Cities generate two-thirds of global energy demand and greenhouse-gas emissions, prompting much discussion on the neededrole of local authorities in combating climate change. Global networks of city leaders have reaffirmed their commitment to doing their share to achieve global climate targets, and the number of such mayors is ever increasing. As exciting as it is to see such momentum from cities, we should take this with some skepticism.

In countries where governance is top-downand land use is within state or national jurisdiction, mayors often are merely glorified urban managers in charge of ensuring proper public service delivery. Therefore, handbooks and other guidance offering “solutions” for cities to combat climate change through mayoral action typically limit themselves to efficiency gains in service delivery and energy use.

Even then, this approach is of limited facility. After all, in countries where code enforcement is weak to non-existent — such as in India and China, where wealth is fast-growing and people are demanding access to luxuries such as air conditioning — stricter energy-related building codes are substantially undermined by corruption and bribery. If you cannot change efficiency, the only realistic strategy left is to reduce carbon-based generation, which for the most part falls beyond the purview of a city’s capability.

Local action by cities in developing countries is just as important as federal or state action, whether it be megacities or the “tier two” areas that are poised to be the New Yorks and Shanghais of tomorrow. Tier-two cities, in fact, are in a better position to deliver on global carbon goals than existing megacities, as new developments are easier to guide in the desired direction when compared with reshaping an existing urban fabric.

But for cities to realize this potential, we need to switch focus to more-realistic interventions — the kind that many urban planners have long professed. Indeed, current conversations about climate change are not paying adequate attention to several key city issues, such as urban design, land-use planning and zoning interventions.

These are perhaps the most important tools that cities can harness to shape a carbon-neutral future. But today they are being vastly underutilized, particularly amid the greater focus on city-led climate action.

Powerful tools

The largest portion of greenhouse-gas emissions from cities today comes from energy use inresidential and commercial buildings, and transportation. For better and worse, the invention of the modern HVAC system allowed for construction to pay less consideration to the design implications of the immediate environment and microclimate.

Thus, cities have allowed the construction of tall, glass skyscrapers and concrete-box buildings with reduced setback regulations, because of their modern appeal and space efficiency. As a result, more and more urban units lack natural ventilation and lighting; today, roughly 70 percent of building energy use goes into lighting and HVAC.

Proposed solutions in the transportation sector are limited to replacement of old buses with new electric or hybrid vehicles, and increasing the frequency of public transport. But without the proper density to support ridership, and economic disincentives to induce behavioral change such as congestion pricing, the expected benefits would be marginal at best.

Can cities not create urban policies that require developers to better design high-density developments, such that energy use is minimized through the maximized use of natural resources? Stuttgart, Germany, seems to be doing well on this.

Sprawled growth, which often is associated with very large carbon footprints, can be contained and even reversed, as in the U. S. city of Phoenix, through smart re-zoning and provisions for mass rapid transit to create more transit-oriented development.

Site design and architectural changes are essential but also just one input to urban climate action. In order to maximize carbon reduction, an integrated, citywide approach would need to be implemented. For example, the planting of trees should be synergized with a city’s drainage systems in order to minimize energy use for plant watering. Waste-dumping grounds can be re-zoned and re-purposed as recreational spaces. Both of these do double duty as excellent carbon sinks.

The planning and design community has been pushing for the adoption of such an approach by establishing certification standards such asLEED neighbourhood development standards(or similar), which promote walkability, bikeability and generally a more human-centric design approach. But cases where such standards have been implemented remain hard to come by, beyond the building level.

One might argue that a city government generally caters to the desires of its residents and that people vote with their feet. But there are zero-carbon development models for both groups: those that prefer suburban lifestyles, such as the BedZED community in London, as well as medium density, mixed-use urban lifestyles like the Hammarby model.

Creating multiple central business districts can help with reducing trip distances and managing population densities in different parts of the city.

Long-term thinking

Still, amid all of these strong examples, an uncomfortable fact remains: States and national governments are currently better positioned than cities to act on broader issues around carbon emissions. So while cities may be the site of two-thirds of carbon emissions, city governments often do not have the authority to make substantive changes in line with their apparent potential through mayoral action.

That’s not to undermine the actions that cities can spur. City officials can mandate that residents move to energy-efficient light bulbs, or require businesses to keep their doors closed if the air conditioning is on. They also can ban the use of plastics or issue carbon challenges. Certainly, every bit counts.

Nonetheless, if cities are to play a major role in climate change, it is essential to make use of the strongest tools at their disposal: urban planning. Mayors who have pledged themselves to climate action need to look beyond short-term solutions and pursue long-term sustainability through opportunities that urban planning offers in shaping our cities. Then, they need to catalyse that pursuit with their political prowess.

In particular, stricter controls need to be established on new market-driven construction to reduce future energy dependence, and efforts must be ramped up to redesign and reshape our existing urban fabric. Failure to act swiftly on both will otherwise result in same results we have seen before.