Hyderabad: Global urbanisation 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 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 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,” 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.