Updated: Aug 11
Population, Urbanization and Climate Change
Keywords: Population Growth; Urbanization; Climate Change; LECZ; Megacities; Bangladesh
“The ultimate intelligence of our species will be determined by whether we face our population issue and get it under control, or continue to sweep it under the rug because it’s an uncomfortable conversation. The future of life on Earth depends on us doing the former.”
- Leilani Munter
The year 2015 signaled a remarkable confluence of events in global policy, with three landmark UN treaties being published. These were the Sustainable Development Goals, the Disaster Risk Reduction, and the Paris Climate Accord (Sofia et al. 2017). The junction of these agreements acted, respectively, like a quantum leap for raising awareness of the links in the triad of population dynamics (contemplating the rate of growth, migration, density, and urbanization) (Donner & Rodríguez, 2008), landscape (spatial development, territorial vulnerability) and climate (e.g. flooding, erosion, salt intrusion, sea-level rise and extreme climate events).
The combination of all of these unfavorable circumstances has been building up to what I consider to be a perfect storm. Evidently, not in the sense that it is praiseworthy or desirable, but that the mixture of these components is engendering a devastating condition. Owing to this, I will be arguing under the aegis of mostly an adaptive angle (Bendell, 2018) since mitigation strategies relative to spatial planning are almost literally, out of my depth, and because I hold that the scale of anthropic impact has been so tremendous that we ought to focus on the reduction of harm. Still, in the mitigation department, I intend to convince the reader that without addressing the continuous flow of a growing population, more people will be put in harm’s way and the degradation of natural areas will continue despite our best intentions.
Regarding the mitigation of further GHG emissions, this will be my first and last exhortation on the topic. Obviously, not because I don’t deem it relevant, but by virtue that I hold that our on current - and almost global - thermo-industrial civilization is likely incapable of maintaining itself without growth and the invariable waste management problem arising from it, that we have come to call GHG emissions (Rees, 2019). Moreover, we have squandered decades on non-abiding agreements and the dominating mantra is still further development and growth to solve the problems created mostly by a burgeoning affluent society. If nothing else, this has left me extremely cynical to the prospect that we will turn this ship around willingly. Still, we need to sail these rough waters to get somewhere, with the destination of this work focusing on what can be considered one of the most threatened areas of the planet, Low-Elevation Coastal Zones (LECZ).
Accordingly, LECZs are defined as a contiguous area along the coast which is less than 10 meters above sea-level (UNSD, 2009). These zones converge all of the aforementioned elements which are examined in this document, that of an expanding demography, which in turn is altering the arrangement of the land, all the while becoming ever more vulnerable to hydrological extreme fluctuations enhanced by climatic factors (Crawford, 2007; Barbier, 2015).
This assemblage of circumstances is heightened in relevance and emergency when considering that LECZ have been described as the ‘frontlines of climate change,’ seeing that 15 developing nations contain roughly 90 percent of the world’s rural poor (Barbier, 2015). Coupled with this, the UN (2017) estimates that roughly 600 million people are currently living in coastal zones that are less than 10 meters above sea level, while Neumann and colleagues (2015) put this number closer to 625 million. As the human population is only foreseen to continue to increase by several billion (PRB, 2020), it is expected that much of this growth will be concentrated in low-elevation coastal zones, seeing that they have attracted humans since time immemorial for their natural resources and points of marine trade and transport, but also because urban areas are expanding at their fastest rate in the LECZ (Seto, Fragkias, Güneralp & Reilly, 2011).
Increasing population growth and its nexus with environment pressure and food security (Pimentel, Huang, Cordova & Pimentel, 1997; Commoner, 1991; Faisal & Parveen, 2004; Myers, 1992; Ripple et al. 2017; Crist, Mora & Engelman, 2017), points to substantial and serious considerations when taking into account all the resulting migratory movements [due to demographic and climate change (Hugo, 2011), and economic policies and incentives (Seto, 2011)] and all its repercussions for political stability, and inter-state conflict, resource scarcity and saturation of infrastructures and services (Curtis & Schneider, 2011; Pradhan, 2008; Bilsborrow, 1992). Not to mention, the pressure for so many people to find a suitable place to settle is so great, that migration into coastal hazardous zones continues unabated despite the clear risk for making one’s home there (De Sherbinin, et al. 2012).
Correspondingly, the aforesaid population dynamics have been declared as one of the most decisive factors in humanity’s mounting exposure to disasters with calamitous impacts (Donner & Rodríguez, 2008), especially in LECZ which are more densely populated than the backcountry (Small & Nicholls, 2003), while exhibiting higher rates of urbanization, population growth and in-migration (McGranahan, Balk & Anderson, 2007; Hugo, 2011; Neumann, Vafeidis, Zimmermann & Nicholls, 2015).
For these reasons, population dynamics will take center stage in this analysis of the relationship between spatial planning and climate. To understand this nexus, I shall now delve into the role of urbanization and megacities in expediting environmental deterioration and human vulnerability.
In his book, Scale: The Universal Laws of Life, Growth, and Death in Organisms, Cities and Companies, Geoffrey West (2017) argues that:
"The future of humanity and the long-term sustainability of the planet are inextricably linked to the fate of our cities [with] rapid urbanization and accelerating socio-economic development having generated multiple global challenges. […] given that the overwhelming majority of human beings will be urban dwellers by the second half of this century, many megacities of unprecedented size will appear.”
By all means, a settled urban ‘ecosystem’ firmly diverges from a natural or agricultural ecosystem. These urban agglomerations are distinguished by the human-altered and recurrent artificial landscapes with significant anthropogenic disturbances such as environmental pollution, soil sealing, and waste accumulation (Vasenev et al. 2018).
Owing to this unprecedented concentration of human beings in cities and megacities throughout the globe, particularly in LECZ, population growth, in-migration, and spatial development become significant and inescapable drivers of environmental decline in coastal landscapes through the increased conversion of land and pollution (Patterson & Hardy, 2008; Crossland et al. 2005), be it via agriculture and water management (Gowing, Tuong & Hoanh, 2006; Stoate et al. 2009; Bala & Hossain, 2010), or by way of urban development (Tibbetts, 2002; Creel, 2003) and other anthropogenic activities (Vieiro, Roder, Matticchio, Defina & Tarolli, 2019).
The scale of population growth and migration is at its most extreme in African and Asian coastal cities, with some of these cities in the tropics having duplicated their populations in about a decade (Tibbetts, 2002). Correspondingly, the adversities and obstacles for the spatial planning of these cities in a world constantly ravaged by climate change will be overwhelming (Kennedy et al. 2015). Furthermore, most of the world’s megacities are situated in coastal zones (Brown et al, 2013). The increased interest in coastal zones will most likely continue to materialize into rapid population growth in these areas, with research deducing that by 2030 the global human population inhabiting LECZ could expand to 880 million, whereas by 2060 it could reach more than 1.3 billion, what would signify an enlargement of 763 million additional people compared to the situation in 2000 (Neumann et al, 2015).
In essence, population and economic growth are both acting in tandem as agents of deterioration for coastal ecosystems. Population growth and immigration are mainly operating through the expansion of urban sprawl (pattern of unrestrained development around the periphery of a city) which ends up converting natural areas to built-up land (Crawford, 2007; Beck, Camarota & Kolankiewicz, 2003; Kolankiewicz, Beck & Manetas, 2014; Skog & Steinnes, 2016; Ma, Lu & Sun, 2008), while economic growth and increases in per capita affluence translate into infra-structure megaprojects that conquer and invade the natural world (Alamgir et al. 2019a; Sloan et al. 2019; Laurance, 2019; Ascensão et al. 2018), by way of seemingly innocuous means such as roads (Laurance & van Oosterzee, 2019a; Alamgir et al. 2019b; Kleinchroth, Laporte, Laurance, Goetz & Ghazoul, 2019; Mason et al. 2017) fences (Laurance & van Oosterzee, 2019b), or even land reclamation projects which end up becoming profoundly calamitous ecological disasters.
As this document is written, seas all over the globe are being conquered to give way to emerging cities, with mega projects being spearheaded by Malaysia (Forest City in Johor) (William, 2016; Ourbis & Shaw, 2017; Schneider, 2018); the New Manila Bay – City of Pearl – in the Philippines (Salikha, 2018); Cambodia is reclaiming land (Kawase, 2017); Dubai is creating many artificial islands (Wainwright, 2018); Sri Lanka’s Colombo Expansion (Ranasinghe, 2012; Xinhua, 2019a; 2019b); around a quarter of modern Singapore is the product of this sea/land conversion (Nation Library Board, 2019; Harios, 2019), and of course, China has been conquering an area the size of Singapore every year from 2006 to 2010 (Shepard, 2018).
It must be remembered that for example in the case of Forest City in Malaysia, these urban megaprojects are reclaiming natural areas such as mangroves and seagrass meadows [the largest of its kind in the country (Ourbis & Shaw, 2017), and a refuge for some of the most diverse marine wildlife (Nordlund & Gullström, 2013; Henderson, Gilby, Lee & Stevens, 2017), as well as indicators of the coastal ecosystem’s health (Marbà et al. 2013; Heithaus, Wirsing, Frid & Dill, 2007), causing numerous and understudied environmental impacts, as Joseph Williams argues in his Master’s Thesis submitted to the Department of Urban Studies and Planning for the MIT (2016). Still, we should be mindful that the rising pressure from this expansion into the sea is directly correlated with a growing human population that is also acquiring more purchasing power (Kharas, 2017), demanding luxurious accommodation and having a greater environmental footprint overall (to the detriment of the Kuznets curve) (Aydin, Esen & Aydin, 2019; Bradshaw & Di Minin, 2019).
With this in mind, there is also a need to examine the growth of megacities, propelled by the above-named drivers. This is not to say that the conversion of natural areas to built-up land is not occurring outside of the realm of megacities, much on the contrary, as urban sprawl appears to be unraveling at its fastest rate in middle-sized and small urban areas, creating (and eventually consuming) the peri-urban regions (Ford, 1999; Cobbinah & Amoako, 2012; Shahraki et al. 2011; Jat, Garg & Khare, 2008; Sudhira, Ramachandra & Jagadish, 2004; Weng, 2001). Come what may, the uncontrolled phenomenon of the growth of urban sprawl is associated with the reduction of the physical order of places, which leads to economic inefficiency and inappropriate land use management as urbanized areas widen and the peri-urban is impacted (Cobbinah & Amoako, 2012).
Additionally, it is also worth noting that urban sprawl is a process that is shared by developed and developing countries alike, although their causes can vary (Shahraki et al. 2011). For instance, in nations with higher GDP per capita, it is usually consumer preferences that drive development, through means such as real estate (Chen, Liu & Tao, 2013; Puga, 1998) (this was already alluded to with the land reclamation projects, which are being launched by developed countries or with the investment of China), although the motivations in the developing world are still underexplored (Shahraki et al. 2011; Henderson, 2002). At any cost, for this work, it was decided that a focus on megacities would be more advantageous to the case-study analysis of the megacity of Dhaka, Bangladesh, and a reference to peri-urban expansion would suffice to enrich the argument.
Megacities, specifically, are simply defined in urban geography as having a population that exceeds 10 million people (Pelling & Blackburn, 2014), but even though, currently <4% of the total world’s population inhabits a coastal megacity, their environmental impact due to rampant development, elevated population densities and high consumption rates (e.g. Shanghai, Tokyo, New York, but excluding Dhaka and others with similar per capita affluence) has been well described (Sekovski, Newton & Dennison, 2012). It should be noted that in 1950 only two metropolises were accomodating more than 10 million people (New York and Tokyo), while in 1980 Mexico City and São Paulo were added. Comparatively, by 2010, 21 megacities already existed (Sobrino, 2013), and in 2018 the number had skyrocketed to 33 and in 10 years, that total might be closer to 40 (Razvadauskas, 2018).
To this effect, it should be added that with an extra 2.5 billion people inhabiting urban areas by 2050, projections estimate 68 percent of the human population to reside in cities by the same date [compared to 30 percent in 1950 and 55 percent in 2018 (UNDESA, 2018)]. Equally important, the scientific literature is pointing to higher ecological footprints in cities compared with averages of their respective countries (Global Footprint Network, 2020; 2015; Wackernagel et al. 2006), to this effect, we should remain attentive to the possibility that although cities have enormous potential to ameliorate environmental damage, they might never become sustainable (Rees & Wackernagel, 2008), because, in thermodynamic and biophysical terms, they act as entropic black holes to other more productive areas (Rees, 2011), since they generally consume more energy than they can provide (Vasenev, 2016).
As an illustration, already at the end of the previous century, it was calculated that London required a territory 120 times bigger than the area of the city (also called Lebensraum (Abegão, 2018 p. 236)], while Vancouver (ranked among the top in quality of life) requires an area ranging between 180 and 319 times its nominal area (Bauman, 2013; Devuyst, Hens, de Lannoy & de Lannoy, 2001). Furthermore, in terms of ecological footprint each Athenian today demands about 4.84 global hectares (gha) compared with an average for Greece of 4.41 gha and a sustainable biocapacity of 1.5 gha. This means that Greece is in overshoot (Earth Overshoot Day, 2020; Catton, 1982). The same pattern has been described in other Mediterranean countries and their corresponding cities, such as Barcelona in Spain (4.52 gha, 4.05 gha respectively with biocapacity of 1.4 gha) or Cairo in Egypt (2.85 gha, 1.79 gha respectively with biocapacity of 0.5 gha).
To a degree, the first link between population dynamics and pressures in spatial planning in LECZ has been described. However, there is still a need to contemplate the major implications of climate change on LECZ as well as from anthropogenic activities with the intent of shaping the landscape with modifications, under the aegis of 'development.' One of the major threats affecting megacities in low-elevation coastal zones is the sea-level rise (SLR).
With regards to SLR, it has been estimated that the fastest rate of increase of the last 2800 years has been observed between 1901 and 2010 (UN, 2017), with the most up-to-date science pointing to a yearly rising of about 3-4 mm (Watson et al, 2015; Yi, Sun, Heki & Qian, 2015) due to ocean warming and the melting of ice (Vitousek et al. 2017). Considering this, an estimated two-thirds of the world’s cities with populations above 5 million inhabitants are foreseen to be threatened by advancing sea levels (UN, 2017).
In terms of its impacts, SLR is known to cause coastal erosion, inundations, storm floods (Yin, 2020), tidal waters encroachment in rivers and estuaries, the adulteration of freshwater reserves and the contamination of food crops, as well as other ecological repercussions such as loss of habitat (e.g. nesting beaches) and displacement. All in all, sea-level rise is considered a significant risk to coastal regions (particularly low elevation ones) and communities inhabiting and depending on resources on those places (UN, 2017), with these conditions having been meticulously studied in countries like Bangladesh (Karim & Mimura, 2008; Chen & Mueller, 2018), Italy (Viero, Roder, Matticchio, Defina & Tarolli, 2019; Pijl, Brauer, Sofia, Teuling & Tarolli, 2018), China (Liu et al. 2015), Portugal (Coelho, Silva, Veloso-Gomes & Taveira-Pinto, 2009) and in regions of Africa, Asia and South America (Balk et al. 2009).
Coupled with the impetus of the seas, human interventions such as deforestation, confinement of rivers, agriculture and urbanization have affected flood dynamics under climate change scenarios (Blöshchl et al. 2017), which are known to exacerbate hydraulic hazards such as high-impact flood events (Vieiro et al. 2019). Identically, one can’t make the case that this hydraulic risk in lowlands and coastal zones is the sole byproduct of fixed environmental characteristic, as these territories are complex and dynamic systems subject to change, which interact with climatic forcing and socio-economic conditions (Anthony, Marriner & Morhange, 2014; Minaei, Shafizadeh-Moghadam & Tayyebi, 2018; Pijl, Brauer, Sofia, Teuling & Tarolli, 2018; Sofia, Roder, Fontana & Tarolli, 2017).
For instance, when Hurricane Harvey made landfall on the US’s southern states in August 2017, a study published in the journal Environmental Research Letters by Geert Jan van Oldenborgh and colleagues (2018) claimed that Harvey would have released 15 percent less water in the form of precipitation if not for the influence of climate change. Moreover, the Expert Team on Climate Impacts on Tropical Cyclones from the World Meteorological Organization (WMO) concurs that rainfall rates linked with Harvey were in all probability made more intense by anthropogenic climate change. Demonstrably, it is due to the water vapor that is held in the atmosphere as a consequence of climate warming (Knutson et al, 2017).
In other words and to all appearances, human-induced climate change increased Harvey’s total rainfall around Houston by at least 19 percent, with the best appraisal of 37 percent; and that climate change increased flooding by roughly 15 percent as well as increasing the odds of witnessing such an extreme event from 1.5 to 5 times, with the baseline being pre-industrial times (Irfan & Resnick, 2018; Risser & Wehner, 2017; van Oldenborgh et al, 2017). However, there is more to this story.
Notably, the sheer aggregate of human life and urban development (Zhang, Villarini, Vecchi & Smith, 2018; Holmes, Shao, Zhao & Gao, 2018) that has surged in Houston, the country's fourth-largest city and also the fastest-growing city in the United States with its 2.3 million residents (US Census Bureau, 2017) - 6.5 million, when taking into account the greater Houston metropolitan area (Houston Facts, 2016) - set the city on a collision course with a disaster with much higher consequences (human and economic) than it would have otherwise had (Starkey, 2017).
On this account, Samuel David Brody, director of the Centre for Texas Beaches and Shores at Texas A&M Galveston assessed the state of affairs impacting Houston:
"Houston has a large amount of pavement - impervious surface - put down in a very low-lying, flat area that experiences heavy rainfall events. I tell my students that the problem is complicated; there are lots of underlying factors. There are physical conditions. There's environmental change increasing these heavy rainfall events. There's the sea-level rise and changing temperatures. All of those small, slow-moving gears are part of this overall problem. The bigger gear moving much faster is human development - the built environment. Houston added 100,000 people last year alone. That sets us up for this potential catastrophe" (Starkey, 2017).
When considering the anthropogenic activities that have utterly transformed the landscape of Houston, and that rapid development and population growth are leading to the severe degradation of crucial habitats such as wetlands, coral reefs, sea grasses and estuaries (Tibbetts, 2002), The New York Times also weighed in on the necessity to face ecological limits in the piece A Storm Forces Houston, the Limitless City, to Consider Its Limits (Fernandez & Fausset, 2017):
“Though its breakneck development culture and lax regulatory environment have been lauded for giving working people affordable housing - and thus a shot at the American dream - many experts and residents say that the developers’ encroachment into the wetlands and prairies that used to serve Houston as natural sponges has inevitably exacerbated the misery that the city is suffering today [...] The post-Harvey rebuilding drama here is bound to unfold as a frontier nation increasingly faces up to limits - as southern and western cities mature, as resources are strained by a growing population, and as climate change, exacerbated by Houston’s signature industry, threatens bigger, wetter, ever-more-dangerous storms [...] Harris County, which includes Houston, experienced the highest annual population growth of any county in the United States in eight of the last nine years, according to census data (US Census Bureau, 2017).”
Similarly, the Washington Post’s Houston’s ‘Wild West’ growth (Boburg & Reinhard, 2017) reinforces the argument that the scale of development and population growth observed in the city, greatly contributed to the devastating events of 2017.
“As the population grew, the city expanded, covering fallow land that had served as a natural sponge (figure 3). Between 1992 and 2010, 30 percent of the surrounding county’s coastal prairie wetlands were paved over, according to a 2010 report from Texas A&M (Jacob, Pandian, Lopez & Biggs, 2015). Projects to widen the bayous and build thousands of retention ponds for excess water have not kept pace with the new rooftops, roadways, and parking lots needed to accommodate about 150,000 new residents a year, experts say.