food supplies. Importantly, sustainable communities are those that perform their basic social function best by better connecting citizens.

A more compact and human-scaled environment creates more opportunities for social capital growth through informal interaction, while mixed-income housing and multimodal integration of residential and work environments build on this potential with different perspectives and experiences. Multigenerational discussion of policy alternatives, with a particular focus on stewardship for forthcoming generations, underlies the sustainability ethic, while open, inclusive, transparent community governance facilitates the holistic, long-term decisions necessary to thrive into the future.

Restoration

A sustainable city is a restorative city. A restorative city invests in its built environment before expanding. A restorative city celebrates its unique history. A restorative city ties human activity to nature; including ample, inviting, and accessible open space; and local and regional food production.

A restorative city respects native flora and fauna. It sequesters carbon. Vigorous urban forestry efforts provide natural habitats, shade, and natural cooling of the urban heat island in order to control costs efficiently and increase property values. A restorative city improves local air and water quality through man-made and natural systems. A restorative city creates greater value, and greater possibilities, for future generations through civic inclusion, social justice, and appropriate public policies and investments.

Local government leaders play key roles in promoting efficiency, respecting diversity, facilitating connective experiences, and being stewards of physical, economic, and social restoration in their communities. They can, should, and must incorporate these themes of efficiency, diversity, connectivity, and restoration into their professional practice if their community is to be sustainable