Increasing urbanization over the next decades presents not only unprecedented challenges for humanity, but also opportunities to curb climate change, reduce water scarcity and improve food security, according to the world's first global assessment on the relationship between urbanization and biodiversity loss, released last week in New York.
The assessment, entitled Cities and Biodiversity Outlook (CBO), argues that cities should facilitate for a rich biodiversity and take stewardship of crucial ecosystem services rather than being sources of large ecological footprints. The volume of research is produced by the Stockholm Resilience Centre (SRC) together with the Secretariat of the Convention on Biological Diversity (CBD), in partnership with UN-Habitat and ICLEI - Local Governments for Sustainability.
The detailed scientific foundation of the CBO, Urbanization, Biodiversity and Ecosystem services: Challenges and Opportunities – A Global Assessment, , has involved more than 200 scientists worldwide. It states that over 60 percent of the land projected to become urban by 2030 has yet to be built. It further states that if current trends continue, 70 percent of the global urban population will be urban by 2050.
The report says 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.
From emitters to carbon sinks
While production and consumption activities heavily concentrated in cities have contributed to some 80 percent of all greenhouse gas emissions, the report suggests that innovative solutions to combating climate change will also come from cities.
Preservation of larger outlying green areas, green corridors that connect larger green patches, green roofs and "brownfields", or land previously used for industrial purposes or certain commercial uses, can also be used as carbon sinks rather than emission sources.
The Japanese district of Yokohama, for instance, which emitted almost 20 million tons of CO2 in 2007, has recognized the importance of biodiversity in stabilizing the local climate. Revenues from a new tax system have since been used to conserve green areas, and roof tops and walls were fitted with greenery. Yokohama is now aiming to reduce per capita carbon emissions by at least 60 percent by 2050. What is important, according to the assessment, is to develop and incorporate already existing green spaces into the functional infrastructure of a city.
Professor Thomas Elmqvist, scientific editor of the assessment, commented:
"The innovation lies not so much in developing new infrastructural technologies but to work with what we already have. The results are often far cheaper and more sustainable as well."
Dr. Braulio Ferreira de Souza Dias, Executive Secretary of the CBD, added that “the sphere of influence of city leaders goes well beyond urban habitats. The decisions taken by local authorities affect ecosystems near and elsewhere, with important feedback effects. By taking the steps to conserve and sustainably use biodiversity, local authorities can ensure that biodiversity will continue to provide cities and their inhabitants with much needed services including freshwater, clean air, food security and protection and resilience against extreme weather, floods and other environmental risks.”
The report reflects the increasing drive towards the development of more blue-green infrastructure to address a growing number of water and wastewater resource issues worldwide, including the UK. The use of Sustainable Urban Drainage Systems (SUDS) to drain surface water as a more sustainable approach to traditional solutions looks set to play a key role in the move towards more sustainable cities.
To read more about the CBO assessment visit www.cbobook.org