Sustainable Cities

Sustainable cities are urban centers built on the principles of environmental, social, and economic sustainability, aiming to combat climate change, use resources efficiently, and create inclusive, safe, resilient, and equitable communities. Today, approximately half of the world’s population—3.5 billion people—lives in cities, and this share is expected to reach 60 percent by 2030 and 75 percent by 2050. This rapid urbanization leads cities to account for 60 to 80 percent of global energy consumption and 75 percent of carbon emissions, while simultaneously deepening challenges such as poverty, inequality, and environmental degradation. Within the United Nations Sustainable Development Goals (SDGs) framework, SDG 11 (“Sustainable Cities and Communities”) and SDG 13 (“Climate Action”) stand out as key targets addressing these challenges. Sustainable cities seek to generate positive local and global impacts by transitioning to renewable energy, developing green infrastructure, integrating transportation systems, and enhancing disaster resilience.

Characteristics and Principles of Sustainable Cities

Sustainable cities are defined by the following key characteristics:

• Environmental Sustainability: Use of renewable energy sources (solar, wind, biofuel), reduction of carbon emissions, optimization of waste management, and protection and expansion of green spaces (parks, forests).
• Social Inclusion: Affordable housing for all, access to basic services (water, sanitation, health, education), reduction of social inequalities, and support for vulnerable groups (slum dwellers, informal workers).
• Economic Resilience: Creation of local employment opportunities, promotion of innovative technologies, and investment in infrastructure resilient to disasters.
• Transportation and Infrastructure: Reduction of carbon footprint through bicycle lanes, electric vehicles, public transit systems, and integrated transport planning.

The COVID-19 pandemic exposed inequalities in access to urban services—for example, 1.2 billion people in the Global South live in informal settlements without access to basic services—and highlighted the vulnerability of two billion workers dependent on the informal economy. This situation underscored the critical importance of social justice and resilience in sustainable urban planning.

Leading Sustainable Cities in the World

The following ten cities serve as global models for sustainability, with detailed explanations of their achievements:

Copenhagen, Denmark

Copenhagen is a global leader aiming to become carbon neutral by 2025. Fifty-two percent of its population commutes by bicycle, supported by a network of over 400 kilometers of bike lanes. The “Street Lab” initiative exemplifies innovation through smart parking systems, waste sorting, and air quality sensors. The city has improved energy efficiency using wind power (accounting for 50 percent of energy production) and district heating systems, reducing per capita carbon emissions to 2.2 tCO2 in 2019. Citizen participation and public-private partnerships—such as those with the energy company Ørsted—have been instrumental in this success.

Stockholm, Sweden

Stockholm phased out fossil fuels by 1990 and was named European Green Capital in 2010. Seventy-five percent of its energy comes from renewable sources (hydropower, biofuel). Eighty percent of heating demand is met through energy recovery from waste heat, with a goal to eliminate fossil fuel use entirely by 2030. Ecological neighborhood projects like Hammarby Sjöstad, green roofs, and integrated public transit are hallmarks of the city. Forty percent of its green areas are under protection.

Amsterdam, Netherlands

Amsterdam reduced its carbon emissions by 25 percent between 1990 and 2020. Thirty percent of its electricity is generated from renewable sources, including one of the world’s largest offshore wind farms. Thirty-eight percent of the city is covered by bicycle lanes, with a plan to make all vehicles electric by 2025. Waste management has increased recycling rates to 50 percent, while green roofs and vertical gardens contribute to an environmentally friendly urban fabric.

Zurich, Switzerland

Zurich has reduced per capita carbon emissions to 1.5 tCO2 through renewable energy (80 percent hydropower) and incentives for electric vehicles. Its public transportation system (trains, trams, buses) operates entirely on electricity, with a target of carbon neutrality by 2030. Green building standards such as the Minergie certification, aligned with the “2000-Watt Society” vision, optimize energy consumption. Water conservation projects, including lake and river rehabilitation, further support sustainability.

Oslo, Norway

Fifty percent of Oslo is covered by forested areas, and a carbon tax of approximately 50 euros per ton of CO2 has reduced emissions by 30 percent. The city promotes electric buses and over 100,000 electric vehicles toward a zero-emission transport goal by 2030. With renewable energy accounting for 98 percent of its supply (all hydropower) and green roof initiatives, Oslo offers a lifestyle in harmony with nature.

Vancouver, Canada

Vancouver aims to become carbon neutral by 2050. Ten percent of its population commutes by bicycle, and green spaces such as Stanley Park make up 11 percent of the city’s area. The city is recognized for energy efficiency programs—including LEED-certified buildings—and a recycling rate of 60 percent. Investments in climate-resilient infrastructure, particularly to address sea-level rise, position it as a leader in climate adaptation.

Berlin, Germany

Berlin’s 2015 Smart City Project targets an 85 percent reduction in carbon emissions by 2050. Renewable energy (40 percent from wind and solar) and smart grid systems (for electricity, gas, and heating) have improved energy efficiency. Green spaces cover 20 percent of the city, and bicycle lanes have expanded to 620 kilometers. Recycling rates in waste management have reached 67 percent.

Singapore

Singapore plans to reduce carbon emissions by 36 percent by 2030. Sustainable development within limited space is achieved through smart mobility (MRT metro system) and vertical garden projects like Gardens by the Bay. Waste incineration plants generate energy, and recycling has reached 61 percent. Despite its dense population, per capita green space has increased from 0.8 m² to 1.2 m².

San Francisco, USA

San Francisco launched its zero-waste goal in 2020 with a ban on plastic bags. The city aims to cut carbon emissions by 80 percent by 2050 and is known for its renewable energy (50 percent from solar and wind) and electric buses. Green roof initiatives and public transit—with 33 percent of trips made by bicycle—create an environmentally friendly urban environment.

Tokyo, Japan

Despite a population of 38 million, Tokyo stands out for its zero-waste culture. Public transit—90 percent of which relies on subways and trains—and 200 kilometers of bicycle lanes keep private vehicle use below 30 percent. The 2050 Zero Emission Strategy aims to raise renewable energy to 40 percent and increase waste recycling to 80 percent. Green spaces cover 15 percent of the city.

Sustainable City Initiatives in Türkiye

In Türkiye, metropolitan municipalities have developed projects aligned with SDG 11 and SDG 13 to combat climate change and promote sustainable urbanization:

• Ankara: The Metropolitan Municipality prepared a local greenhouse gas inventory in 2020 through its Local Climate Change Action Plan and developed emission reduction and adaptation strategies. A comprehensive roadmap was created through stakeholder collaboration.
• Konya: Initiated in 2020, the project focuses on climate adaptation through a greenhouse gas inventory and reduction plan. Consultations with internal and external stakeholders and sectoral analyses are included.
• Istanbul: Inventories were prepared for 2010 (40.7 million tCO2) and 2015 (47.3 million tCO2). Sustainability has been advanced through its Climate Change Action Plan Roadmap and risk assessments—for example, infrastructure resilience against floods and heatwaves.
• Gaziantep: The Sustainable Energy and Climate Action Plan, completed in 2018, targets a 40 percent emission reduction by 2030. Adaptation measures have been defined for vulnerable sectors such as agriculture and industry.
• Malatya: A 2020 project to generate energy from waste sludge aims to produce electricity through incineration and generate revenue. Industrial symbiosis and renewable energy models have been developed.
• Muğla: The 2013 Sustainable Energy Action Plan targeted thermal power plant fuel consumption and waste management, aiming to reduce emissions through renewable energy potential.

Sustainability Initiatives at Erciyes University Campus

Erciyes University is taking the following steps toward sustainability at the campus level:

• Transportation: Low-emission shuttle buses powered by natural gas are provided free of charge. Green buses for people with disabilities and the KAYBİS bicycle rental system (first 30 minutes free) are promoted.
• Infrastructure: Bicycle lanes, pedestrian-priority zones, and accessibility for people with disabilities are being expanded. Policies to reduce vehicle access are under development.
• Strategies (2021): Cultural heritage projects (folklore, language preservation), sustainable mobility metrics (vehicle and bicycle counts), campus vision, and green building regulations are being planned.

Challenges and Proposed Solutions for Sustainability

In the Global South, the gap in access to urban services—water, sanitation, electricity—affects 33 percent of the urban population (66 percent in low-income countries). Informal employment (50–90 percent, as in Kenya and India), unplanned urbanization, and climate risks—such as sea-level rise and storms—hinder sustainability.

Proposed solutions:

• Energy: Renewable energy sources (solar, wind) must replace fossil fuels; in Türkiye, energy accounts for 72 percent of emissions.
• Transportation: Integrated systems (public transit, cycling) and electric vehicles must be incentivized.
• Infrastructure: Disaster-resilient construction and expansion of green spaces are essential.
• Governance: Coordination between local (municipalities) and central authorities must be strengthened; Türkiye’s 2050 Climate Strategy supports this step.

Türkiye’s Climate and Sustainability Status

Türkiye’s 2019 greenhouse gas emissions totaled 506.1 million tons, a 130.5 percent increase since 1990. Seventy-two percent stem from energy use, and 13.4 percent from agriculture. Under the Kyoto Protocol (2009) and the Paris Agreement (2021), Türkiye aims to reduce emissions by 21 percent by 2030. The Ministry of Environment, Urbanization and Climate Change leads a 2050 Strategy focused on agriculture and renewable energy. However, local authorities face limited capacity, and both vertical (central-local) and horizontal (inter-municipal) cooperation must be enhanced.

Sustainable cities are indispensable in combating climate change and improving social well-being. Global leaders such as Copenhagen and Stockholm, alongside local initiatives in Türkiye—including Ankara and Istanbul—offer hope. Yet, these goals can only be achieved by addressing inequalities, scaling innovative technologies, and strengthening global cooperation. As of 19 June 2025, sustainable urbanization remains an urgent priority for the planet’s future.