Climate Change and Cities

The urban population is steadily increasing in absolute terms while the rural population is declining in all parts of the world. According to the United Nations Population Fund (2007), the world is experiencing the largest wave of urban growth in history. There were only two cities in the world with a population of more than a million in 1800. By 1950, there were already 75 cities of this size, and by the year 2000, there were already 380 cities with more than 1 million people, half of which were in Asia (Huq et al. 2007). In 2000, the average population of the 100 largest cities was 6.3 million. In 2008, more than half of the world's population lived in or around cities. By 2030, this number is projected to reach nearly 5 billion, with urban growth concentrated in Africa and Asia (Bicknell et al. 2009).

Every year, already existing cities increase in population by 67 million new urban residents. Much of this rapid urbanisation is taking place in developing countries (see Figure 5.7). By 2030, about 60% of the world's population will live in cities. This figure will remain until the middle of this century when it is projected that more than 65% of the world's population will be living in cities (IPCC 2014a-g). This rapid, unprecedented urban growth poses many challenges for cities, even without additional solutions to climate change. However, while the world's urban population is growing, cities, and the people living, there are becoming increasingly vulnerable to extreme weather events, including more frequent, longer, and more intense heatwaves, and inland floods due to heavy rainfall and coastal floods caused by sea-level rise.

  • - USA — Southern Africa ■ Brasil ----World
  • - India ------China ■ Vietnam


Proportion of population living in cities.

Source: World Bank.


Climate Change and Sustainable Development

Climate change is already happening, and cities increasingly need to plan and implement solutions to the various climate risks that can affect the health and well-being of the population, as well as the city's economy and infrastructure systems. 70% of cities are already facing the effects of climate change, and those effects are risky. For instance, more than 90% of all urban areas are on the coasts, making many cities around the world at risk of being flooded by sea-level rise and powerful storms. The financial effects of climate change can be as devastating as the physical and unexpected consequences of storms, floods, and droughts.

The chart below (Figure 5.8) provides an overview of how urbanised the world has become and what prospects for urbanisation are in the future. The figure shows that more and more people are living in cities.

As can be seen from Figure 5.8, the urban population exceeded the rural population around 1920. Such tendencies have persisted to this day. Moreover, the share of the urban population is projected to grow in the future, with 89.16% of the world's population living in cities by 2050 (see Figure 5.9), representing around 6.68 billion people (see Figure 5.10).

With more than half of the world's population living in cities, they need to address issues caused by climate change.

Cities are particularly vulnerable because they are "moving". Such urban infrastructures as bridges, metro systems, buildings and roads, a historic sense of the place, and the establishment of the population are very important elements of cities. Nevertheless, the strengths of such an area can become a

Proportion of population living in urban and rural areas, %

■ Rural population ■ Urban population


Proportion of population living in urban and rural areas.

Source: Our World in Data

Adaptation to Climate Change Impacts


Share of urban population (forecast until 2050), %

  • ----Sweden ----USA — India
  • China 1 Nigeria -----Bangladesh


Share of urban population (forecast until 2050).

Source: UN World Urbanization Prospects 2018.

Urban and rural population (forecast until 2050), billion


19001950196019701975 19801985 1990 1995 2000 2005 2010 2020 2025 2030 2035 2040 2045 2050

Urban areas Rural areas


Urban and rural population (forecast until 2050).

Source: UN World Urbanization Prospects 2018.)

commitment if the local ecosystems on which they rely are unable to adapt to climate change. Climate change poses a serious threat to urban infrastructure, quality of life, and all existing urban systems. Not only poor but also rich countries will be increasingly affected by abnormal climate phenomena and climate change tendencies (World Bank 2010).


Climate Change and Sustainable Development

Urban areas are severely affected by climate change and major factors of greenhouse gas emissions. Cities play a key role in adapting to climate change.

Urban areas emit up to 70% of the world's anthropogenic greenhouse gases into the atmosphere, with fossil fuel combustion being the main source. In order to achieve the 2015 Paris Agreement on climate change under the objective of maintaining the temperature significantly lower than 2°C compared with pre-industrial period, it is necessary to keep the "carbon budget" and emit into the atmosphere no more than about 800 gigatons of CO2. An important step in analysing urban greenhouse gas emissions is the development and use of standardised methodologies. Such methodologies allow the comparison of the cities and provide information on the cities' contribution to national emissions. Officials in the cities are increasingly taking action by setting city-level emission reduction targets or using other measures, such as expanding the use of renewable energy technologies.

Leaders of the cities are in the right position to address climate challenges for two main reasons: first, cities are major energy consumers, consuming two-thirds of the world's energy while generating more than 70% of greenhouse gases. Second, city mayors in many countries are directly accountable to their constituents for their decisions that affect global change and daily life.

Table 5.2 summarises the results of technical analysis report conducted by the Urban Climate Change Research Network (UCCRN) of 2018.

The technical analysis carried out by UCCRN includes three main components:

  • 1. the analysis of climate damage data from six major cities on a global scale;
  • 2. a case study that contextualises the six key vulnerabilities and how cities respond to them; and
  • 3. the geographic information system (GIS) database that assesses the layers of maps that can be used to assess these six hazards in different cities around the world.

This technical report includes the results of a global data analysis, global city maps that are expected to be exposed to vulnerabilities, and case studies based on research derived from tangible urban experiences.

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