Study on the impact of climate change on the production of BR11 aman rice in Bangladesh

Abstract

Agriculture is one of the most important sectors of the world which is going to be threatened by the change of climate, specially the rise of global mean temperature. That is why; the 21st conference of parties (COP21) of the Intergovernmental Panel on Climate Change (IPCC) has come with the aim of limiting global temperature to 1.5°C within the year 2020.

Bangladesh is an agrarian country and rice is the staple food of this country. Agriculture contributes to 35% of the GDP and 70% of the labor force in Bangladesh. With the present population growth rate of 2 million per year, the total population of Bangladesh would be 238 million by 2050. It will require more than 55.0 million tons of rice by the year 2050 to meet this demand. Aman is the rice variety that covers most of the lands of the country and it is so important because of its growing season at Monsoon period. BR11 cultivar of Aman was used for studying the impact of climate change on the production of rice.

The impacts of climate change on the production of Aman rice in Bangladesh have been evaluated using the DSSAT (Decision Support System for Agrotechnology Transfer) crop modelling software. The model was calibrated using BR11 variety of Aman rice for the years 2007-2010 and validated for 2011-2014 incorporating BBS (Bangladesh Bureau of Statistics) data with statistical parameter RMSE (Root Mean Square Error). Eight genetic coefficients for BR11 variety of Aman rice are the calibration parameters of Aman rice in DSSAT 4.6. Impact of future climate is analysed considering baseline period of 30 years from 1981-2010. The future yield was predicted for the near future or 2030’s (2021-2050) and the far future or 2080’s (2070-2099). The historic weather data was taken from the meteorological stations of Bangladesh Meteorological Department (BMD) while the projection was made taking seven bias corrected ensembles of Regional Climate Models provided by CORDEX (The Coordinated Regional Downscaling Experiment) for South-Asia region. The soil profile data was integrated in DSSAT by extracting data from 14 soil databases of Bangladesh available in WISE 1.1 soil database.

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From the predictions it is observed that, most of the districts would have negative yield in future, reaching over 15% decrease in some regions. The mean decrease of Aman yield at the 2030’s (2021-2050) and 2080’s (2070-2099) are found to be 5%-8% and 8%-13% respectively. The maximum temperature rise would exceed 1.5°C in 2030’s and 4°C in 2080’s whereas the minimum temperature would rise up to 4.5°C in 2080’s. This rise in daily temperature over the growing period of Aman rice indicates the adverse impact of temperature on crops. However, the increasing amount of Carbon dioxide increases crop yield up to a certain limit. But, it is not significant enough in comparison to the negative impacts of the rise of temperature. Basing on the sensitivity analysis, almost all the regions have an increased yield in the elevated CO2 emission than that in the fixed CO2 emission in 2030’s and 2080’s. However, the range of unpredictability in rice yield has increased with the elevated CO2 emission. This might indicate the complex correlation between temperature and elevated CO2 emission in the yield of crop.

The outcome of the study indicates that the increase in global mean temperature would significantly decrease the yield of Aman rice. It is high time we took necessary adaptation and mitigation measures to save our valuable crop.