Analyzing changes of temperature over Bangladesh due to global warming using historic data Dr. A.K.M. Saiful Islam Associate Professor Bangladesh university of engineering and technology Email: akmsaifulislam@iwfm.buet.ac.bd

Introduction Intergovernmental Panel on Climate Change (IPCC) has reported in their fourth assessment report that global surface temperature increased 0.74 ± 0.18 °C during the 100 years ending in 2005. In this context, long term changes of near surface air temperature over Bangladesh have been studied using the available historic data collected by the Bangladesh Meteorological Department (BMD).

Data Maximum and minimum daily temperature data of last sixty years (1948-2007) collected from 34 stations of BMD located all over the Bangladesh have been used in this study. Trend analysis has been conducted on monthly data for all the stations

Study Area

Trend Analysis Increase 0.63 0C on 100 years scale

Trends of Minimum Temp Increase 1.37 0C on 100 years scale

Trends of Temperature For 34 ground measuring Stations of BMD ID Latitude Longitude Altitude Max. Temp. (0C per yr.) Min. Temp. (0C per yr.) 11704 Barisal 22.72 90.37 2.1 m 0.0077 -0.0163 11706 Bhola 22.68 90.65 4.3 m 0.0170 0.0206 10408 Bogra 24.85 89.37 17.9 m 0.0117 0.0404 11316 Chandpur 23.23 90.7 4.9 m 0.0163 0.0161 11921 Chittagong 22.35 91.82 33.2 m 0.0224 0.009 41926 Chuadanga 23.65 88.82 11.6 m -0.0038 0.0217 11313 Comilla 23.43 91.18 9 m 0.0049 -0.0009 11927 Cox's Bazar 21.45 91.97 0.0295 0.022 11111 Dhaka 23.78 90.38 6.5 m 0.0119 0.0225 10120 Dinajpur 25.65 88.68 37.6 m -0.0213 0.0151 11505 Faridpur 23.93 89.85 8.1 m 0.0275   -- 11805 Feni 23.03 91.42 6.4 m 0.0174 0.0331 11814 Hatiya 22.45 91.1 2.4 m 0.0261 -0.0202 10910 Ishardi 24.15 89.03 12.9 m 0.0032 0.0037 11407 Jessore 23.2 89.33 6 m 0.0147 0.0113 12110 Khepupara 21.98 90.23 1.8 m 0.0266 11604 Khulna 22.78 89.53 -0.0053 11925 Kutubdia 21.82 91.85 2.7 m 0.0416 0.0248 11513 Madaripur 23.17 90.18 7 m 0.0047    -- 11809 Maijdicourt 22.87 0.0193 0.0204 41958 Mongla 22.47 89.6 0.0430 0.0104 10609 Mymensing 24.73 90.42 18 m -0.0086 0.0086 12103 Patuakhali 22.33 90.33 1.5 m 0.0328 0.026 10320 Rajshahi 24.37 88.7 19.5 m 0.0110 0.0027 12007 Rangamati 22.63 92.15 68.9 m -0.0039 -0.0178 10208 Rangpur 25.73 89.27 32.6 m -0.0259 0.0281 11916 Sandwip 22.48 91.43 2 m 0.0074 -0.0182 11610 Satkhira 89.08 4 m 0.0065 0.0107 41858 Sayedpur 25.75 88.92 39.6 m 11912 Sitakunda 91.7 7.3 m 0.0581 -0.0212 10724 Srimangal 24.3 91.73 22 m 0.0030 0.0237 10705 Sylhet 24.9 91.88 33.5 m 0.0057 41909 Tangail 24.25 89.93 10.2 m -0.0234 11929 Teknaf 20.87 92.3 5 m 0.0242 0.0236 Trends of Temperature For 34 ground measuring Stations of BMD

Trends of Maximum Temp.

Trends of Minimum Temp.

Maximum Temperature Maximum increase: 0.0581 at Shitakunda Minimum increase: -0.026 at Rangpur Minimum Temperature Maximum increase: 0.0404 at Bogra Minimum increase: -0.023 at Tangail

Monthly temperature over Bangladesh (1948-2007)

Month-wise Trends Month Max. Temp. (0C per yr.) Min. Temp. January -0.0142 0.0104 February 0.0000 0.0340 March -0.0117 0.0220 April 0.0121 May 0.0010 0.0052 June 0.0139 0.0103 July 0.0116 0.0075 August 0.0183 0.0081 September 0.0070 0.0031 October 0.0178 0.0078 November 0.0270 0.0289 December 0.0147

Trends of minimum temp. in January Increase 1.04 0C in 100 years

Trends of minimum temp. in February Increase 3.5 0C in 100 years

Average Temperature in January (1948-2007) Daily Minimum Daily Maximum

Effect of Temperature rise on Agriculture In winter season (Nov-Feb), the main crops of Bangladesh are: Boro (rice), Wheat, Potato, vegetables. Increase of winter temperature can reduce the environmental suitability for wheat, potato and other temperate crops grown in Rabi season. It might benefit Boro paddy and kharif crops.

Wheat growing areas and minimum temperature trend map in January Trends of minimum temp Wheat coverage area

Effect on Potato: Temperature derived from MODIS data during January, 2006 Temperature map in January Plantation starts on December Potato Field in Munshigonj

Presently working We are presently working on the future prediction of temperature trends using PRECIS regional climate change model. Climate Change Study Cell has been formed in our university with vision of “to establish itself as the premier knowledge center on climate change risk and adaptation for Bangladesh”. http://teacher.buet.ac.bd/diriwfm/climate/

Conclusion Both daily minimum and maximum temperature shows positive trends over Bangladesh. Increase of daily maximum temp. is 0.63 0C and daily minimum temp is 1.37 0C in 100 years. Maximum increase of daily maximum temp. has occurred in November at 2.7 0C and daily minimum temp. has occurred in February at 3.4 0C in 100 years. Maximum increase of daily maximum temp. has occurred as 5.810C at Shitakunda and daily minimum temp. has occurred as 5.04 0C at Bogra in 100 years. Increase of winter temperature can reduce the environmental suitability for wheat, potato and other temperate crops grown in Rabi season.

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