Tea, rubber and coconut comprise the major plantation and agro-processing industry in Sri Lanka. These play a vital role in the economies of many Asian countries. In Sri Lanka, these two sub-sectors contribute 15% of the total export revenue to the country (Central Bank, 2001) and employ more than a million people.

Sri Lanka has a tropical climate with the annual average temperature lying in the range 26-30 oC in the plains where coconut is grown, and in the range 16-20 oC in the hills where tea is grown. The annual rainfall in the coconut growing region is in the range 1,000 - 2,500 mm, while that in tea growing region, is in the range 2,500 - 5,000 mm. Being rain-fed plantation crops, the production of coconut and tea is greatly influenced by the weather and climate. The variations in temperature and rainfall pattern have been identified as the most influential climatic factors affecting productivity. Particularly, dry weather conditions set severe limitations to growth and yield in both these crops.

Analysis of daily rainfall during 1962-1997 of eighteen locations representing four agro-ecological regions of coconut growing areas in Sri Lanka has shown that in addition to the significant decline (P<0.05) of both amount of annual rainfall and number of rainy days, the rainy seasons has changed (Peiris, 2000).

In the tea sector, Wijeratne (1996) found based on laboratory simulated growth curves combined with temperature rise scenarios, that the growth showed a positive response up to 22oC. Thereafter, there was a negative response at higher temperatures. Humidity also plays an important role with the wet season showing a higher growth than the dry season, again the actual rates depending on the clone. Tea is mainly gown under cool climates and any rise in the temperature would adversely affect the productivity. Forewarning of upcoming dry and wet seasons can be use to provide various mitigation options. For example, the pruning of tea leaves can be reduced, shade can be provided and mulching of land could be undertaken in anticipation of dry or hot conditions. In anticipation of wet seasons, soil erosion measures can be put in place, harvesting can be appropriately scheduled and renewal planting can be undertaken.

Relevance to Decision Making

60,000 ha of land (approximately 10% of the total area under coconut and tea) have already been abandoned due to marginal productivity. By implementing adaptation options, it may be possible to bring them back under production. The role of climate in the current decline in productivity of some coconut and tea land can be identified. If the adaptation measurers are not feasible, the government may be compelled to adopt alternate options such as diversification of land into other crops or timber or fuel wood plantations or diversification into other areas of economic activity to bring in lost revenue from tea and coconut.

  Sri Lanka has already undetaken a National Assessment on Climate Change. However, the impacts on the plantation sector is not sufficiently detailed to support policy making and adaptation measures. These shortcomings would be addressed through this project.