Cities cover just 2% of the earth’s land surface. But within their perimeters, they consume 75% of the planet’s material resources. To calculate the amount of materials consumed by cities in the production of space, the UN uses the Domestic Material Consumption (DMC) as a measure. The DMC takes into account all raw materials extracted from the domestic territory per year, plus all physical imports, minus all physical exports. In terms of material footprint, the world’s richest nations consume ten times as much as the poorest, and twice the global average. Consumption is uneven across the different world regions. Based on the total urban DMC, Eastern Asia leads the world in material consumption, with China consuming more than 50% of the world’s concrete and aluminium.
The Population Division of the Department of Economic and Social Affairs (DESA) of the United Nations estimates that by 2050, two out of every three people are likely to be living in cities or other urban centres. This means that around 2.5 billion people could be added to urban areas by the middle of the century. To support this shift, every year, from cradle to gate, we produce an immense amount of materials to supply the continuous construction of the human-built environment. This emerging pattern highlights the need for more sustainable urban planning. We are in the midst of the convergence of global urbanization, an unstoppable climate rebellion driven by the idea that another world is possible, and digital transformation.
By 2028, New Delhi will become the most populous city on earth. Currently, Tokyo is the world’s largest, with an agglomeration of 37 million dwellers, followed by New Delhi (29 million), and Shanghai (26 million). Mexico City and São Paulo, come next; each with around 22 million citizens. By 2030, the world could have 43 megacities, with most of them in developing economies. This is an increase from 31 today. These swelling urban populations will place extra demands on both resources and services in urban areas. Consumption in Asia is expected to spiral as the continent hosts the majority of the world’s new megacities—cities that will house over ten million people. The biggest jump in the next decades, however, will happen in Africa. Africa is expected to double in population by 2050, with material consumption jumping from 2 billion tonnes to 17.7 billion tonnes per year.
In 2018, the world urban population reached 4.2 billion. In 1950, it was a mere 751 million. For the first time in history, over 4.3 billion people, or 55% of the world’s population now reside in urban settings. It is expected that this figure will increase to 80% by 2050. The World Economic Forum estimates that 64.1% of these citizens will be residing in developing countries, while 85.9 % of the population in the developed world will be living in urban areas. With the expansion of cities, material consumption is expected to grow from 4.1 billion tons in 2010 to 88.8 billion tonnes by 2050. The Population Division of the UN Department of Economic and Social Affairs (UN DESA) shows that the most urbanized regions include Northern America (with 82% of its population dwelling in urban settlements in 2018), Latin America and the Caribbean (81%), Europe (74%), and Oceania (68%). The level of urbanization in Asia is presently nearing 50%.
Low-carbon and resource-efficient cities are a priority if the world intends to mitigate the consequences of increased material consumption, especially since most of the anticipated increases are highly concentrated in just a handful of countries. The largest growth is expected in the cities of the Global South, particularly in China, India, and Nigeria. Collectively, India, China and Nigeria will account for 35% of the projected growth of the world’s urban population during the period 2018 to 2050. By 2050, it is anticipated that India would have added 416 million urban inhabitants, China 255 million, and Nigeria 189 million.
In the IDB publication, “The Road Toward Smart Cities: Migrating from Traditional City Management to the Smart City, (2016) the authors state that large metropolitan centres and megacities are complex systems with layered and multiple connections across their different ecosystems and individuals. This demands urban planning that permits fluid decision-making mechanisms, that includes citizen participation processes. In the IDB report cited above it states that, “Managing and improving cities requires knowing what happens within them, in their different regions. This is only possible with changes in government structures and in the communication and participation processes of the different actors responsible for managing them”, (p.13).
Cities in countries experiencing these complex changes in population demographics will face many challenges in meeting the needs of their blossoming urban populations. Presently, global urban DMC is at a rate of 8–17 tonnes per capita per year. With the world population expected to increase by almost two and a half billion people by 2050, existing and new cities must accommodate many of them within a built environment that does not aggravate existing troubles concerning air quality, wastewater management, and carbon emissions. These changes, therefore, offer an opportunity to develop low-carbon and resource-efficient cities of the future.