To make cities inclusive, safe, resilient and sustainable.

• Half of humanity - 3.5 billion people - lives in cities today
• By 2030, almost 60 per cent of the world's population will live in urban areas
• 95 per cent of urban expansion in the next decades will take place in developing world
• 828 million people live in slums today and the number keeps rising
• The world's cities occupy just 3 per cent of the Earth's land, but account for 60-80 per cent of energy consumption and 75 per cent of carbon emissions
• Rapid urbanization is exerting pressure on fresh water supplies, sewage, the living environment, and public health
• But the high density of cities can bring efficiency gains and technological innovation while reducing resource and energy consumption

Half of humanity-3.5 billion people-live in cities today, and this number will continue to grow. Because the future will be urban for a majority of people, the solutions to some of the greatest issues facing humans-poverty, climate change, healthcare, education -must be found in city life.

Inequality is a big concern. 828 million people live in slums and this number keeps rising. The levels of urban energy consumption and pollution are also worrying. Cities occupy just 3 per cent of the Earth's land, but account for 60-80 per cent of energy consumption and 75 percent of carbon emissions. Many cities are also more vulnerable to climate change and natural disasters due to their high concentration of people and location so building urban resilience is crucial to avoid human, social and economic losses.

All these issues will eventually affect every citizen. Inequality can lead to unrest and insecurity, pollution deteriorates everyone's health and affects workers' productivity and therefore the economy, and natural disasters have the potential to disrupt everyone's lifestyles.

The cost of poorly planned urbanization can be seen in some of the huge slums, tangled traffic, greenhouse gas emissions and sprawling suburbs all over the world. Slums are a drag on GDP, and lower life expectancy. By choosing to act sustainably we choose to build cities where all citizens live a decent quality of life, and form a part of the city's productive dynamic, creating shared prosperity and social stability without harming the environment.

The cost is minimal in comparison with the benefits. For example, there is a cost to creating a functional public transport network, but the benefits are huge in terms of economic activity, quality of life, the environment, and the overall success of a networked city.

• Take an active interest in the governance and management of your city
• Take notice of what works, and what doesn't in your community
• Advocate for the kind of city you believe you need
• Develop a vision for your building, street, and neighbourhood, and act on that vision. Are there enough jobs? Are you close to healthcare? Can your children walk to school safely? Can you walk with your family at night? How far is the nearest public transport? What's the air quality like? What are your shared public spaces like? The better the conditions you create in your community, the greater the effect on quality of life.

International voluntary work plays a key role in delivering and implementing the Sustainable Development Goals as volunteering supports social, economic and environmental change. It is an important driver of civic engagement in the 21st century. If you want to do more than just join the conversation, Volunteer World provides the chance to become active and help reach the SDG Goal #11 Sustainable Cities And Communities. Click on the map to search for volunteer opportunities that help to achieve the Sustainable Development Goal: