In 2018, the United Nations Department of Economic and Social Affairs (UNDESA) published a report titled 2018 Revision of World Urbanization Prospects. The report suggests that while in 2018, 55 per cent of the worlds population lived in urban areas, this proportion is expected to increase to 68 per cent by 2050. Around 90 per cent of this increase in urban population is estimated to take place in Asia and Africa. Together, India, China and Nigeria will account for 35 per cent of the projected growth of the worlds urban population between 2018 and 2050, the report states, adding that India alone might account for 416 million added urban dwellers.What a rise in urban population means for sustainabilityThe revelations of this report have since spurred experts from all fields, from economists to public health officials, to ponder upon the logistics and scenario involved if this projected growth rate does come true. Many studies suggest that the outlook for urban dwellers, especially in countries like India, is anything but promising. For example, a 2019 study published in the journal Frontiers in Sustainable Cities (titled Grand Challenges in Sustainable Cities and Health) suggests that although, historically, urban populations have been more affluent and healthy compared to rural dwellers, the tide is turning against them due to climate change and unhealthy lifestyle choices.The pattern being observed is that non-communicable diseases (NCDs)also known as lifestyle diseases like heart disease, obesity, hypertension, mental illness, etc.are increasing among city dwellers and affecting their quality of life. Further, cities are not homogenous and all-inclusive. In countries like India, those living in urban slums, migrants and socio-economically deprived populations tend to be disproportionately affected by pollution, climate extremes, and lack of clean water and sanitation. Add to this the hard fact we all had to face over the course of 2020 and 2021: Infectious diseases like COVID-19 spread much faster in urban centres, and their effect can be disastrous. The World Bank suggests that the threat of natural disasters due to climate change also complicates these challenges to urbanisation.It is for these reasons that the UN and its members, as well as the 196 countries that signed up for the historic Paris Agreement on climate change in 2015, all agree that building more sustainable cities and communities is a vital part of their agenda for the future. In fact, it ranks 11th on the UNs list of Sustainable Development Goals.Building a sustainable city, and the role you must playNow, you may easily ask if you even have a role to play in building a sustainable or eco city. After all, doesnt the making of a city rely on governments, policymakers and those professionally equipped to build one from the ground up? The simple answer is yes, it does. A 2019 study titled Generating a vision for smart sustainable cities of the futurepublished in the European Journal of Futures Research explains that there are many actors involved in the making of sustainable cities. This not only includes engineers, architects, green technologists, environmentalists, social scientists, urban planners, local and national government agencies, but also computer scientists, data scientists and digital tech wizards of all sorts. After all, we have now moved towards building sustainable cities which are also smart.But heres something you should know: all these actors are quite likely to be city dwellers just like you. As a citizen, your role isnt diminished or non-existent because someone elses is more highlighted and visible. In fact, as a study published in the journal Environmental Science Policy in 2020 (titled Pathways to urban sustainability through individual behaviours), since individual decisions and actions directly contribute to contemporary environmental problems, environmentally responsible behaviour at the individual level is crucial to solving the same. Urban sustainability would be impossible without pro-environment behaviours by every single city dweller. The study even suggests that if you have sufficient social capital (meaning, a network of people based on trust and reciprocity), then you could even initiate change at the community level within your city.So, what actions can you take all by yourself to build a sustainable city? Here are a few ideas you must try.Reduce your wasteWhether its plastic bottles and packaging, old clothes, aluminium foils or food, urban landfills are overburdened by the immense amount of waste city dwellers produce every single day. Reducing this amount of waste by buying or using what you absolutely need instead of extravagant desires can help a lot. So can making wiser choices while shopping (like buying reusable, organic or biodegradable products), reusing, recycling and even upcycling the things you use. If its food waste that worries you, then contact food banks and charities in your city about managing them better.Mind the lightUrban dwellers do tend to use more electricity than those living in rural areas. In fact, you could take a closer look at your electricity consumption and monitor any waste in this field. A simple action like switching off the lights, fans and plug points when you leave the room, or buying eco-friendly or energy-efficient bulbs and electronics, can go a long way in reducing your carbon emissions.Go public While using public transport like local trains, buses, metro and car pools may not be a good option during the pandemic, using them when the situation improves can help reduce your use of fossil fuels and daily carbon emissions. If you are in the market for a new car or personal vehicle then go for an eco-friendly one which has less emissions and uses sustainable fuel options. Another option, which is also a healthy one, is getting a good bicycle and using your own energy to drive yourself places.Bring nature home No matter where you live, you could buy a few pots and plant a few seeds to get closer to nature. You may not have a garden, but you can still grow fruits, veggies, flowers and microgreens on your balconies and window sills. If you live in an apartment society with a residents welfare association, you could propose a community garden in terraces or common areas which could benefit everyone. There are also many initiatives across cities to reclaim land for urban agriculture and urban forests which you could contribute to or volunteer for.Focus on your healthEat a healthy, balanced diet, get enough exercise, and take your health parameters very seriously no matter what your age. Doing this can reduce your risk of NCDs and reduce the burden on the public healthcare system. Similarly, continuing to take precautions like social distancing and wearing masks can reduce your risk of communicable diseases like COVID-19. If the citys resources are freed up, better focus on areas that are lagging behind can be provided, ensuring disparities are dealt with immediately and the city becomes truly sustainable.Reconnect with the ruralBelieve it or not, urban areas are largely dependent on surrounding rural areas for essentials including food, water and labour force. You could break the rural-urban divide and make the entire system more sustainable for the future with simple steps like buying local produce, and going for local labour and artisanal products. This ensures their job safety, generates more employment and helps create a self-reliant ecosystem within every rural-urban periphery.