Land takes up just 29% of the Earth’s surface. Of that, some areas are uninhabitable [e.g. hot/cold/rocky deserts], some are used for agriculture, while others are populated by vegetation, freshwater bodies, or humans.
Worldwide, urban land expansion is happening at a faster rate than urban population growth rates. This shows that as individuals move further away from city centers, larger houses and neighborhoods are built. This corroborates the idea that someone living downtown is likely taking up less room than others who live near the city limits. Studies have attempted to quantify this “urban sprawl” and have found that in some regions, urban area growth rate is over twice the urban population growth rate.
By 2050, 68% of humans are expected to live in urban areas, up from 55% 2018. Planning for this increase without contributing to urban sprawl will be important to mitigate land use conversion, climate change, and biodiversity loss.
In 2019, farmland [i.e. crop and livestock farms] occupied roughly 50% of the Earth’s habitable land area. As food production booms, this percentage will increase if our unsustainable food systems remain unchanged. That’s problematic since agricultural expansion competes against other land uses that are also important [e.g. ecosystems].
However, since food production is an immediate necessity, land use conversion of natural ecosystems often occurs to allow agricultural expansion. It’s estimated that agriculture was responsible for around 73% of tropical deforestation worldwide from 2000-2010 [with tropical deforestation accounting for roughly 95% of total deforestation].
Unfortunately, this type of land use conversion releases billions of tonnes of GHGs into the atmosphere every year. It also induces severe habitat loss, which leads to significant biodiversity loss.
Human Land Space
Human infrastructure doesn’t occupy that much land compared to agriculture. Even with almost 8 billion people on Earth in 2022 [projected to peak at 9.73 billion by 2064], only 1% of habitable land is considered “urban and built-up”.
Regardless, humans need shelter to live in humane conditions. And if the global population is expected to grow by roughly 2 billion people in less than 30 years, cities are going to have to expand.
Unfortunately, many countries are already unable to secure good living conditions for their populations. In 2020, an estimated 1.6 billion people lived in inadequate housing conditions [adequate includes a minimum of the following elements: legal security of tenure, affordability, habitability, accessibility, proximity to services, availability of infrastructure, and cultural adequacy]. That was equivalent to over 20% of the global population at the time.
Urban Expansion and Sprawl
In some countries, urban expansion is synonymous with urban sprawl. Alas, this ‘uncontrolled’ form of urban expansion has negative impacts on the environment.
First, urban sprawl leads to the continuous construction of new homes far away from city centers. Consequently, it also leads to the expansion of roads, water mains, electricity lines, gas pipes, sewage, and anything else that modern homes require. These infrastructure needs are costly and material/energy-intensive.
Additionally, greater distances to city centers increase transportation energy use. As such, without a relatively ‘cheap’ and abundant energy source like gasoline, urban sprawl wouldn’t be possible [considering EVs are still rare]. City planning will have to change if we intend on reducing energy consumption and associated emissions.
Lastly, if cities expand, then they’re expanding into a previously occupied area. Most of the time, that ends up being forests, grasslands, or other green ecosystems. Urban expansion caused roughly 10% of tropical deforestation from 2000-2010 [with tropical deforestation accounting for roughly 95% of total deforestation].
To avoid spreading into green ecosystems, depleting resources, and releasing GHGs, governments can adopt more efficient housing strategies.
Policies that disincentivize multiple home ownership in urban areas can effectively reduce the amount of vacant homes in cities. With more of these vacant properties back on the market, more individuals will be able to find homes in urban areas, instead of purchasing houses that contribute to urban sprawl. Disincentivizing the ownership of large houses can also densify cities.
Additionally, governments can review zoning bylaws and incentivize the construction of apartment buildings. Building higher, as opposed to larger, can allow growing cities to maintain their current land use. Accelerating densification through policies that favor apartment buildings can avoid many of urban sprawl’s negative impacts.
To grasp how effective apartment buildings can be, imagine a mid-rise apartment building that can accommodate 100 units, while only occupying the land area of 4 standard houses. In this scenario, each unit ends up occupying just 4% of the area of 1 standard house. That saves a lot of land compared to the 100-house alternative. All we have to do is expand higher instead of spreading horizontally.
Note that a few studies have found that high-rise apartment buildings can often be more energy-intensive than their low/mid-rise counterparts – especially when high-rise buildings don’t densify as much as they could [e.g. for luxurious apartments]. So building a city of skyscrapers to protect the environment might not be the best thing to do. Experts will ultimately have to find the right balance between lower land use footprints and carbon footprints.
Apartment buildings that replace suburbs in urban areas can create ‘free space’ that cities can develop into enjoyable areas. Notably, there can be more room to set up urban green areas, where vegetation can mitigate air/water/noise pollution and improve water management. Cities can use these co-benefits to save hundreds of millions of USD every year. The more green spaces there are, the more a city can save.
Additionally, increasing urban density reduces material/energy consumption. Examples feature lower gasoline consumption due to shorter commutes [and increased public transit use], less pumping required for water and natural gas transport, and less electricity losses. Without forgetting the enormous quantities of metal, asphalt, and concrete saved by not extending roads, water mains, gas pipes, and electricity transmission networks.
Higher population density also facilitates sharing, which can reduce material/energy consumption even further. For example, apartment buildings can have shared laundry machines, game consoles, and even vehicles.
Urban sprawl is an inefficient solution to an important problem. To mitigate the impacts of growing urban populations, governments can push for urban densification instead. Improving policies and zoning bylaws can incentivize densification and apartment-style living. Governments can also take advantage of densification’s co-benefits to develop urban vegetation.
On the natural side, farmland is encroaching on ecosystems. Land use conversion of natural areas to allow agricultural expansion induces significant biodiversity loss. Changing the current unsustainable food system will be key to limit agricultural land use.