Assessment of Uncertainty Cascaded through Climate and Crop Model Simulations for Rice Crop over Thanjavur Region of South India.

Assessment of uncertainty cascaded through climate and crop model simulations for rice crop over Thanjavur region of South India

Geethalakshmi Vellingiri¹, Paramasivam Ponnusamy¹, Ramaraj Palanisamy¹,

Bhuvaneswari Kulanthaivel¹, Lakshmanan Arunachalam¹,  Sonali Mcdermid²

 

¹Tamil Nadu AgriculturalUniversity, Coimbatore, Tamil Nadu, India

²NASA Goddard Institute for Space Studies, New York, NY, USA

 

A study was undertaken to assess the uncertainty cascaded through climate and crop model simulations for rice crop over Thanjavur region of South India, under AgMIP protocols. Uncertainty in climate models were studied through 20 GCMs that used delta approach to produce weather variables. To study the impact of projected climate on crop yields, outputs from 5 climate models viz., CCSM4, GFDL-ESM2M, HadGEM2-ES, MIROC5 and MPI-ESM-MR were utilized in crop model simulation through DSSAT and APSIM. This integrated assessment was done for near (2011-2039), mid (2040-2069) and end century (2070-2099) time slices. Attempt has been made to sort out possible adaptation strategies to reduce the impact of changing climate. The strategies such as altering sowing window and supplemental fertilizer application were tried for rice crop.

  The deviation in weather variables between each time slices and the base years (1981-2010) were calculated for ascertaining the uncertainty. Irrespective of the models, scenarios and time slices, the maximum and minimum temperatures are projected to increase with seasonal variations. With certainty, the projected increase in maximum and minimum temperature for Thanjavur is 0.3 to 4.6 ºC and 0.2 to 5.2 ºC respectively. Rainfall is projected to vary between a decrease of -15.3 to an increase of +80.7 per cent during 21^stcentury. Rainydays had less variation compared to rainfall, about -6.7 to +16.2 per cent change is projected for the future time slices.

On comparing the monsoon seasons, SWM is projected to have a higher increase in both maximum and minimum temperature than NEM, similar to the current trend. Rainfall is projected to increase more in NEM than in SWM, while, there is a small increase in number of rainydays is expected for SWM with no change in NEM, indicating more extreme rainfall events during NEM season in the future. The future yield of rice crop is impacted under future climate conditions (-3.4 to -39.2 per cent) with current cultivation practices. Adaptation practices such as altering the sowing window and supplemental fertilizer application can be successfully employed to minimize the impacts of climate change on rice.