Climate Change: Indian Tea impacted by excessive chemicals, major threat to Northeast

After losing opportunity of ramping wheat export due to global food crisis due to Russia-Ukraine war, now Indian tea producers’ chances to capture tea export market on back of falling produce by crisis-hit Sri Lanka has also hit a roadblock.

Reportedly, Indian tea consignments have been rejected by several countries because of pesticides and chemicals above the permissible levels early this year in April-May. Tea producers have to conform to Maximum residue level (MRL) of chemicals set up by the Food Safety and Standards Authority of India (FSSAI). MRL, a trading standard, safeguards that the residue levels do not pose any risks to consumers. Till present, FSSAI has notified MRL for 34 pesticides.

However, traders blame changing environmental conditions for increased usage of chemicals for maintaining quality as well as the quantity. Climate change started changing the quality of the tea leaves and erratic rains and strong winds began depleting the soil. By 2012, green leaf productivity had declined by 41.97% compared to 1993 figures and 30.90%, compared to 2002. By 2021, according to the latest data provided by the Tea Board, the production of Darjeeling tea fell to 6.19 million, the lowest on record.

Impact of Climate Change

Several studies have concluded that the climate change is expected to decrease not only the quality of tea, but also the quantity of tea production in warming world. Temperature rise, increase in ambient CO2 concentration, erratic rainfall events, longer dry periods, more hail, and cyclonic storms, and pests and diseases are becoming more resistant.

The rainfall pattern and the average and maximum temperatures in all main tea production regions seem to have undergone marked changes in the recent past. According to a study, ‘Global warming and Tea Production’, the tea plants are affected by both excesses and shortages of water and suffer from increased climatic stress. Changing climate conditions impact the concentration of secondary metabolites, which are most important for the quality of tea. The dilution of phytochemicals as a consequence of more frequent extreme rains has resulted in the changes of the tea taste.

Another study ‘Effect of Climate Change on Production of Darjeeling Tea’ stated, environmental factors are responsible for the development of seasonal quality of tea leaves. It is also a known fact that pest and disease incidence is related to the weather pattern. Therefore, temperature rise, increase in ambient CO2 concentration and extreme rainfall events (heavy rainfall and drought) brought about by climate change (global warming) can affect production and quality of tea.

Basic Environmental changes: Pronounced changes in temperature, precipitation, and relative humidity are changing basic parameters necessary for growth and development of tea, such as soil pH, water content, organic matter, nutrient availability, pest and disease management, ecological systems around tea gardens and eventually tea processing.

Shift of tea production areas: With increasing temperatures, especially a rise in the minimum temperature, the tea growing area would be extended to higher latitudes and higher altitude ecosystems. This might be beneficial for tea production in relatively cold climate regions, but would have a negative effect in lowland and tropical areas as they may become unsuitable for tea cultivation in the future. This could trigger a shift in suitable locations for the cultivation of some varieties if high-quality tea is to be obtained.

Tea plucking duration: The temperature increase in subtropical areas with distinct seasons will extend the duration of growing and plucking. It is reported that the number of days warmer than 10°C, which is regarded as the starting temperature for tea sprouting, may increase by 15 days if the annual mean temperature increases by 1°C. With an increase in spring temperatures, the tea budding time will be advanced and the harvest can begin earlier.

Carbon-dioxide concentration: The photosynthesis would acclimatise to high CO2 concentration, so that the increase in yield would not be as great as expected since CO2 concentration increases gradually with long-term climatic change. In addition, as the concentration of CO2 increases, other plant growth limiting factors such as a shortage of nitrogen and microelements will appear, further reducing the benefit of the CO2 concentration increment to tea yield.

Pests and diseases:  Warmer weather helps insects and pathogens to survive in winter, which is a critical time for their reduction, and thus helps to shorten the damaging period by increasing the number of annual generations and reproduction rates in some pests.

Soil quality: An increase in temperature speeds up the microbe depletion of soil organic matter while reducing the time needed to release nutrients from chemical fertilisers. Intense daily precipitation may cause severe flooding or landslides, which remove fertile top soils. The enrichment of CO2 and other air pollutants such as SO2 and NO2 will cause strong acid precipitation that further increases soil acidity.

Northeast India- The most impacted

The main tea-growing areas of Northeast India, Assam and West Bengal, have registered steady increase in the average minimum temperature that risen by about 1.3°C over the last 100 years. However, the annual precipitation has steadily declined. Annual precipitation in the South bank region at the TTRI of Assam has declined by more than 200 mm in the last 96 years.

Further, models derived by WorldClim and IPCC4 found that the average temperature may increase by 2°C in Northeast India in 2050, while there will be a little variation in the rainfall pattern as compared to today.

Ongoing changes on account are likely to result in negative economic and social consequences, particularly for tea farmers, workers on tea estates, and tea traders. Assam contributes around 17% of world tea production, supporting the livelihoods of around 1.2 million laborers. Tea planters need to look for climate change adaptation strategies for their future tea production. Scientists and researchers have called for changes in management practices to adapt to the changing climate.

 

Climate Change, Global Warming, Tea plantation in India