It was November 15, 2022 when the global population crossed the <a href="https://www.thenationalnews.com/world/2022/11/16/global-population-passes-8-billion-in-pictures/" target="_blank">8 billion mark</a>, fuelling the debate about our impact on the planet. However, according to UN projections, this year will be equally historic as <a href="https://www.thenationalnews.com/world/asia/2023/04/19/india-to-surpass-china-to-become-worlds-most-populous-nation-within-months/" target="_blank">India is about to pass China</a> as the world’s most populated country. Although the exact moment of this shift cannot be pinpointed — India has not conducted a national census since 2011 — it is undoubtedly a pivotal moment in the history of mankind and one that carries its own significance, symbolism and resonance. Critically, it also has serious implications for <a href="https://www.thenationalnews.com/world/2021/10/05/extreme-heat-caused-by-urbanisation-global-warming-threatening-cities-says-study/" target="_blank">urbanisation and the future of cities across the world.</a> India is passing China at time when both countries’ populations are about 1.4 billion people. However, their dynamics and momentums differ significantly. China has been leading the population chart since the 1950s, when the UN started monitoring data on a global scale. The country hit the one billion mark in 1980, compared to 1997 for India. China’s one-child policy, introduced in 1980 as a means to control growth and resources, heavily affected population growth and fertility rates. Even though that policy was updated in 2016 with the introduction of a two-child rule, growth and fertility did not bounce back. Provided that these rates remain the same, China is expected to reach its maximum population by 2031 and then start declining. India’s population is currently growing four times faster than China’s, at rates of 0.93 per cent and 0.25 per cent respectively. India is also expected to reach its maximum population of 1.7 billion people by 2064, according to an average scenario projected by the UN. A lack of restrictive policies are thought to be the main drivers behind the country’s growing population. Remarkably enough, the most significant parameter contributing to India’s galloping growth is its population’s age composition. India’s average age is only 28 years old whereas China’s is 39. About two thirds — 65 per cent — of India’s population is below 35 years of age while more than a third of Chinese citizens will be 65 years old and above by 2050. Even more significantly, roughly 20 per cent of people globally who are under the age of 25 live in India. Such healthy <a href="https://www.thenationalnews.com/opinion/comment/demographic-change-is-an-age-old-problem-1.846410" target="_blank">demographics </a>may lead to a more robust and thriving economy. A young population feeds the overall available workforce and also generates mobility in terms of education, technological literacy and entrepreneurship. Interestingly, women are only a fifth of the labour force in India but almost 45 per cent in China. Furthermore, an increasing and better-educated workforce may be able to put constraints on the migration balance, which is currently negative for India. Such a workforce can generate demand for growth and eventually contribute more to an increased GDP. Indicatively, India’s GDP is expected to grow from 2016 to 2050 by 8 per cent, whereas China’s will grow by 2 per cent. However, India will not be able to surpass China in terms of the GDP, as there are many more contributing factors keeping China ahead. It must be stated though that these numbers and the two countries’ position in this population race extend far beyond than a mere encyclopaedical reference or a high-school comparison. It reminds us of the special role of cities within a global context throughout our history and of our special position on the planet. This is a position filled with the privilege of having acquired the knowledge and understanding of nature as a system. This position also brings with it an obligation to provide answers, to preserve what we inherited from previous generations and pass it safely to those who will come after us. The pressure of an ever-growing population in terms of the resources, networks, supplies and services necessary to cover their needs is proportionately increasing. Cities have assumed this role of accumulation, especially during the past three centuries. Being similar to countries or to individuals, cities behave like living organisms: they grow and shrink, they affect their environment. They also interact, compete, assist others or merge into mega-scale metropolitan zones. Cities keep changing, by adapting to external conditions or by attempting innovations such as the eradication of their historical cores. They also give birth to suburbs through urban sprawl. Today, many cities keep repeating similar mistakes and keep experiencing the challenges of the past. Three years ago, a similar benchmark regarding the global population was met: half of the world’s people were now living within urban areas. This was undoubtedly a critical point that emphasised the pressure being placed on all systems and urged us to come up with solutions. Cities across the world shelter more than half of the human population and occupy almost 2 per cent of the planet’s land surface. They concentrate 80 per cent of humanity’s economic output, account for 70 per cent of global energy consumption and 75 per cent of carbon dioxide emissions. So the hypothesis is clear: an increased population leads to larger cities and more demand for energy and resources — sometimes beyond the capabilities of some of those cities or their countries — at the expense of the whole planet. Even though several cities have achieved a balance between their growth and their environmental impact by achieving high standards of social well-being — most keep following worrying trends. Furthermore, even though cities, people and countries are subject to artificial restrictions, their impact zones transcend borders and affect each other as a single system. To address the climate change issue, all countries — and even all cities must act collectively and no one can afford to consider themselves an outsider. Equally to India overtaking China at the top of the population list for countries, Mumbai is also projected to pass Tokyo, Jakarta and Mexico City by 2050, followed not only by other Indian cities but African ones as well. The provision of housing, work and systems that will support healthy and socially just living conditions while maintaining a proper balance with the environment becomes of paramount importance. Similar to some of those cities mentioned, those in places such as the Gulf would be well-placed to respond to those calls and even lead by example against extreme climatic conditions and at-risk natural systems, such as heating and rising oceans, desertification, water depletion and wildlife extinction. They should continue investing in education and science, and open up even more to change and inclusion. Only when cities around the world fully realise these values will sustainability become something more than just numbers, indicators and ticked boxes: it will reinstate humans as an integral part of a larger system, of planet Earth.