– Global urbanization will have significant
implications for biodiversity and ecosystems if current trends continue, with
knock-on effects for human health and development, according to a new
assessment by the United Nations Convention on Biological Diversity (CBD).
The assessment, which draws on contributions from more
than 123 scientists worldwide, states that over 60 percent of the land
projected to become urban by 2030 has yet to be built. This presents a major opportunity
to greatly improve global sustainability by promoting low-carbon,
resource-efficient urban development that can reduce adverse effects on
biodiversity and improve quality of life, it says.
The 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.
The world’s total urban area is expected to triple
between 2000 and 2030, with urban populations set to double to around 4.9
billion in the same period. This urban expansion will draw heavily on water and
other natural resources and will consume prime agricultural land.
"The way our cities are designed, the way people
live in them and the policy decisions of local authorities will define, to a
large extent, future global sustainability,” said Braulio Dias, Executive Secretary
of the CBD.
"The innovation lies not so much in developing
new infrastructural technologies and approaches but to work with what we
already have. The results often require fewer economic resources and are more sustainable,"
he added.
The report states that urban expansion is occurring
fast in areas close to biodiversity ‘hotspots’ and coastal zones. In rapidly
urbanizing regions, such as large and mid-size settlements in sub-Saharan Africa,
India and China, resources to implement sustainable urban planning are often
lacking. “More than half the global population already resides in cities. This
number is projected to increase, with 60 percent 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. “This report makes
a strong argument for greater attention to be paid by urban planners and
managers to the naturebased 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,” he added.
Cities are also increasingly recognized for their role
in supporting plant and animal species and diverse ecosystems. For example,
over 50 percent of Belgium’s floral species can be found in Brussels, while 65
percent of Poland’s bird species occur in Warsaw.
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 percent 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 bring positive effects for health and the
environment. “Cities need to learn how to better protect and enhance
biodiversity, because rich biodiversity can exist in cities and is extremely
critical to people’s health and well-being," said Professor Thomas
Elmqvist of the Stockholm Resilience Centre and Scientific Editor of the
report.
The Cities and Biodiversity Outlook 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, improving the bus transit system and
creating bicycle paths resulted in increased physical activity among residents,
and a reduction in greenhouse gases emissions. The report also provides detailed analyses of regional
urbanization trends and their impact on biodiversity and ecosystems.
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 urbanization, 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 urbanization may
decrease pressures on forests due to less use of fuelwood and charcoal.
- In China, urban areas are increasingly encroaching
on protected areas.
Africa:
- Africa is urbanizing 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 regarding 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 sixfold
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 urbanization level is 70-80
percent, 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 Cities and Biodiversity Outlook demonstrates how urban
areas can play a central role in achieving 20 key biodiversity goals (known as
the Aichi Biodiversity Targets) which were agreed upon in 2010 by parties to
the Convention on Biological Diversity.
For example, the restoration or ‘greening’ of
ex-industrial sites or brownfield land by city authorities can support efforts
to achieve Aichi Target 15, whereby 15 percent of degraded ecosystems are
restored by 2020.
Cities can also help prevent extinction of known
species (Aichi Target 12) through research and investment by zoos, aquaria and
museums, many of which are managed by city authorities.
The Cities and Biodiversity Outlook was produced by
the Secretariat of the CBD in partnership with the Stockholm Resilience Centre
(SRC) and Local Governments for Sustainability (ICLEI). The Secretariat of the
Convention on Biological Diversity operates under the United Nations
Environment Programme (UNEP). The full report can be downloaded atwww.cbd.int/subnational/partners-and-initiatives/cbo.
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