Climate Change Impacts on Rice Farming Systems in Northwestern Sri Lanka.

Work under Agricultural Model Inter-Comparison and Improvement Program (AgMIP) has led to the development of state-of-the-art climate, crop, and economic models for irrigated rice agricultural systems in Sri Lanka. The climate projections based on CMIP5 show a clear increase in temperature in the mid-twentieth century for a high greenhouse gas concentration pathway. The rainfall shows a slight increase for a preponderance of the 20 GCMs in the CMIP5 archive, with the highest increase for the early phase of the Maha season (October-March). During the Yala season (April to September),  more than half of the models showed a decline, including 4 of 5 GCM that were selected for detailed analysis.   

The DSSAT crop model simulations with climate change scenarios showed relative yields that were lower (by -6 to -15% for the Maha and by -24 to -37% for the Yala). After implementing adaptation strategies relative yields increased for both seasons (0.5 – 6% for Maha and from 67 to 78% for Yala).

Analysis of gains, losses, poverty rates were conducted (with the TOA-MD model) for two villages in the North-Western Kurunegala district- Migalewa (Maha and Yala) and Kadawaramulla (Maha).   The projected climate change brings negative economic impacts for 55-74% and 77-85% farmers during Maha and Yala seasons under the five GCMs.  However, for both sets, poverty rates for the future under a future production system showed a very slight decline-except under GCM: HadGEM2-ES - compared with the current climate under a future production system- Question 2. Adaptation measures led to slight (5-14% ) increase in per capita income in comparison.

Analysis based on scenarios with relatively small rainfall increases show a drop in yields in both seasons, being particularly deleterious in the Yala season. In the latter case, use of shorter-duration varieties, changes in the planting dates and improved cultivars led to substantial recovery of losses. Analysis of climate change impacts on water constrained rice agriculture is underway as this mode accounts for a large majority of cultivation.