GUWAHATI, July 12 - The impact of climate change is visible at several locations across Assam, including its tea-growing regions.
This was the observation made by a team of experts engaged by the Food and Agriculture Organisation (FAO) of the United Nations in a report in 2016, which has become very relevant today.
Tea scientists here, while corroborating this report, maintained that even though the pre-monsoon rainfall was quite high this year with more number of rainy days in the Upper Assam tea-growing areas, rainfall started decreasing since June after the onset of monsoon. This year, the number of rainy days and total rainfall amount during last June were comparatively less against the month’s normal rainfall.
The tea industry here is seriously worried as to what is in store in the days ahead, said the scientists.
The ‘Report of the Working Group on Climate Change of the FAO Intergovernmental Group on Tea’ prepared by RM Bhagat, KZ Ahmed, N Gupta and RD Baruah of India, MA Wijeratne of Sri Lanka, John K Bore and Darl W Nyanbundi of Kenya and Wenyan Han, Xin Li, Peng Yan and GJ Ahammed of China, stated that about 100 years’ longtime trend analyses revealed decline of over 200 mm in North East India’s annual rainfall. Besides, there is visible rise in its minimum temperature.
The report pointed to another important aspect, the increasing concentration of atmospheric carbon dioxide from approximately 315 parts per million (ppm) in 1959 to a current atmospheric average of approximately 390 ppm plus.
Trend analysis of rainfall from NE India’s tea-growing regions show a steady decline in the annual rainfall. Analysis of annual total rainfall data of 96 years of the South bank region at the Tocklai Tea Research Institute (TTRI), Assam, indicates that the annual rainfall in this region has declined by more than 200 mm. The declining trend of precipitation is more prominent during the post-2004 period.
In several cases, the total precipitation was found to be below normal, especially over central and eastern Assam. This is a matter of concern, as central and eastern Assam have large areas under tea plantation and they produce the highest quantity of tea in Assam, the report said.
Here, annual average temperatures have also shown a steady increase. It has been estimated that in the last about 100 years, the average minimum temperature has increased by about 1.3 degrees Celsius in this region.
The study of the temperature pattern of Assam for the period between 1993 and 2012, both annually and for the growing season, indicates that both the annual and seasonal maximum temperature remained above ideal in many instances, though no distinct trend in the maximum temperature was found.
However, the minimum temperature shows a very clear increasing trend all over Assam, which will have implication on tea production levels.
Tea bushes’ vulnerability to pest infestation also increases with the rise in temperature. Large tea plantation areas in Assam and North Bengal are seen suffering severely from crop loss due to the outbreak of tea mosquito bug, looper caterpillar and red rust disease during the recent years.
Over time, these changes are feared to have adverse implications on tea, making some traditional tea-growing areas unsuitable for tea growing.
The long-term scenario mapped, using spatial analysis, shows that the annual total precipitation is likely to decrease all over Assam, except in some areas of Cachar (Barak Valley) areas, where the annual total precipitation may increase.
The average annual maximum temperature in the region does not show a specific trend. Rather, until 2080, it is likely to experience a decreasing trend. However the analysis shows that post-2080, sharp increasing trends will be observed, particularly in southern, middle and parts of Upper Assam areas, said the report.