One of the most important environmental concerns the world faces today is of depletion of the ozone layer in the stratosphere. The concern is because of the fact that the ozone layer plays a protective role, screening the earth from harmful ultraviolet radiations.
The depletion of the ozone layer has been a cause of concern for global community as it affects human health and natural ecosystems. This realisation has prompted development of control measures to save the ozone layer.
The United Nations General Assembly in December 1994 adopted a resolution proclaiming September 16 as the International Day for the Preservation of the Ozone layer. The theme for the day this year is ‘A healthy atmosphere, the future we want’.
As the world’s urban population increases, urban areas encounter new phenomena and problems. Uncontrolled uses of resources, greenhouse effect, ozone depletion, etc., have been caused by urbanisation and industrialisation. Urban centres have concentrated industries, construction, transportation and households. land-use changes induced by urban growth may lead to deforestation and reductions in the uptake of CO2 by vegetation. landfill sites taking up urban wastes also generate methane. Cement, as a construction material of primary importance to development of urban infrastructure as well as of commercial and residential buildings, also has a large carbon footprint due to an energy-intensive manufacturing process and high energy cost for transporting this dense material.
lastly, many activities like agriculture, livestock production, mining and timber collection increase GHG emissions as direct emitters or reduce the uptake of these gases by vegetation.
Most global and regional environmental problems originate in cities. Cities concentrate increasing numbers of people and human activities; thus, they import increasing amounts of natural resources and export vast quantities of emissions and waste. Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are GHGs that are produced solely by human activities. CFCs were widely used as refrigerants before it was discovered that their presence in the atmosphere caused the depletion of the ozone layer. The main human sources of GHGs contributing to global warming are the dramatic rise in energy use, land-use changes and emissions from industrial activities.
Reducing the contribution of cities to climate change, or mitigation, requires an adequate understanding of the drivers of urban GHG emissions, while effective adaptation must be based on a good understanding of what makes cities and their constituent socioeconomic groups either vulnerable or resilient to climate change impacts. Reducing GHG emissions is, therefore, one of the key policy challenges that cities face. The size and density of population are key determinants of cities’ GHG emissions. So, it is important to have a framework for understanding the levels and drivers of emissions by different demographic and economic sectors, buildings and infrastructures within, or serving urban areas.
Motor vehicles are the primary cause of pollution in cities. Producing the energy required to run modern urban systems often involves burning fossil fuels, which releases such greenhouse gases as carbon monoxide, carbon dioxide and nitrogen oxides. The increasing demand for energy to run air conditioning and electrical appliances is also contributing to pollution. These emissions lead to global warming, which can cause destruction of the ozone layer and climate change.
Transport policy, planning and land use policy are fundamentally linked. The pattern and density of urban development has a major influence on travel patterns. Sustainable city planning should aim at achieving social and environmental equity while improving the lives of the people. For that to happen, we need to have a sustainable city form as well as provision and proper management of the services. Thus, in order for a city or urban area to be sustainable it needs to produce and manage basic services like water, waste, energy and transportation in a way that it conforms to the principles of sustainable development. In other words, the city should be able to produce and distribute the services in an economic, environment-friendly and equitable way.
While planning for sustainable development of the towns, we should also take into account the factor of climate change. Planning looks at the needs of people and the environment whilst respecting limits to development. Urban planning must recognise regional limits to development in order to maintain natural habitats and biodiversity, which is so important to our continued existence. Broad landscape conservation is necessary to maintain ecosystem function and biodiversity, but there is also a great opportunity for sensitive redevelopment of many previously-developed areas. Urban design facilitates individual building lots to maximise winter sun penetration, minimise excessive summer heat gain and the design and construction of dwellings that are designed with passive solar design principles.
The rapid demographic growth in and around Indian cities is changing the physical dimensions of its cities, that is, the size, shape, density, land uses, spatial structure and building types. Increased urban development puts intense pressure on existing urban infrastructure to support a good quality of life. Rapid urban growth often manifests itself as overcrowded and very high-density urban forms, claimed to contribute to crime, physical and mental illness and poor living conditions. Such urban forms are, therefore, generally considered to be socially, environmentally and economically unsustainable.
Sustainable urban development is an integral component of the universal aim of “Sustainable Development”. If properly designed, constructed and operated, a sustainable city and sustainable building will require less money and fewer resources to operate, and will be healthier for its occupants. Buildings are “sustainable” when they are designed, built and operated with low environmental, social, and economic impacts while enhancing the health, welfare and quality of life of the people.
For sustainable urban development, a number of urban programmes have been initiated by Government of India. Recent urban initiatives of the Government of India include Jawaharlal Nehru National Urban Renewal Mission (JNNURM), e-Governance in Municipalities, National Urban Sanitation Policy, Citywide Slum Upgradation Programme, setting up of Centres of Excellence in Urban Development, Sustainable Habitat Mission - Green Building, public transportation and solid waste management.
Recognising the importance of urbanisation and its vulnerability from climate change, the National Action Plan on Climate Change had proposed setting up of a National Sustainable Habitat Mission. The mission looks at developing standardised eco-building norms to promote energy efficiency, improved urban planning by integrating land use and transportation plans and focus on shift towards public transport to facilitate growth of cities, promoting sustainable waste management focusing on reduce-recycle-reuse and waste-to-energy options.
India became a party to the Vienna Convention for the Protection of the Ozone layer and the Montreal Protocol on Substances that Deplete the Ozone layer and has ratified all the amendments to the Montreal Protocol. Ozone Depleting Substances (Regulation and Control) Rules, 2000, provide a comprehensive set of regulations to control and monitor production and use of ozone depleting substances (ODS) in India.
Besides, there are a number of practical measures which can be taken at individual level to protect the nature earth. Everyone should be responsible for the use and abuse of certain products that have a negative effect on nature. There are many simple ways in which we can save our ozone layer. We should use alternative means of transport: buses, bicycles, or simply walk.
To protect the ozone layer, we must prevent the release of ozone-depleting substances to the atmosphere. Whenever possible, we must also replace them with safer alternatives. Before demanding implementation of policies, let’s begin ourselves doing something to protect the ozone layer and save our environment.
(Dr Mayarani Praharaj works at the Department of Architecture, College of Engineering and Technology, Bhubaneswar)