Cities have leapt ahead of slow-moving bureaucratic national governments to create more sustainable living environments.
This year, C40 and Siemens have picked 10 cities that are leaders in urban transportation, carbon measurement and planning, energy efficient buildings, air quality, green energy, adaptation, sustainable communities and waste management.
Projects for consideration were culled from both C40 members and the 120 cities profiled in its Green City Index. An independent seven-member panel of former mayors, architects and representatives from the World Bank, C40 and Siemens picked the winning city projects in 10 categories.
Here are the top 10:
Bogota, Colombia- Urban Transportation
The city's rapid transit system Transmilenio was launched in 2000 to transport more than 70 percent of its population and, as a result, has reduced annual emissions by 350,000 metric tons. Now the city (pictured above) is working to replace the current diesel fleet with hybrid and full electric buses with an aim to reach 100 percent conversion by 2024. Bogota also started an electric taxi pilot program and has pledged to convert 50 percent of its cab within the next 10 years.
Copenhagen - Carbon Measurement & Planning
Copenhagen's 2025 Climate Plan put it on track to become the first carbon neutral capital city. The plan includes a goal to lower energy consumption in commercial buildings by 20 percent, households by 10 percent and public buildings by 40 percent. Street-lighting will use 50 percent less energy and all of the city's electricity consumption will come from renewable sources by 2025.
Melbourne - Energy Efficient Built Environment
Melbourne has created a sustainable buildings program that encourages building owners and managers to improve energy and water efficiency and reduce their waste to landfill. The city government has set a target to reduce carbon emissions from the commercial sector by 25 percent and from the residential sector by 20 percent. The city will achieve that through environmental standards on new buildings as well as financial incentives and advice for upgrading and retrofitting existing buildings, according to C40 and Siemens.
The so-called 1200 Buildings program was designed to encourage the retrofitting of 1,200 commercial buildings, about 70 percent of the city's commercial buildings stock.
Mexico City - Air Quality
Mexico City has struggled for decades with air quality. In 1992, the United Nations named Mexico City the most polluted city on the planet.
A series of plans called ProAire have helped the city curb its once ubiquitous smog and reduce its carbon emissions by 7.7 million metric tons between 2008 and 2012. To achieve that target, the city took aggressive measures including closing its most polluting factories and banning cars one day per week in its metro area.
Munich - Green Energy
In 2009, the city set a goal of achieving 100 percent renewable energy supply--at least 7.5 billion kilowatt hours per year--by 2025.
The city-owned utility company Stadtwerke München (SWM) has focused on cost-efficient projects that are self-sustaining. Water, geothermal, solar biomass and wind power all play a role in SWM's strategy.
New York City - Adaptation and Resilience
Hurricane Sandy brought a 14-foot storm surge upon New York City, flooding subway stations, roads, and electrical facilities and bringing transportation networks to a standstill.
Six months later, the city released its "A Stronger More Resilient New York" plan that includes more than 250 initiatives to protect the coastline and strengthen its buildings and the vital systems that support the city such as the energy grid, parks, transportation systems, telecommunications networks, healthcare system and food and water supplies. The plan is in its first phase, which is focused on resilience of buildings and power infrastructure.
Rio de Janeiro - Sustainable Communities
A 2010 census revealed an estimated 22 percent of Rio de Janeiro's population lives in informal settlements or slums, called favelas. And most of these lack adequate sanitation or building standards. The city's Morar Carioca Program aims to provide integrated development and services to incorporate these areas into the more formal communities they typically border. The government aims to formalize all of its favelas by 2020 to improve living conditions for up to 232,000 households.
San Francisco - Zero Waste Program
The city's zero waste efforts have pushed landfill diversions from 35 percent in 1990 to 80 percent in 2010. Last year, the city disposed of 428,048 metric tons of material, the lowest level on record. Mandatory recycling and composting increased organics collection 50 percent to more than 600 metric tons per day, more than any composting program in the U.S.
Singapore - Intelligent City Infrastructure
Singapore has a lack of space and a booming urban population, a combination that has made traffic management a challenge. the city-state has implemented an Intelligent Transport System along with a number of initiatives including free public transportation in pre-morning peak hours, a vehicle quota system, congestion charge and extensive public transport system. Singapore also has an electronic road pricing system, which are tolls that vary according to traffic flows.
Tokyo - Finance and Economic Development
Tokyo launched the world's first urban cap-and-trade program April 1, 2010, requiring carbon emissions reductions from large commercial, government and industrial buildings through on-site energy efficiency measures or participation in the emissions trading scheme. Under the program, Tokyo set the cap at 6 percent for the first compliance period of fiscal year 2010 to FY 2014.
In its first year, the participating 1,159 facilities reduced emissions by 13 percent in total. Reports submitted at the end of November 2012 bring the second-year total to an overall 23 percent emissions reduction below the base-year (2000) emissions.
Photos: C40 Cities Climate Leadership Group/Siemens