UN report warns of effects of urban expansion on biodiversity

A new assessment by the United Nations Convention on Biological Diversity (CBD) warns that if the current trend of global urbanisation continues, it will have significant implications for biodiversity and ecosystems along with knock-on effects on human health and development.

The assessment report states that urban expansion is occurring fast in areas close to biodiversity hot spots and coastal zones. In rapidly urbanising regions, such as large and mid-size settlements in sub-Saharan Africa, India and China, resources to implement sustainable urban planning are often lacking.

Key highlights of the report   ASIA • The region will be home to almost half the world’s increase in urban land over the next 20 years. The most extensive changes will occur in India and China •India’s growing urban clusters (such as the Mumbai-Delhi industrial corridor) are likely to transform entire regions with significant impacts on habitat and biodiversity • Loss of agricultural land to urbanisation, combined with insufficient planning for food supply lines, places a severe constraint on future food security for India’s growing population • Lifestyle changes in India due to urbanisation may decrease pressure on forests due to less use of fuelwood and charcoal • In China, urban areas are increasingly encroaching on protected areas AFRICA • Africa is urbanising faster than any other continent, and most population growth will occur in cities of less than 1 million people. These cities often have weak governance structures, high levels of poverty and low scientific capacity for managing biodiversity • Low levels of formal employment in cities places high dependency on the provision of ecosystem services (e.g. water and food production) from areas either within or close to city limits. LATIN AMERICA AND THE CARIBBEAN • The number of cities in the region has grown six-fold in the past 50 years • Urban sprawl caused by housing for low-income residents often occurs in important areas for biodiversity and ecosystem services, such as wetland or floodplains. These are mistakenly considered to be of marginal value by planners EUROPE AND NORTH AMERICA • In Europe, the current urbanisation level is 70-80 per cent, and urban growth in recent decades has mostly been in the form of land expansion rather than population growth • Many European and North American cities have exhibited trends of shrinking and/or shifting patterns of population in central parts of the cities, coupled with sprawl in outer suburbs and exurban areas

The report, Cities and Biodiversity Outlook, is the world’s first global analysis of how projected patterns of urban land expansion will impact biodiversity and crucial ecosystems. It was released in Hyderabad during CoP 11 on October 15. It has been put together by the secretariat of CBD in partnership with the Stockholm Resilience Centre and Local Governments for Sustainability.

Window of opportunity
The report is an assessment by more than 123 scientists all over the world, and states that 60 per cent of the land projected to become urban by 2030 is yet to be built. So there is still a major opportunity to greatly improve global sustainability by promoting low-carbon, resource-efficient urban development that can reduce the adverse effects on biodiversity and improve quality of life.

According to the report, the world’s total urban area is expected to triple between 2000 and 2030, with urban population set to double to around 4.9 billion in these three decades. This urban expansion will draw heavily on water and other natural resources and will consume prime agricultural land.

Releasing the report, CBD executive secretary Braulio Ferreira de Souza Dias said, “the way our cities are designed, the way people live in them and the policy decisions of land authorities will define, to a large extent, future global sustainability.” He added that the innovation lies not so much in developing new infrastructure technologies and approaches but to work with what we already have. The results often require fewer economic resources and are more sustainable.

“More than half the global population already resides in cities. This number is projected to increase, with 60 per cent of the population living in urban areas by 2030,” said Achim Steiner, UN under-secretary general and executive director of the United Nations Environment Programme. He added that the report makes a strong argument for greater attention to be paid by urban planners and managers to the nature-based assets within city boundaries. Sustainable urban development that supports valuable ecosystems presents a major opportunity for improving lives and livelihoods, and accelerating the transition to an inclusive green economy.

Cities are also increasingly recognised for their role in supporting plant and animal species and diverse ecosystems. For example, over 50 per cent of Belgium’s floral species can be found in Brussels, while 65 per cent of Poland’s bird species occur in Warsaw.

Urban lungs
Urban green spaces perform important ecosystem services, such as filtering dust, absorbing carbon dioxide from the air and improving air quality. Data from the United Kingdom shows that a 10 per cent increase in tree canopy cover in cities may result in a 3-4°C decrease in ambient temperature, thus reducing energy used in air conditioning.

Urban biodiversity also delivers important health benefits. Studies have shown that proximity to trees can reduce the prevalence of childhood asthma and allergies. Sustainable urban planning, which addresses biodiversity issues along with other priorities such as poverty alleviation, employment and housing, can benefit health and the environment.

The report highlights a wide range of successful initiatives by cities, local authorities and sub-national governments in both developed and developing countries. In Bogotá, Colombia, measures such as closing roads on weekends to motorized vehicles, improving the bus transit system and creating bicycle paths resulted in increased physical activity among residents, and a reduction in greenhouse gas emissions. The report also provides detailed analyses of regional urbanisation trends and their impact on biodiversity and ecosystems.
 

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