International Journal of Scientific & Engineering Research, Volume 4, Issue 5, May-2013 956 ISSN 2229-5518 IJSER © 2013 http://www.ijser.org Evaluating temperature and precipitation variability over Gujarat, India from 1957-2007 Aparna Rathore * and Yogesh T Jasrai ABSTRACT The anthropogenic activities like industrialization, power production, deforestation, land use changes have all resulted into emissions of excess amounts of the greenhouse gases mainly carbon dioxide (CO2 ), nitrous oxide (N 2 O), methane (CH4 ), water vapour which have disturbed the normal energy balance of the Earth resulting into Enhanced greenhouse effect. This has caused the global mean temperature to rise by about 0.7°C and it is predicted that it will increase by 2-5°C by the year 2100. The rainfall has become more variable and the extreme events like cyclones, tsunamis, droughts, floods, heat and cold waves etc have also increased. All such climatic variability has a direct or indirect impact on the ecosystem involving plants, animals and humans. Climate change is likely to impact all the natural ecosystems as well as socio-economic systems. Climatic variability in terms of changes in temperature and precipitation pattern and their extremity pose a threat to the ecosystem and its services and therefore should be analysed in the past and present scenario to predict the future climate. In this paper past 50 years data of all IMD observatories in Gujarat state of India as obtained from IMD, Pune has been analyzed. The moving averages of maximum temperature during summer season and minimum temperature during winter season have been analysed and a significant increasing trend has been observed. The mean maximum temperature has been found to increase by 0.1°C and the mean maximum temperature has increased by 0.4°C over the past 50 years. Similarly the rainfall has also registered an increase in the past 50 years. Key words: Gujarat, climate, temperature, precipitation data INTRODUCTION Meteorological data compiled over the past century suggests that the earth is warming, but there are significant differences at regional level [13]. Over the last 100 years (1906-2005) the average temperature of the Earth’s surface has risen by 0.74±0.18°C [6,7,17] with two main periods of warming, between 1910 and 1945 and from 1976 onwards [21] and by 0.19°C per decade during 1979-1998 [10]. The rate of warming during the latter period has been approximately double that of the first and, thus, greater than at any other time during the last 1,000 years [21]. The IPCC predicts that, under business-as-usual scenarios mean temperatures worldwide will increase 1.4 to 5.8°C by 2100 as a result of growing GHG concentrations in the atmosphere [10,14]. The surface air temperature over India are going up at the rate of 0.4°C/hundred years particularly during the post monsoon and winter season [1]. Indian subcontinent has been predicted to experience an annual mean surface warming in the range between 3.5 and 5.5°C during 2080s [10]. • Aparna Rathore is currently pursuing PhD degree program in Botany at Department of Botany, Gujarat University, Ahmedabad, Gujarat, India. Email: rathoreaparna@ymail.com • Yogesh T Jasrai is currently Professor and Head, Department of Botany, Gujarat University, Ahmedabad, Gujarat, India. The monsoons are becoming quite uncertain with periods of droughts and floods. The frequency, intensity and duration of rainfall are also likely to change, with increased production risks, especially in semi-arid and arid rain-fed production areas [9,15]. There are already changes in the monsoon pattern with floods in Maharashtra, Gujarat and Rajasthan and drought in the North-East [2]. India may experience between 5 and 25% decline in winter rainfall leading to droughts in the dry summer months. On the other hand the average summer monsoon over Indian subcontinent is bound to increase by 10-15%. The date of onset of monsoon has also become variable [10,16]. The present paper reports changes in the climatic parameters (temperature and rainfall) in Gujarat over five decades of independent India. MATERIAL AND METHOD Study Area Gujarat is in the extreme West part of India (Figure-1). It has tropical climate, namely sub-humid, arid and semi-arid spread over different regions of the state. North Gujarat region comprising of Kutch, part of Banaskantha, Mehsana and North Western part of Saurashtra have arid climate while the South Gujarat have sub-humid climate and in the rest of the state, semi-arid climate. Temperature varies from 6 to 45°C. Annual rainfall varies from 250 mm in the North- West and to more than 1500 mm in South Gujarat. IJSER