World's Megacities With Major Problems And Smart City Solutions

The United Nations Office in Geneva published a report on November 18, 2025 titled 'Cities now home to nearly half of humanity.' The number of megacities, the urban regions with more than 10 million residents has risen to 33, compared to only eight in 1975.

A news report in Al Jazeera on November 26, 2025 with the heading "Indonesia's Jakarta now the World's largest city, Tokyo falls to the third: UN." The article said a United Nations report found that Indonesia's capital Jakarta is the world's largest city with about 42 million people, followed by Dhaka in Bangladesh home to almost 40 million, and Tokyo around 31 million.

A low-lying coastal city located in the west of of the densely populated island of Java, Jakarta rose from second place to replace Tokyo. The Japanese capital with a steady population of 33.4 fell to third place behind the densely populated Dhaka which jumped to second place of 36.6 million and projected to be the world's largest by 2050.

Still Growing Alongside their Problems

Only 40 per cent of its citizens have access to clean, pipeline water, leading many to to tap the groundwater. This pumping, alongside rapid urban development has resulted to its sinking.

This isn't Jakarta's only infrastructure problem; the city's traffic and air pollution is considered one of the worst in the world, alongside its rapid, sprawling urban expansion resulting in drastic loss of green spaces.

Dhaka's rapid growth has partly been driven by people from rural areas moving to the capital, searching for opportunities or fleeing from hometowns due to problems including flooding and rising sea levels, made worse by climate change.

Dhaka experiences poor air quality due to vehicle emissions and stagnant conditions, which can cause respiratory issues, and poor health conditions.

Tokyo faces problems including housing shortage, high costs, and long commutes, largely driven by high population density and concentration of economic activity. Other issues are overcrowding and chaotic public transport system and lack of sufficient green spaces. Other issues are threat of natural disasters and long term effects of climate change.

Emerging Urbanization in the World Population

Today, cities produce around 80% of the global GDP and this importance is likely to continue. Cities also use 75% of global energy and are responsible Accompanying the pace and extent of urbanization are a number of positive and negative trends - from increased economic opportunities and improvements in lives and livelihoods, through to the potential for greater urban-rural disparity, lower quality of life, and conflict. One thing is clear, cities across the world play a critical role in driving their development.

However, cities today face numerous vulnerabilities and threats. Without proper planning, policies, and support, urbanization often leads to unnecessary risks and costs, preventing cities from reaching their full potential. Cases such as urban sprawls and the proliferation of informal settlements are increasing, and the communities who reside in such areas often suffer from the poor provision of public services (or lack of) such as healthcare or waste management systems.

As their population grows, cities also become more complex, making long-term planning and city management a challenge. Amongst the numerous challenges that policymakers must tackle include those that are environmental, those pertaining to resource allocation, and even social challenges such as reducing intra-city inequalities.

Cities are providing a wide range of opportunities and possibilities for its citizens - and in order for them to be fully harnessed - cities should be built for and together with its citizens to fully unlock their potential. This includes taking into account the various needs and aspirations of people, making sure that everyone can have equal and inclusive access to services and create urban spaces and environments to enhance livability.

A new UN report says by 2050, two of every three people are likely to be living in cities or other urban centers highlighting the need for more sustainable urban planning and public services,

Most of the increase is expected to be highly-concentrated in just a handful of countries. "Together, India, China and Nigeria will account for 35% of the projected growth of the world's urban population between 2018 and 2050... It is projected that India will have added 416 million urban dwellers, China 255 million and Nigeria 189 million," said UN Department of Economic and Social Affairs.

Emergence of Megacities With More Than 10 Million Inhabitants

These swelling populations will place extra demands on both resources and services in urban areas. At the same time, linkages between urban and rural areas will need to be strengthened, building on their existing economic, social and environmental ties.

"Many countries will face challenges in meeting the needs of their growing urban populations, including for housing, transportation, energy systems and other infrastructure; as well as for employment and basic services such as education and health care," said the report of UN Department of Economic and Social Affairs, urging governments adopt better integrated policies to improve the lives of both urban and rural dwellers

Challenges for the Cities of the Future

The Biggest Problems facing cities

As more people move to cities, they strain resources and exacerbate existing problems like traffic congestion, poverty, inequality, and lack of affordable housing, creating a cycle of increasing complexity and demand for services. This is further explained in the following:

Environmental problems

1. Pollution. Air pollution from car and industry, water contamination from urban runoff ad waste, and overall poor air quality present significant health risks.
2. Climate change. Cities are disproportionately affected by climate change, with many facing threats like sea-level rise, extreme heat, and flooding.
3. Resource strain. High population density puts a strain on resources, leading to high energy consumption and issues with waste disposal and water availability.
4. Habitat loss. Urban development can lead to the loss of green spaces and disrupt natural ecosystems.

Social and Economic Problems

1. Housing. Affordable housing is a major crisis, with high prices and shortages pushing many people out of the cities where they work.
2. Maintenance of Infrastructure. Rapid growth often outpaces the ability to build and maintain infrastructure, leading to problems such as traffic congestion and overloading public transportation system.
3. Inequality in Incomes, and its associated poverty. Cities often have high levels of income inequality and poverty, which can lead to societal crimes and social breakdown.
4. Strain on public service. A large and growing population puts strains public services such as sanitation, education, public safety and fire protection, especially when budgets are inadequate to meet the increasing needs.

Interconnection of the above Problems

Urbanization in Unbelievable Figures

Such fast-paced urbanization is increasing the number of megacities with more than 10 million inhabitants. The UN predicts there will be 43 of these metropolises by 2050.

Rural flight is also accelerating the growth of cities with populations between 100,000 and 500,000, which today are home to more than half of the world's urban population. In addition, it is often difficult to distinguish between a city, its suburbs, and the increasingly interdependent communities of surrounding villages. In short, there is no escaping urbanization.

The Need for Sustainable Development

1. Managing traffic flows to ensure that people get to and from work and leisure activities, that food and goods can be supplied as needed, and other cities can be easily reached in an increasingly interconnected world.
2. Reducing the industrial and automotive pollution for good air quality, preserving water resources
3. Reducing waste products generated by use of resources.
4. Carefully controlling energy use to curb environmentally harmful greenhouse gas emissions. This may involve constructing low-energy buildings or even positive-energy buildings, which produce more energy than they consume.

Active participation in eco-districts, and participatory democracy

Cities have increased civic participation. This has fueled a movement toward "participatory democracy", where residents are not only consulted on projects but also encouraged to make their own tangible proposals to the local government.

Five ways to make cities more sustainable and resilient

Dr. Simone Sandholz of the United Nations University on October 13, 2018 suggested the following 5 ways to make cities more sustainable and resilient.

1. Urban transport systems need to become more sustainable

2. Nature-based solutions for cities

3. Community networks in support urban disaster resilience

4. Smart solutions can improve urban livelihoods

For example, in Kenya smart metering by means of mobile money enables enables payment for utilities and transportation and provide equal access. Furthermore, the mobile money provides help between urban and rural areas, and particularly helpful for female households.

5. Cities, countries, and international bodies need collaboration

For example, the United Nations held a conference on Housing and Sustainable Urban Development called Habitat III when 167 countries participated to focus on sustainable urban development and adopted a "New Urban Agenda." While cities around the world are implementing good ideas, it is this kind of global collaboration that needs implementation. There is overcrowding and chaotic public transport system and lack of sufficient green spaces. Other issues are threat of natural disasters and long term effects of climate change.

Smart city program of the UNDP Global Center

For the Global Centre, smart cities are about using innovation at its broadest - whether technology, different ways of working, or even nature-based solutions - to improve the urban environment. Technology has significant potential to make a difference, but improvements can also come from good city management, skilled public workers and well-planned public realms, and citizen engagement and inclusion. Smart cities are about people, and not just about technology.

The underlying technology and innovation that underpins any smart city initiative, although sometimes complex, is often the simplest aspect. The failures of small cities are often due to organizational culture, difficulties in achieving behavioral change, lack of technical expertise and leadership, and a singular focus on technology, as opposed to the needs and realities of users and intended outcomes. Experienced smart city experts can minimize or reduce these risks.

The UNDP Global Center works with offices of the country concerned to ensure the success and sustainability of smart city project.

Six ways Singapore leads as the world's Smartest city

1. Mobility as a shared community experience

With land at a premium, Singapore uses sensor technology and an autonomous fleet for the elderly and disabled mobility. The city also features an electronic road pricing system to manage traffic congestion. And students at the National University are ferried around campus on a self-driving shuttle.

To help with transport optimization, public data is used in a trial to facilitate transport planning. Data from fare cards to sensors in more than 5,000 vehicles and the real-time tracking of busses, is analyzed to reduce the rate of over-crowded buses by 92%. Contactless technology is used to streamline the movements and payments of the 7.5 million passengers who use public transport each day.

Meanwhile, the travel smart program to more evenly distribute morning peak hour demand on the rail network is used to encourage citizens to re-think when they travel, how they travel. and reduce the amount they travel to encourage remotely.

2. Healthier citizens

With 47% of Singapore's population projected to be over 65 by 2050, the city has digitized healthcare to manage this aging demographic. Singapore's e-health initiative is a comprehensive digital platform that aims to improve the quality and accessibility of healthcare services in the country.

The initiative is driven by the Ministry of Health, and the Infocomm Media Development Authority, and it involves various stakeholders in the healthcare industry, including healthcare providers, technology companies, and patients. Some of the e-health platform are following 4 key components :

• Health Hub, an online health portal that allows patients to manage their health and wellness providing features such as appoint bookings, prescription refills and access to medical records.
• Telemedicine enables patients to consult with doctors remotely through video conferencing or messaging, which is especially useful for patients who live far from healthcare facilities, or have mobility issues.
• Tele Rehab allows patients to undergo exercises in their own home. Wearable internet devices monitor patients' progress and transmit the data to their therapist over a wireless network.
• Robotics help to reduce loneliness in an aging population through artificial intelligence chat bots talk to the elderly, telling them about community activities, and itegrate messages that promote healthy living. The AI-powered smart elderly alert system monitors and learns people's regular movements, and alerts a caregiver when something out of the ordinary occurs, and urgent care might be required.

With 99.9 percent of the population owning a smartphones by 2026, the Smart Nation app can easily offer Singaporeans a one-stop platform for accessing government services services and information, simplifying interactions actions with the government. Some of the app features might include the following areas:

• Digital Identity. This app allows users to create a digital identity, which can be used to access a range of government services, such as applying for permits and licenses.
• Government Services. This app provides access to a wide range of government services, including payment of fines, renewal of passports, and booking of government facilities.
• Feedback and Reporting. This app allows citizens to provide feedback and report issues such as broken public facilities or incidents of littering.
• Personalized Information. This app provides personalized information based on user's location and interests, suc as news and events happening in user's vicinity.
• Emergency Information. This app provides real-time updates on emergencies and incidents happening in the user's area, such as traffic accidents or natural disasters.

4. Supporting Business

Singapore's digital district merges the Singapore Institute of Technology with a business park, which aims to foster development in cybersecurity and its internet technologies by enabling better integration between industry and academia. A data-sharing collaborative has also been established, to encourage transparent business interactions. And businesses that transact directly with the government can now do through an online hub that enhances what the city calls "cyber hygiene".

5. Learning to be smart

Singapore is educating using artificial intelligence, under its Tech Skills Accelerator program intiatives - AI for Everyone and AI for Industry - led by AI Singapore, which will support the upskilling of 12,000 professionals and students in AI.

6. Singapore's Virtual Twin

One of the most groundbreaking innovations is the creation of Virtual Singapore, the world's first national-scale digital twin integrating this high-resolution, data-rich 3D model of the city in real-time data on buildings, infrastructure, population movements, and environmental factors to provide a powerful tool for urban planning and management.

Virtual Singapore enables simulations for sustainable development, emergency response, and infrastructure optimization, allowing government agencies, urban planners, and researchers to test various scenarios and make data-driven decisions.

The platform also fosters collaboration across public and private sectors, improving infrastructure management, disaster preparedness, and urban growth strategies. With continuous updates, Virtual Singapore is set to remain a dynamic resource for managing the city's evolution, ensuring that Singapore stays at the forefront of smart city innovation.

The city also has a digital national identity system, a Smart National Sensor Platform to encourage citizens to be part of the change towards the city becoming "digitally ready", and proactively spearhead this movement.