Global Warming Vs Climatic Change: A Case Study of Adilabad district, Telangana, India

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1 Global Warming Vs Climatic Change: A Case Study of Adilabad district, Telangana, India 1 Tammi Naidu, G., 2 Hema Malini B., and 3 Anuja Tigga, 1 Tammi Naidu, G., Post Doctoral Research Fellow, ICSSR, Department of Geography, Andhra University, Visakhapatnam Hema Malini B., Professor (Emeritus/UGC), Department of Geography, Andhra University, Visakhapatnam , 3 Anuja Tigga, Assistant Professor, Department of Geography, Andhra University, Visakhapatnam, Abstract Climate is a dynamic phenomenon which changes from time to time. In the past, climate variability was slow and gradual and it was due to natural causes. At present, the change in climate is rapid, irregular and dissimilar mostly due to human induced twin processes namely urbanization and industrialization. The present paper is an attempt to investigate whether global warming has any influence on the climate of Adilabad district in Telangana State. For that purpose, meteorological data on monthly temperature and rainfall were collected for 108 years ( ) and climatic data analysis has been carried out adopting Thornthwaite s (1955) water balance technique. Water balances of Adilabad were computed for normal year and for the years with the hypothesis of increase of temperatures by 2 o C, 4 o C, and 6 o C as predicted due to global warming. The study reveals that with the present day conditions of temperature and rainfall, Adilabad is experiencing Mega thermal type of climate (A ) based on Thermal regime and Semi Arid (D) climate based on Moisture regime. The hypothetical water balance models with 2 o C, 4 o C, and 6 o C monthly increase of temperature indicated that Adilabad will experience the same Mega thermal climate (A ) in future but not with the same intensity. Similarly, the existing Semi Arid (D) climate based on moisture regime may not be with same intensity. With the increased thermal potential the study area can support more vegetation growth but moisture status may not support. The Index of Moisture Adequacy (Ima), which indicates the suitability of crops and a declining trend in moisture adequacies. Key words: Global warming; water balance; Thermal and moisture regimes Introduction Climate of a region may be defined as the synthesis of weather elements prevailed over a long period of time at least 30 years (Ayoade,1983). The climate, in general is represented through the surface weather elements such as temperature, relative humidity, pressure, wind and precipitation (Bhaskara Rao et al., 2007). Climate is very dynamic phenomenon that fluctuates in all time scales: monthly, yearly, decadal, centennial and millennial (Hema Malini, 2002). The change in the weather parameters leads to fluctuations in climate of a region. Of late, of all the weather parameters temperature is on increase due to increase in the carbon dioxide and other green house gases in the atmosphere. Several research findings had also confirmed that the increase in global surface temperatures have been attributed to two important phenomena namely urbanization and Industrialization ( Rao,1983; Charlson,1993; Kumar et al., 2007; Riebeek, 2010). The human activities such as land use/land cover changes, deforestation, draining of wet lands tend to alter the albedo of the earth surface which in turn influence the variations in the microclimatic elements such as rainfall, temperature, humidities, etc (Landsberg,1984). Further, the process of urbanization creates concrete jungles which trap heat by multiple reflections, and the process of industrialization causes increase in greenhouse gases (Hema Malini, 1984). In addition, burning of fuel by vehicular traffic and domestic activities traps the heat at lower levels and raises the temperature near the ground (Rao et al.,2007; Katam et al.,2007). Study also revealed that increased emission from automobiles and industries contribute to increase diurnal variation in temperature (Tigga and Hema Malini, 2011). Analysis of the past 140 years of temperature data of the world revealed that the global temperatures are rising at a rapid rate. It was also found that the 20 th century was the warmest period in the last millennium with 1990s being the 1

2 warmest decade, and the 1998 the warmest year of the century (Dar,2007). The global climatic data shows that average surface temperatures have been increased over the past century by about 0.4 ºC to 0.8 ºC (Oliver and Hidore, 2002). NASA Earth Observatory based on IPCC s 2007 Fourth Assessment Report (US Environmental Protection Agency, 2010) indicated that the average surface temperature of the earth is likely to increase by 1.1 to 6.4 C by the end of the 21 st century, relative to , with best estimate of C. Riebeek (2010) also stated that based on a range of plausible emission scenarios, average surface temperatures could increase between 2 C and 6 C by the end of the 21 st century. It is assumed that global warming may effect that existing climatic patterns. Keeping this in view, an attempt is made in the present study to predict the future climatic patterns of Adilabad district.this study could be useful for district planners to foresee and comprehend the trends in the future climatic scenario so that prospective agricultural cropping and water resource management can be planned accordingly. Study Area Adilabad, the northern most district in Telangana State lies between the latitudes 18 40'N to 19 56'N and longitudes 77 46'E to 80 01'E (Fig.1). Adilabad district is bounded on the north by Yeovatmal and Chandrapur districts of Maharastra, on east by Chandrapur district of Maharashtra, on the south by Karimnagar and Nizamabad districts of Telangana and on the west by Nanded district of Maharastra. The Adilabad district is administratively divided into 52 Mandals and 1743 villages. The district covers an area of 16,115 Km². The total population of the district according to 2011 census is 2,741,239. Fig. 1: Location of Adilabad district in Telangana State and India Data and methodology Monthly temperature and rainfall data of Adilabad have been collected from the records of India Meteorological Department (IMD) and District Hand books for the period Average monthly water balance of Adilabad has been worked out using the book-keeping procedure of Thornthwaite and Mather (1955). Thornthwaite considered that air temperature is appropriate parameter to estimate Potential evapotranspiration. Precipitation (P) and Potential Evapotranspiration (PE) are the two fundamental elements of the water balance In Thorntwaite method precipitation being treated as income and potential evapotranspiration as expenditure and soil moisture as a reserve which may be drawn until it lasts. The comparison of monthly precipitation with PE enables to obtain numerical 2

3 values of water balance elements namely Water Surplus (WS), Water Deficit (WD), and Actual Evapotranspiration (AE). These parameters further facilitate to derive some important climatic indices namely index of aridity (Ia), index of humidity (Ih), index of moisture (Im). Based on the assumptions that the average surface temperatures could rise between 2 C and 6 C by the end of the 21 st century ( Riebeek,2010; US Environmental Protection Agency, 2010; Deem, 2006) and 2 C, 4 C, and 6 C temperatures were added to the existing average monthly temperatures ( ) and water balances were recomputed for hypothetical temperature situations and climatic types have been assessed. Distribution of water balance elements The average water balance elements of Adilabad were derived and presented in Table 1. The annual variations in water balance elements are graphically represented in Figure 2A and the predicted models are shown in figures- 2 B D. Table- 1: Normal water balance elements of Adilabad ( ) (All values are expressed in mm) Elements in Months Annual mm J F M A M J J A S O N D PE P AE WD WS Source: Computed by the authors(2010) Adilabad experiences 1658 mm of annual PE which is higher in most of the months except in November, December and January. Annual rainfall is only 998 mm. The analysis indicates that water need of the region is high throughout the year. Water need means total amount of water required for maximum evapotranspiration. Present analysis indicates that the atmospheric supply of water in the form of precipitation is much lower. Rainfall (P) exceeds the water need (PE) of the area only during July to September in which the region receives 85 percent of rainfall and in the remaining months rainfall is always less. The study area can meet the atmospheric demands only during monsoon months. As a result, water deficit occurs throughout the year except during southwest monsoon season i.e. from July to September. The excess rainfall during these months is enough to replenish the soil moisture storage. However, very little water surplus conditions do exist in the month of September normally. In the remaining months water surplus is always zero. Categorization of climates In the present context, based on the estimation of water balance conditions over a period, the type of climate under the influence of which a particular area can be assessed. Thornthwaite proposed two approaches namely thermal regime and moisture regime to categorize the climatic patterns of any region. He proposed Thermal regime classification based on thermal potential and moisture regime classification is based on moisture status of the region. Potential Evapotranspiration (PE) is an index of thermal efficiency which indicates not only growth of plants but also expresses growth in terms of water needed for the growth (Thornthwaite, 1948). The sum of the monthly values PE of a particular region is annual PE/TE (thermal potential) of that region. Based on the annual thermal potential values, Thornthwaite identified nine thermal regimes. Table 2 shows the scheme of thermal regimes. 3

4 Table- 2: Classification scheme based on Thermal Regime Annual Thermal Efficiency Climatic type Symbol (mm) Above 1140 Megathermal A' 997 to 1140 Mesothermal B' to 997 B' to 855 B' to 427 B' to 570 Microthermal C' to 427 C' to 285 Tundra D' Below 142 Frost E' Based on the above scheme Adilabad district comes under the influence of Megathermal (A') type of climate with annual thermal efficiency of more than 1140 mm. However, to find out the seasonal concentrations of thermal efficiency (thermal potential), Thornthwaite and Mather worked out summer concentration of thermal efficiency (SCTE) percentages (i.e., the ratio of the sum of the thermal efficiencies for the three highest summer months to the annual total). Based on SCTE % the thermal efficiencies are further classified into sub classes. Table 3 represents scheme of thermal regime sub classification. Table- 3: Classification scheme based on Summer Concentration of Thermal Efficiency SCTE (%) Climatic type Symbol Below 48.0 Megathermal a' 48.0 to 51.9 Mesothermal b' to 56.3 b' to 61.6 b' to 68.0 b' to 76.3 Microthermal c' to 88.0 c' 1 Above 88.0 Tundra d' Based on SCTE sub classification, it is noted that Adilabad experiences mega thermal (a' ' ) type of climate with SCTE per cent below 48. Based on annual as well as seasonal analysis it is found that Adilabad district is experiencing enormous thermal potential that can support luxuriant growth of vegetation if moisture is not a inhibiting factor. The moisture regime scheme of classification of Thornthwaite and Mather (1955) is based on moisture status of any region. The indices namely Index of aridity (Ia) and Index of humidity (Ih) which are derivatives of water deficit and water surplus respectively are the two indices to compute the main criteria of moisture regime namely moisture index (Im). Index of aridity is the percentage ratio between water deficit and Potential Evapotranspiration (Annual water deficit/ Annual PE x100) and Index of humidity is the percentage ratio between water surplus and Potential Evapotranspiration (Annual water surplus/ Annual PE x100). When Index of aridity is subtracted from Index of humidity the resultant value is moisture index (Im=Ih-Ia). Thornthwaite devised nine climatic moisture regimes based on the Index of moisture (Im). The classification of moisture regimes detailed in the Table 4. 4

5 Table- 4: General scheme of Thornthwaite (1955) climatic classification - moisture regime Climate type Symbol Moisture Index(Im) Vegetation Type Humid Climates(Im >0) Per humid A Above100 Rain Forest Humid B 4 80 to100 Forest Humid B 3 60 to 80 Forest Humid B 2 40 to 60 Forest Humid B 1 20 to 40 Forest Moist Sub humid C 2 0 to 20 Tall Grass Dry Climates (Im <0) Dry Sub humid C 1 Short Grass to 0 Semi-arid D to Steppe Arid E to 100 Desert Source : Thornthwaite (1955) Based on the above scheme, the climates namely Per humid, humid, Moist sub humid come under moist climates and climates namely dry sub humid, semi arid and arid come under dry climates. The moisture index indicates that a region is how much humid and how much dry. But, it is essential to know whether a region is continuously dry or wet throughout the year or continuously dry in one season and wet in other season. In moist climate, if there is dry season, it is important to know its intensity. Similarly in dry climates, if there is wet season, there is a need to know the intensity of wetness. In moist climates water deficiency may be large, moderate, little or non-existent. Same is true with water surplus in dry climates. To understand the seasonal variation of effective moisture Thornthwaite introduced sub classification in moisture regime. Table-5 provides scheme of sub classification of moisture regime climatic classification. Table -5: Sub categorization of Moisture regime climates based on seasonal variations Moist Climates (A,B andc 2 ) Variation of Water deficiency Symbol Aridity Index (%) Little or no water deficiency r Moderate summer water deficiency s Moderate winter water deficiency w Large summer water deficiency s Large winter water deficiency w Dry Climates (C 1, D and E) Humidity Index (%) Little or no water surplus d 0-10 Moderate winter surplus s Moderate summer surplus w Large winter water surplus s Large simmer water surplus w

6 Based on moisture regime classification it is found that Adilabad at present experiencing semi arid (D) type of climate and based on seasonal variation of aridity index, the district experiencing d type of semi arid climate with little water surplus condition. Thus, from the Thermal and moisture regime analyses, it was assessed that though annual as well as seasonal thermal efficiencies are adequate to support vigorous growth of vegetation, the drier semi arid nature of climate may not support that kind of thick vegetation. However, under semi arid conditions, Adilabad district supports only steppe type of vegetation. Moisture adequacy analysis To assess the impact of changing water balances on crop suitability, Index of Moisture Adequacy (Ima) has been computed. The Index of Moisture Adequacy (Ima) is the percentage ratio of Actual evapotranspiration to Potential evapotranspiration. It is particularly helpful in determining whether or not a given region is suitable for successful agricultural operations and if so for what type of crops (Subrahmanyam et al., 1963; Hema Malini, 1979, 1984). According to Subrahmnanyam and his associates (1963) low percentage values of index of moisture adequacy signifies the poor moisture availability and thereby low productivity. Table- 6: Scheme of crop suitability under different moisture adequacy conditions Ima percentage Above 80 Crop Suitability Efficiently suitable to paddy Suitable to paddy but yields are low; efficiently suitable to millets Suitable to millets Suitable only to drought resistant crops Below 20 Not suitable to crop agriculture The agro climatic analysis indicates that with the existing temperature conditions the water balance conditions of Adilabad district can support climatically only millet cultivation. Global warming Vs trends in climate An attempt has been made to predict the climatic change with the changing water balance conditions of Adilabad as a consequence of temperatures rise in the coming decades. Water balances were recomputed with the rise of 2 C, 4 C and 6 C temperatures (Fig.2). From the water balance analyses, it is found that the thermal efficiencies will be increased with the rise of temperatures. Annual water deficit conditions increases with temperature increase. Whereas, water surplus condition which normally exists during south west monsoon season declines with 2 C increase and completely disappears with further increase of temperatures. The climatic analysis for hypothetical water balance situations indicates that Adilabad district may experience same Mega thermal nature of climate (A ) even with the increase of temperatures but not with the same intensity. The study area may experience enormous thermal potential than the present and which can support luxuriant vegetative growth if rainfall is also abundant. Similarly, the Semi Arid (D) moisture regime climate, the present climate of the study area also same but the semi arid nature of the climate may shift towards more drier side and may shift even to Arid type of climate with the increase of temperature to more than 6 o C. Table -7 provides the consolidated changes that occur in water balance elements as well as climatic patterns of Adilabad district with warming of temperatures. 6

7 Fig. 2 :Normal water balance and hypothetical water balance models for temperature rise in Adilabad district Table- 7: Comparison of water balance parameters of , with 2 C, 4 C and 6 C temperature rise Water balance parameters (Normal) With Temperature rise of 2 C 4 C 6 C TE (mm) SCTE (%) Thermal regime type Megathermal (A'a) Megathermal (A'a) Megathermal (A'a) Megathermal (A'a) Ia ( %) Ih ( %) Im (%) Moisture regime type Semi-arid (Dd) Semi-arid (Dd) Semi-arid (Dd) Semi-arid (Dd) With the changing water balance conditions the moisture adequacies of Adilabad district also changes, thereby affecting the crop suitability. Table-8 shows the status of Index of moisture with temperature rise and crop suitability in Adilabad district. 7

8 Table-8: crop suitability status in different temperature situations in Adilabad district Agro- climatic elements With rise of Temperature 2 C 4 C 6 C Existing conditions I ma ( %) Crop suitability Millets Millets Millets Millets The study reveals that Index of moisture adequacy (Ima%) shows a declining trend with warming of temperatures by 2 o C, 4 o C, and 6 o C. Even with the rise of temperature the study area is suitable for growing millets. If moisture adequacy declines further even millet cultivation is not possible and the district should go for the cultivation of drought resistant crops. Conclusion The study reveals that Adilabad has a good thermal potential and experiencing Megathermal (A') climate. The water balance models constructed with an assumption of 2 C, 4 C and 6 C rise of temperature indicate that even with the rise of temperature Adilabad district will experience Megathermal (A') climate but not with the same intensity. The thermal potential will increase from 1658 mm up to 1808 mm, 2006 mm and 2129 mm with the rise of 2 C, 4 C and 6 C rise of temperatures respectively. The district will experience intensified thermal efficiencies during summer. Similarly, Adilabad which is under Semi-arid (D) type of moisture regime climate at present will experience same semi arid climate but with more dryness. With further increase in temperatures, the district may experience aridity in future. The agro climatic analysis indicates that the district is suitable for millet cultivation under normal conditions. However, change in water balance conditions with temperature increase may not affect the suitability status but the change may reflect in the quality and quantity of the yield. Further degradation of moisture adequacies may replace the millets by drought resistant crops. The study revealed that 2 C increase in monthly temperature is not a potential threat to the region. But temperature rise by 6 C may have some impact on biotic and a biotic elements. This type of analysis with scientific background and strong methodology are essential to understand the global warming scenario of any region to develop strategies in agricultural planning and water resource development from the point of view of food security. References Adilabad Hand Book of Statistics. (2009). Hand Book of Statistics, Adilabad District, Andhra Pradesh State Remote Sensing Application Centre, APSRAC, (2009). A Report on land use / land cover Mapping of Adilabad district, A.P. Under NR Census Program. Ayoade,J.O. (1983). Introduction to Climatology for the Tropics. New York : John Wiley & Sons. Pp Bhanu Kumar, Muni Krishna K.. & Ramalingeswara Rao S., (2007). Study of Global Warming Effect over Andhra Pradesh, Proc. of National Conf. on Global Temperature Rise: An Indian Effort towards Mitigation of CO 2 Emissions, organized by Dept. of Physical and Nuclear Chemistry and Chemical Oceanography Andhra University, Visakhapatnam, India, Sarma N. (editor), PP Bhaskara Rao, D.V., Srinivasulu D., and Ratna S.B., (2007). Climate Change with Special Reference to India: Present and Future Scenarios. Proc. of A.P., Academy of Sciences, Hyderabad Special Issue on Climate Change, Bahadur, Bir and Satyanarayana, B., (eds.) Vol. 11, No. 4., PP Charlson, T.C. Peterson, (1993). A new perspective on recent global warming: maximum and minimum temperature. Bull. Am. Met. Soc., 74, PP asymmetric trends of daily 8

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