| Issue 20 Vol I, July 31, 2006 | Archive |
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Heat Islands and Global Warming FOR the readers let me first explain the meaning of the scientific term “Heat Island”. We all know that the islands are masses of land sprouting out of bodies of water such as oceans, seas, bays, rivers and lakes. Similarly the heat islands are patches of areas exhibiting consistently higher ground and atmospheric temperatures compared to their surroundings areas. The simplest example can be that of a bonfire in the midst of a forested area. The ground, where the fire is lit and the air immediately above it exhibits a higher temperature compared to the surrounding forested area. We can technically call this localized area of the bonfire as the area of a heat island. Heat islands are an indicator of global warming. Their increasing numbers and expanding sizes are indicating that the World is warming. This situation if not corrected, in a timely fashion, can lead to permanent ecological changes, which will spell disaster for growing crops. On a larger scale let us take the example of the city of Pittsburgh in Pennsylvania State of the United States. Including its suburbia, this is an industrial metropolis of more than two million people. Until recently, Pittsburgh was nicknamed as the Steel City of America. Its furnaces and steel plants were churning out millions of tons of billets, rods and sheets of steel per year, not only for the domestic needs of the United States but also for export to markets all around the globe. In addition to the heat generated by its mills and factories, the city is host to a million and half automobiles. All the homes are centrally heated. But if you go only a mile outside the municipal limits of its suburbia, there are thick growths of lush green forests of pines, birches, maples, willows, cherries and several other cold weather trees. The forested area around Pittsburgh exhibits consistently lower ground temperatures which are closer to the earth’s mean temperatures in the area. These temperatures are approximately five degrees lower compared to the city and its suburbs. We can say that the Pittsburgh Metropolitan Area is a heat island alien to its much larger natural surroundings. Such heat islands exist all over the United States in the metropolitan areas. All major cities, because of their thicker densities of populations, thinner covers of trees, millions of automobiles and centrally heated houses, offices and business establishments have created localized heat islands. The United States spread over 3.6 million square miles and hosting a population exceeding 280 million has in excess of 1000 heat islands located mostly on the affluent Eastern and the Western Seaboards and the rust belt comprising of Great Lakes Rim States. Canada spread over as much area as the Continental United States, has less than 30 million population and less than 100 heat islands. Australia fares even better than Canada due to lesser population and fewer metro-cities. New Zealand has been more effective than even Australia in maintaining its green cover and in limiting the size of its urban areas. New Zealand has also succeeded in maintaining well defined green belts within the cities. Let us discuss as to how the existence of a heat island can be mapped. The old fashioned way is to record the maximum and minimum temperatures at various points in the urban area under study. The same should be done in the suburbia as well as the natural forested lands located around the urban and the suburban areas. Contours of identical temperatures or isothermal lines can be drawn for the urban area, the surrounding suburbs and the natural forested areas. The areas of higher temperatures can appropriately be clubbed as heat islands. Now a day the same can be done by satellite mapping, which is the preferred mode throughout the World these days. The development of heat islands, Western Europe fares worse than the United States. This is due to centuries old over population of European Continent, ever increasing numbers of automobiles and heating of homes, offices and businesses during the cold weather. Perhaps the worst farers in the World are India and China. Though our houses are not heated, but the massive sizes of populations and the emissions from automobile explosion are enough for the creation of thousands of heat islands in both India and China. The United States, Canada and Europe, because of the maintenance of massive covers of forests in their countryside have faired much better than countries like India and Brazil. Brazil has been responsible for the wanton destruction of its once magnificent rain-forest. India has been mercilessly destroying its forest cover for more than a century, primarily to grow food and other agricultural necessities for its population. Initially the forests in the plains were cut to make room for the cultivation of staple foods and cash crops, but now even in the eco-friendly Himalayan belt, the forest cover is vanishing at an alarming rate. The result is increase in temperatures especially during the summer and the formation of thousands of heat islands throughout the country. India’s case is the worst. We support 3.5 times the population of the United States in an area which is one third of that country’s. Our heat islands, perhaps never mapped are much larger and much more numerous than those in the United States. Our awareness about this disastrous condition is at best poor. In the Indo-Gangetic heartlands of this country, perhaps the largest heat island is formed around the metropolis of Calcutta. The second largest heat island exists in the Delhi-Gurgaon-Faridabad-Noida-Ghaziabad metropolitan area. In addition there is evidence of rubber-necking of heat islands from Delhi to Lucknow and Kanpur to the East, to Agra-Mathura area in the South and to Lahore via Panipat, Karnal, Ambala, Rajpura, Sarhind, Gobindgarh, Khanna, Doraha, Ludhiana, Phillaur, Goraya, Phagwara, Jalandhar and Amritsar in the West. Both Metropolitan Delhi (guesstimated current population 14 million) and Lahore (guesstimated current population 9 million including Gujjranwala) are the largest heat islands in the North-West of the Indian Sub-Continent. In the absence of a well meaning tree cover in the entire length of the Indo-Gangetic belt, the conditions even in the rural areas are not much better than those in the urban sprawl. At the end of each cropping season, after harvesting is over, even the agricultural fields also lose their green cover and in some cases become parts of heat islands. We can not compare the surroundings of Pittsburgh with the areas around Delhi and Lahore. Where as Metropolitan Pittsburgh is surrounded by thick green and healthy forest, both Delhi and Lahore are surrounded by bald scorched earth. The unusual amount of dust in the air all over the plains of India is partly due to erratic rainfall and partly due to non-existence of a decent cover of forest. In a nutshell, we have much worse ecological problem in India than in the United States. The government in the United States both at the federal level and state level is aware of the existence of heat islands and they are contemplating to find ways and means to alleviate it. We in India, I think, are totally oblivious to this menace. Our ground temperatures are rising menacingly year after year. This year’s lower yield of wheat in Punjab and other northern wheat growing states is due to early warming, which started in February rather than in the usual month of March. I think there is no concerted move on the part of the authorities to tackle this problem of excessive warming. The idea of writing this article is to generate a healthy intellectual debate in India to create awareness in the population about the existence of this problem. The government should take a note of the enormity of this problem and stir into some kind of remedial action. The phenomena of the formation of heat islands have already resulted in longer and warmer summers even in the hill areas of India. Delhi has experienced worst rise in summer temperatures in recent history. Five decades ago, if the day time temperature hit 40 degrees Celsius even in July, it raised alarm bells. Now even in April, the mercury usually hits 40+. There are days in May, June and July, when the day time temperatures exceed 45 degrees. Other Indian cities are also heating up similarly. The hitherto unprecedented, but now ever increasing, summer time power crisis in Punjab and the northern power grid is partly caused by the rapidly rising demand for air-conditioning and partly by the electric demand of the ever increasing number of tubewells. Industrial demand, other than for air-conditioning, is in fact declining in all major industrial cities. All these developments are ominously linked to heat islands and global warming. The glaciers in Jammu and Kashmir, Himachal Pradesh and Uttaranchal are melting at an alarming rate. Consequently the level of the Arabian Sea and the Bay of Bengal is rising. Perhaps the island nation of Maldives and India’s own archipelagos of Andaman and Nicobar and Lakshdweep will lose some of their islands to the rising level of the seas over the coming few decades. One temporary solution lies in consuming all the run off from melting snows for irrigation and rural and urban household consumption. This can be done by impounding the rain water run off and by harvesting water from melting snows by building a number of low height dams on the rivers. Pakistan is doing it in the Province of Sindh. We should do the same in Punjab, U.P. and Bihar. The emergence of heat islands in India is a serious ecological problem, which should not be brushed under the rug. [HARJAP SINGH AUJLA is a water resources engineer with twenty six years of service in the United States.] |
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