Population growth and urbanization

It is generally agreed that population growth, together with an increase in average per capita incomes, will result in higher pressure on natural resources and biodiversity (e.g. Foley et al., 2011).

Feeding, housing and meeting the other needs of more than 9 billion people in the coming two to three decades will exert pressures on ecosys-tems worldwide.

People living in cities now outnumber those living in rural areas (United Nations, 2014a).

Projections indicate that population growth in cities and small rural towns, along with the number of people migrating from rural to urban areas, will continue to increase. Urban popula-tion growth rates actually decreased from around 3 percent in the 1960s to around 2 percent in the five years to 2016.³ However, the percentage of the world population living in urban areas grew from 33 percent to 54 percent over the same period, or from 1.01 billion to 4.2 billion

3 World bank staff estimates based on the united nations Population Division’s World urbanization Prospects:

2014 revision.

table 3.3

Number of countries reporting negative, neutral and positive effects of drivers of change on the diversity, availability and knowledge of wild foods

Negative Neutral Positive

Driver Diversity Availability Knowledge Diversity Availability Knowledge Diversity Availability Knowledge

Population growth and urbanization 29 37 22 9 6 8 1 2 4

Markets, trade and the private sector 18 20 10 9 6 6 11 16 21

Changing economic, sociopolitical and cultural factors 19 18 9 8 8 8 12 14 18

Climate change 31 35 13 7 5 13 3 2 2

natural disasters 22 29 11 8 6 11 2 2 3

Pests, diseases and invasive alien species 34 40 15 6 2 9 2 2 2

advancements and innovations in science and technology 5 8 3 9 9 6 20 24 28

Changes in land and water use and management 32 41 21 8 5 10 5 6 7

Pollution and external inputs 29 35 13 8 5 9 1 1 6

Overexploitation and overharvesting 36 45 18 6 4 10 1 2 5

Policies 9 9 4 11 7 8 23 34 26

Notes: The numbers in the table represent counts of country reports. Sixty-one out of 91 country reports provided information.

Source: Country reports prepared for The State of the World’s Biodiversity for Food and Agriculture.

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the state of the WorlD's bioDiversit y for fooD anD agriculture

in absolute terms (United Nations, 2014a, 2018).

It has been predicted that the figure will rise to 68 percent by 2050 (United Nations, 2018). The global rural population is now close to 3.4 billion and is expected to rise slightly and then decline to around 3.1 billion in 2050 (ibid.). Urban popula-tion growth will, therefore, not mean an “empty-ing” of the countryside in the near future, at least at global level. At regional or local levels, however, there are already cases of rural depopulation, fuelled largely by outmigration to neighbouring, or more distant, town or cities, or to other coun-tries (e.g. Gray and Bilsborrow, 2014; Chen et al., 2014). This often leads to increasing involvement of women in the management of agricultural holdings (e.g. Agarwal, 2015; FAO, 2011e) (see also Section 3.8). Out-migration from rural areas can be permanent or temporary, involve people of various social strata and education levels, and often results in an inflow of remittances to family members who remain. The inflow of remittances may represent up to 30 percent of gross domestic product in some countries (World Bank, 2018).⁴

As noted in the introduction to this chapter, urbanization can affect biodiversity in many ways.

Globally, urban development is a significant direct driver of land-use change, deforestation and habitat fragmentation (Elmqvist et al., eds., 2013).

However, it also has numerous effects on (inter alia) lifestyles and consumption patterns, social and political attitudes, and the organization of production and supply chains, all of which can have knock-on effects on biodiversity, on a range of scales (ibid.). For example, as people move to cities they tend to depend increasingly on purchased foods, often from a few supermarket chains (Macfadyen et al., 2015). They often also tend to lose ties with rural areas and rural foods, and increasingly opt for processed foods rather than fresh foods (Popkin, 2017). While supermarkets and other modern retailers can make a more diverse diet available and accessible to more people, they can also encourage

4 World bank staff estimates for 2016 based on international Monetary Fund balance of payments data, and World bank and OeCD GDP estimates.

the consumption of energy-dense, nutrient-poor, highly processed foods and reduce the ability of marginalized populations to purchase the food needed for a high-quality diet (Hawkes, 2008). This often has negative consequences for nutrition (see Section 2.6). Urban consumption patterns are also associated with a greater proportion of food going to waste (Parfitt, Barthel and Macnaughton, 2010).

Demand for standardized foods can lead in turn to a decrease in the diversity of the crops and animals raised in food and agricultural systems (see also Section 3.3.2). However, demand from urban consumers can also help promote “BFA-friendly” approaches such as organic agriculture (Seto and Ramankutty, 2016) or the maintenance of non-mainstream species, varieties and breeds of crops and livestock (FAO, 2013g; Lamers et al., 2016). Moreover, trends in consumption and retail-ing are more advanced in some countries than others. Urban food systems in developing counties often remain complex and diverse, with traditional outlets such as wet markets, street and mobile vendors still playing a major role (Crush, 2014) and substantial amounts of food being produced within the boundaries of cities (Orsini et al., 2013).

The impacts of dietary changes on BFA are further discussed in Section 3.3.3.

Human population growth and the resulting industrialization, agricultural intensification and urbanization are considered to be among the main global drivers of degradation of aquatic eco-systems (Verdonschot et al., 2013). Infrastructure development associated with urbanization affects water quantity and quality, changes river chan-nels, destroys habitats and habitat connectivity and favours the spread of invasive species (Speed et al., 2016). Pressures on aquatic ecosystems, especially rivers, are expected to increase (ibid.).

Population growth is also driving other threats to aquatic BFA, including overharvesting, pollution (including sediment loading caused by coastal development) and detrimental land and water use associated with touristic developments (United Nations, 2014a).

The impacts of population growth and urban- ization on ecosystem-service provision as reported

by countries are summarized in Table 3.4. In nearly all production systems and for nearly all ecosystem services, negative impacts are by far the most frequently reported. Countries report a diverse range of different impacts associated with this driver. Some emphasize the effects of habitat destruction linked to the expansion of towns and cities. For example, Morocco reports that urbanization is one of the most serious threats to its biodiversity. It notes that the rapid expansion of human settlements into areas that are rich in BFA and the removal of sand and rocks

from sites such as coastal dunes and wadi beds⁵ for use in construction are resulting in the loss of habitats and the species they shelter. China notes that since the late 1950s urbanization and the rapid development of industry, along with population growth, have led to ever-increasing discharge of industrial wastes, municipal sewage and garbage, including the disposal of garbage and solid wastes in farmland.

5 a wadi is a valley or streambed that contains water only during the rainy season.

table 3.4

Reported effects of population growth and urbanization on the provision of regulating and supporting ecosystem services, by production system

Production systems (PS)

Effects of population growth and urbanization on ecosystem services

Pollination Pest and disease regulation Water purification and waste treatment Natural-hazard regulation Nutrient cycling Soil formation and protection Water cycling Habitat provisioning Production of oxygen/ gas regulation

livestock grassland-based systems - - -

-livestock landless systems - - -

-Proportion of countries reporting

the Ps that report any effect of the

driver (%)

naturally regenerated forests - - -

-Planted forests - - -

-self-recruiting capture fisheries - - -

-Culture-based fisheries - - - 13–20

Fed aquaculture +/- - - 21–27

non-fed aquaculture - - - ^28–34

irrigated crop systems (rice) - - - ^35–41

irrigated crop systems (other) - - -

-rainfed crop systems - - -

-Mixed systems - - -

-Notes: Countries were invited to report the effects (positive, negative or “no effect”) of this driver on the provision of each ecosystem service in each production system. If 50% or more of the responses for a given combination of production system and ecosystem service indicate the same trend (positive [+], negative [-] or “no effect” [0]) then this trend is indicated in the respective cell of the table. In other cases, mixed effects (+/-) are indicated. The colour scale indicates the proportion of countries reporting the presence of the respective system that report any effect of the driver (positive, negative or “no effect”) on the provision of the respective ecosystem service. See Section 1.5 for descriptions of the production systems and a discussion of ecosystem services. Analysis based on a total of 91 country reports.

Source: Country reports prepared for The State of the World’s Biodiversity for Food and Agriculture.

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A number of countries emphasize the various ways in which population growth is driving expansion of the agricultural frontier and greater exploitation of natural resources. For example, Ecuador, one of the most densely popu-lated countries in Latin America, reports that the high density of the rural population is increasing local demand for resources and leading to the occupation of land that is not suitable for use for food and agriculture and that this is threatening the survival of wild species. Ethiopia notes that growth of the population has led to expansion and intensification of land use, overutilization of biological resources, increasing use of mar-ginal lands and the breakdown of traditional resource-management systems. These changes are reported to be putting pressure on all eco-system services and all the country’s biodiversity, including impacts on the availability and diver-sity of wild foods and on the maintenance of associated traditional knowledge.⁶ Zimbabwe mentions that human populations have been encroaching on previously unused habitats such as wetlands in an effort to escape the effects of drought, poverty and climate change and that this has led to the degradation of the affected ecosystems. Countries also note impacts on aquatic ecosystems, both via the effects of the increasing demand of growing populations for fish and other aquatic products and via the effects of pollution and infrastructure development.

Several countries mention the effects of migra-tion out of rural areas. For example, Ecuador notes that rural migration to urban centres is more common among men than among women, and is permanent, i.e. the migrants do not return. It further notes that this has led to an increasing pro-portion of women and elderly people in the rural population and in turn to the abandonment of cropping systems to make way for pastures and live-stock, as these require less labour. This is reported to have led to a decline of crop genetic diversity.

Several country reports from Europe note that the

6 the report cites Kelbessa et al. (1992), addis (2009) and asfaw (2009).

abandonment of farming areas can have negative consequences for some components of biodiversity.

Norway, for example, reports that the decline of grazing and haymaking on more marginal land is leading to forest expansion and that this is threat-ening a number of rare grassland species.⁷

Several countries report that urbanization and population growth, and associated infrastructure development and economic activities, are threats to marine biodiversity and aquatic resources. For example, Spain reports that increased coastal development due to tourism has affected pop-ulations of Neptune grass (Posidonia oceanica), a key Mediterranean seagrass species. In Europe in general, offshore wind parks, sand and gravel extraction and gas and petroleum pipelines are considered to be particularly damaging to marine flora and fauna, depriving fisheries of key fishing grounds and many species of their habitats. Among Latin American countries, Argentina reports that urban infrastructure development is affecting wet-lands in its Delta region – damaging the region’s traditional productive agroecosystems, dimin-ishing their capacity to supply ecosystem services such as flood control and reducing their resilience.

Mexico notes that, with a population of 123 million growing at an average rate of 1.8 percent per annum, demand for food will be a key source of pressure on its fisheries and aquaculture sector, and mentions that it will be necessary to find new species to culture and new strategies for the sus-tainable use of already-established fisheries.

Where wild foods are concerned, population growth and urbanization are reported to be exerting increasing pressure on wild plant, fish and game populations in a number of countries, whether via the effects of increased demand or via habitat destruction. For example, Cameroon reports that population growth is creating more demand for forest products, including wild meat.

It notes that settlements are occupying land even in protected areas and that roads through parks are destroying habitats and disturbing wild species. Kiribati mentions that the most notable

7 the report cites Kålås et al. (2010).

driver affecting its wild food resources is popu-lation pressure, resulting either from increased urbanization or general high population growth.

It notes that a large proportion of the population is concentrated in urban centres and that this leads to overexploitation of some of the marine wild food species commonly used in these areas.

These species are reported to be easily accessible to the public, making them easy targets for unsus-tainable exploitation. Solomon Islands notes that in heavily populated urban and peri-urban areas marine species are being affected by effluent dis-charge, overexploitation and habitat destruction caused by land clearing and reclamation.