The Poineer: The United Nations’ (UN) International Day for the Preservation of the Ozone Layer is celebrated on September 16 every year. This event commemorates the date of the signing of the Montreal protocol on substances that deplete the ozone layer in 1987. States were invited to devote the day to promote activities in accordance with the objectives of the protocol and its amendments.
This year’s theme of the international day is “HCFC phase-out: A unique opportunity”. HCFCs (hydro chlorofluorocarbons) are both ozone-depleting substances and powerful greenhouse gases. Attention is focused initially on chemicals with higher ozone depletion potentials, including CFCs and halons. The phase-out schedule for HCFCs was more relaxed due to their lower ozone depletion potentials and because they have also been used as transitional substitutes for CFCs (Chlorofluorocarbons). The HCFC phase-out schedule was introduced in 1992 for developed and developing countries, the latter with a freeze in 2015, and final phase-out by 2030 in developed countries and 2040 in developing countries. In 2007, parties to the Montreal protocol decided to accelerate the HCFC phase-out schedule for both developed and developing countries.
HCFCs are potent ozone depletors. One of the main reasons for the widespread concern about depletion of the ozone layer is the anticipated increase in the amounts of ultraviolet radiation received at the surface of the earth and the effect of this on global climate. Global climate change presents one of the foremost threats —economically, socially and environmentally — of the new century. Increases in the concentration of greenhouse gases in the atmosphere are expected to result in substantially higher temperatures, more frequent intense storms, rising sea levels, and changes in water flows and quality. The human activities are contributing to these changes, largely by releasing carbon dioxide into the atmosphere through burning fossil fuels to generate electricity, manufacture goods and energy used in homes.
Over the last 20 years, urban centres have experienced impressive growth. Today half of the world”s total population lives in urban settlements. Cities are lifelines of society and engines for economic growth. They are centres of technology and innovation and they serve as living evidence of our cultural heritage. However, rapid urban growth poses many challenges to city authorities and if not well managed, cities can also become generators of new vulnerabilities, which can add risk to disasters.
Developing countries in particular are undergoing rapid changes from rural to urban-based economies as they are transformed by their urbanising populations. The urban population in India has increased from about 26 million in 1901 to 110 million in 1971 and 217 million in 1991. This further increased to 286 million in 2001 and the total urban population in the country as per Census 2011 is more than 377 million constituting 31.16 per cent of the total population. The country is already experiencing changes in climate and the impacts of climate change, including water stress, heat waves and drought, severe storms and flooding and associated negative consequences on health and livelihoods. The impacts of urbanisation and climate change bring opportunities to rethink how we manage future growth of our cities.
Human emissions of carbon dioxide and other greenhouse gases lead the earth”s atmosphere to capture and retain more heat from the sun than is lost by radiation into space. The global temperature record shows an average warming of about 1.1 0F over the past century. Global warming is now one of the most important environmental issues. The main greenhouse gas is carbon dioxide, and its concentration in the atmosphere has increased from the pre-industrial value of about 280 parts per million (ppm) to some 382 ppm in 2008. The concentration of carbon dioxide has reached to 394.49 ppm in 2012. It will take centuries to reduce this concentration, and possibly more than a century even to stop it increasing. Meanwhile, this increase in greenhouse gases has already had impacts on the climate, and on natural ecosystems and human societies.
Our health, agriculture, water resources, forests, wildlife and coastal areas are vulnerable to global warming and the climate changes. Climate change is likely to have wide ranging adverse impacts on human settlement with significant loss of life. A few degree of warming increases the chances of more frequent and severe heat waves, which can cause more heat-related death and illness.
Cities contribute much to the causes of climate change in terms of green house gas (GHG) emissions, land-use change and deforestation. The role of city planning is to manage the spatial organisation of cities for efficient allocation of urban infrastructure and land use. Urban planning can improve environmental quality in the long run by strategic location of polluting sources and encouraging a city structure that would minimise emissions.
Climate change is a serious challenge for city planning around the world. Cities are the key contributors to global warming. Cities which implement sustainable energy and climate action plans reduce their vulnerability to climate change. There is a need to study the nature of these changes and their ramification for sustainable human settlement. It has become apparent that the time is at hand to begin planning and redesigning urban areas with much more attention to climatic considerations.
The development of new towns or development of existing urban places requires careful study of climatic condition of the region. The selection of sites for new industrial plants should include meteorological studies. A careful evaluation of the meteorological, topographic and engineering factors can avoid hazardous pollution in the atmosphere.
It is imperative to implement Town planning Act to reduce the impacts of climate change. Climate change impact on land-use development is an important issue in today”s context. Land-use development involves decisions concerning building density, spacing, height and collective massing.
All settlements should provide sufficient green areas. The use of green areas is a major planning technique by which town planners can prevent or reduce adverse effects of climate. Green areas should be dispersed throughout an urban area and legally protected. Therefore, many cities in the developed world are planning to transform themselves into green metropolis over the next 10-20 years. The Government of India has prepared a National Action Plan for Climate Change. In order to address issues relating to mitigation and adaptation in human settlements, a National Mission on Sustainable Habitat is proposed to be launched. The mitigation measures would primarily include energy efficiency in buildings, improved urban land use planning and shift to public transport, and management of water, waste water and solid waste. Apart from this, the mission would also facilitate adaptation to vulnerabilities arising out of climate change like adverse impacts on water resources, increased frequencies of extreme weather like droughts, floods, cyclones, storm water surge, rise in sea levels and heat waves.
Urban planning is increasingly important in managing climate change because well-planned cities are more adaptive to climate change and resilient to its negative impacts than unplanned or poorly managed cities. Well planned cities will be able to protect them from disasters and climate change impacts now and in the future. Having a well-planned city therefore not only improves the standard of living but decreases damage done on the environment. Finally, a sustainable city with environment friendly buildings can maintain good environmental quality, which will reduce ozone depletion and global warming.
(Dr Praharaj teaches in the Department of Architecture, College of Engineering and Technology, Bhubaneswar)
