Timon Eggenberg

With the knowledge we have about the climate change and the fact, that the trend of urbanization will not stop soon, it is not really a question if megacities can be sustainable, but rather how they will be sustainable.

Figure 1: The urban population and rural populations in millions and the urbanization rate over the past 70 and the next 30 years (Li, Ma, Cheng, van Genderen, & Shao, 2019).

Current situation and problems

People from the rural areas are moving to cities, hoping for education, healthcare, and jobs. The number of megacities is going to rise as well as the magnitude of this cities. Megacities are defined as cities with agglomeration where more than 10 million people live (cf. Siegel, 2019). Because these megacities will grow in inhabitants and in quantity the question that comes up is: “How can these megacities be sustainable?”
The SDG number 11 is: “Make cities and settlements inclusive, safe, resilient and sustainable”. In this blog post the focus is on the sustainability part of the goal eleven, because the challenges to be more inclusive and safer must be addressed in all place humans live. But in a place, where a lot of people live, the challenge to be sustainable rises with higher population. The extreme in high population today are the megacities. That’s why we primarily look at the challenges for a megacity to be sustainable.
So, we ask what special challenges the megacities face in terms of sustainability and how these challenges can be solved.
Air pollution is still one of the biggest problems in megacities. A major air pollutant, mostly in developing countries, are sulfur compounds, which have major impacts on the public health. But the main source of air pollution, even in cities in developed countries, is the photochemical smog (cf. Molina & Molina, 2004). But it’s not the same problem everywhere: In New Delhi, India, it’s a seasonal problem, where the reason for air pollution is the burning of the straw and stubble residue after a rice or a wheat harvest. Also how the city is built in general plays a major role to the air pollution problem (cf. Siegel, 2019).
One of the main sources of air pollution is traffic. Thus, solving this problem would have a positive impact on the air quality, as well as on other important factors (Molina & Molina, 2004), such as minimizing economic loss, energy waste and noise pollution (Li et al., 2019).
With a high population also comes a high demand on electricity. Adding to that, the consumption rate of high concentrated urban areas is disproportionally high (Smil, 2019). The problem here is obvious: How can the megacities be powered in a sustainable way? With energy production and megacities comes another problem: It is unsustainable and the consumption is inefficient (cf. Li et al., 2019).

 Solutions

There are several solutions to the air pollution problem, for example the prevention or reduction of emissions from manufacturing and industrial plants and the reduction of emissions from traffic. That could be achieved through using the newest filter technologies (cf. Siegel, 2019). As mentioned above, there are some factors shared by many of the megacities, but the situation must be evaluated for every single city. For example, the air pollution in New Delhi: One solution would be to educate the farmers that plowing the crop residue back in the soil is more sustainable than burning it and it can improve the nutrients concentration (Siegel, 2019).
There are also several approaches to solve the traffic problem. A case study from Beijing shows, that shared transportation can play an important role in mitigate traffic and environmental issues (Sun et al., 2018). Another approach is trying to develop the traffic in that way, that the time spent between door to door is less than half an hour. This could be achieved by fast subways or high-speed rail. The study gives the example between Beijing and Tianjin. Either way, there should be scientific traffic planning, so that there is a coordinated development in the megacities (cf. Li et al., 2019). One obvious solution to make the traffic greener and reduce the air pollution is the use of electric cars. But this would not really solve the fact that there still would be traffic congestions. Better public transport could be useful to solve that problem (cf.Molina & Molina, 2004). To power these electric cars or the public transportation, the demand for electricity grows, which leads us to the next problem of the megacities, the energy supply.
One key point in tackling the problem of the energy supply in megacities is decentralization: Instead of gaining the energy from large central stations and high voltage transmission lines, the electricity generation should be decentralized, on-site and small-scale (Smil, 2019). As mentioned earlier, the energy production and consumption in megacities is inefficient and with that approach, this loss can be avoided as well as the loss because of long-distance transmission. One part of decentralized electricity generation could be done with photovoltaic systems that are put on the roofs of the houses. The Obama administration in the United State made this a priority (cf. Li et al., 2019). But a projection shows, that in the most densely populated area in Tokyo, photovoltaic panels would provide only 20 percent of the average electricity needed (Smil, 2019). And this projection makes the extreme assumption, that there would be solar panels on every roof. So, putting photovoltaic panels on every roof is only a tiny piece to the whole solution. Other important points are the storage (Smil, 2019) and the off-peak supply (Li et al., 2019).

Conclusion

Summing up, some of the problems have been solved in the megacities of the more developed countries, for example the sulfur compounds concentration. This doesn’t mean that the problems disappear as the city gets more developed. The consumption rate of electricity for example, won’t just vanish as a city gets more modern. And while there is often more than one solution, the question is, how to solve a problem without creating a new one. The electricity consumption is again a good example: To solve the air pollution problem, one solution would be to replace conventional cars with electric cars. But then the demand for electricity would go up as well. So, it seems that tackling one problem is just creating a new one or making an existing one worse. But knowing that we as humans must achieve building sustainable megacities, we – more specific, the countries with megacities – still must put the effort into solving these problems,  However, one point seems to be certain: A megacity can only be sustainable if there is good planning and problem solving at the local level.

 References

Deren Li, Jun Ma, Tao Cheng, J. L. van Genderen & Zhenfeng Shao (2019) Challenges and opportunities for the development of MEGACITIES, International Journal of Digital Earth, 12:12, 1382-1395, DOI: 10.1080/17538947.2018.1512662

Li, D., Ma, J., Cheng, T., van Genderen, J. L., & Shao, Z. (2019). Challenges and opportunities for the development of MEGACITIES. International Journal of Digital Earth, 12(12), 1382–1395. Retrieved from https://doi.org/10.1080/17538947.2018.1512662

Molina, M. J., & Molina, L. T. (2004). Megacities and atmospheric pollution. Journal of the Air and Waste Management Association, 54(6), 644–680. Retrieved from https://doi.org/10.1080/10473289.2004.10470936

Siegel, F. R. (2019). Cities and Mega-Cities. SpringerBriefs in Geography.

Smil, V. (2019). Distributed generation and megacities: Are renewables the answer? IEEE Power and Energy Magazine, 17(2), 37–41. Retrieved from https://doi.org/10.1109/MPE.2018.2884112

Sun, L., Wang, S., Liu, S., Yao, L., Luo, W., & Shukla, A. (2018). A completive research on the feasibility and adaptation of shared transportation in mega-cities – A case study in Beijing. Applied Energy, 230(May), 1014–1033. Retrieved from https://doi.org/10.1016/j.apenergy.2018.09.080