01/27/2014 05:43 pm ET Updated Jan 27, 2014

Five Cities Restoring Their Ecosystem Equilibrium

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Sustainable cities are on the rise and with good reason. Due to the rapid growth in population, there is an increase in demand for all resources, especially energy, technology and space.

Although maintaining a balance with the ecosystem may be difficult, these cities both large and small around the world are showing us how sustainability could be done.

is the capital of Iceland and also the smallest green city on our list with a population of 115,000 people. By year 2050, the country has plans to freee itself from fossil fuel dependency and become an economy living on hydrogen energy. Reykjavik currently harnesses energy and produces electricity purely from geothermal sources and hydro-power. The city not only has the largest geothermal heating system in the world, but many of the vegetables they consume are grown in greenhouses heated using the geothermal system and use hydroelectricity for lighting. It is also popular for its hydrogen-fueled buses. Iceland has adopted an overall environmental policy that minimizes the country's carbon footprint while using their natural resources optimally.

Portland, Oregon is literally one of the greenest cities in the U.S. with over 90,000 acres of public green spaces from parks to trails. With over 700 miles of bicycle paths around the city, a quarter of the city's population commutes using alternative transportation like biking, public transportation, or carpooling. The city currently has 50 buildings that are certified by U.S. Green Building Council, 50 percent of the city's power comes from renewable sources and 63 percent of the city's waste is recycled.

Chicago is quickly becoming a candidate as a major green metropolis in the Midwest. With over 300 bike trails, 13 green hotels, and 7 million square feet of green roofs, the windy city is defining how to take sustainability to new urban heights. Their well-rounded approach includes initiatives such as establishing the Chicago Standard for construction which supports environmental initiatives in the construction process to save energy, resources, and operating costs.

Vancouver is known for its beautiful landscape, but its plans to become the world’s greenest city by 2020 are also quite impressive. The metro oasis has over 18 miles of waterfront and 200 parks. With over 90 percent of its power generated from renewable sources, the city is on track to start incorporating more sources such as tidal and wave energy. Moreover, Vancouver is the largest promoter and user of hydroelectric power and has even developed a sustainability plan for the next 100 years. The Vancouver Convention Center holds a mini sanctuary for wildlife and plants made with a 2.4-hectare rooftop garden. The garden consists of a massive variety of insects, bees and birds, and 400,000 indigenous plants and grasses are added to the ecosystem.

San Francisco shines as a starring example of a sustainable city with over 70 projects with LEED certification. San Franciscans are the pioneers of banning the use of non-recyclable plastic bags in large grocery stores, keeping 100 million plastic bags from ending up in the trash per year. The city has more than 17 percent of public space devoted to parks and green sanctuaries, and 50 percent of people commute via alternative transportation. It also keeps almost 90 percent of discarded materials out of landfills through recycling. It continues to invest in renewable energy such as solar, wind, hydro, geothermal, biomass and biofuels as it moves towards its citywide goal of being 100 percent reliant on renewable electricity supplies.