Climate Change Impacts Darjeeling

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Landslides in the Darjeeling hills are a double threat. They destroy trees, sometimes by the tens of thousands, and they ruin roads, drainage systems and bridges. The area pictured near Giddapahar Tea Estate is extremely dangerous. (Photo courtesy Rajiv Lochan)
Darjeeling is not immune to the effects of climate change, which has already negatively impacted tea cultivation on several levels. Weather reflects short-term conditions of the atmosphere, while climate is the average daily weather for extended periods of time and place. Wedged and uplifted by an ongoing collision of the immense Nepal and Bhutan Himalayas, with near vertical ascents, glacier-fed rivers and remarkable diversity in soil, Darjeeling experiences extremes in weather as the norm—which is why changing climate is of great concern. During the past decade yields have fallen significantly. In 1994 production exceeded 14 million kilograms, but by 2016 that total had fallen to 8.44 million kilograms (year ending March 2017). Last year was an anomaly due to an extended strike by workers during which most of the precious and profitable second flush crop was lost. The harvest year ending March 2018 saw a 50 percent decline in yield offset somewhat by strong pricing due to scarcity and an excellent first flush. During much of the year Darjeeling is cool and dry with occasional winter dustings of snow—not blizzards. Then torrents of monsoon rains arrive in summer. “The rainy season has shortened. Heavy rains occur occasionally, resulting in cloud bursts that saturate land bereft of vegetation,” writes Raju Lama, a Darjeeling grower and owner of Darjeeling Tea Leaves. Over time the hours of sunshine have risen from 3.03 to 5.71 per day. In the past, annual monsoons arrived on schedule and appeared less violent, but rising temperature poses the greatest concern to tea growers. The West Bengal State Climate Action Plan is a coordinated effort to address a range of concerns in the region, said Mrityunjay Coubey at a media workshop on climate change in June. The drier, hotter climate “affects carbohydrate assimilation, respiration and evapotranspiration of tea plants, pest and disease infestation, drought and heavy rainfall incidence and soil degradation,” he said. The formation of Darjeeling’s famous polyflavinols is directly related to cold air trapped below the peaks of the Kanchenjunga Himalayas, explains Rajiv Lochan, founder of Lochan Tea and a long-time Darjeeling grower. Temperate Tea
Map of Darjeeling Terrain (Google)
Tea thrives under a dome of cool air that rests over a region defined by five valleys: Darjeeling, Mirik, Teesta, Rambang, and Kurseong—all with different weather patterns. Yet they share a single concern: keeping temperatures between -7 and 86-degrees Fahrenheit (18°- and 30°C). According to a study by the Darjeeling Tea Research & Development Centre, during the last 20 years, temperatures in the region have risen by one degree Fahrenheit (0.51°C); the total annual rain-fall has decreased by 60 inches (152.50 cm), and, there has been more than a 16 percent reduction in relative humidity. In early 2017, prior to the strike, Ashok Kumar Lohia, chair of the Chamong Tea Group, which operates 13 Darjeeling estates, told Down To Earth magazine that “erratic weather and delayed rains cost nearly 15 percent loss of production during the first flush.” Plucking rounds that once averaged seven days are now stretched to 10-12 days, due to a shortage of labor and variations in rainfall. Warming air due to changes in climate are the most noticeable and most complicated threat to the unique taste and great value associated with tea from this region in West Bengal, says Lochan. “The Fengshui of Darjeeling makes it most susceptible to global warming as it faces the wrath of hot winds coming from the heated plains of the Ganga (Ganges) River,” explains Lochan. Gardens are planting tall trees to shade the tea and doing their best to raise the humidity locally in micro-environments near streams, springs, and small reservoirs. Damage to Infrastructure
A major landslide that destroyed Hill Cart Road below Mahanadi, the main road into Darjeeling, required two years to rebuild. (Photo courtesy Rajiv Lochan)
The newly formed Darjeeling “hills” that rise from 500 feet (150 meters) on the Terai plateau to 11,930 feet (3,636 meters) at Sandakphu, sit on soils that tend to slide due to the vertical slopes made of golden and silvery mica-schists, quartzites, biotite-kyanite and coarse-grained gneiss from the pre-Cambrian period. The first landslide that disrupted the region was in 1899, killing 72 and another in 1934 near Bihar following a major earthquake, with others in 1968 and 1980 but until recently there were relatively few fatal movements of earth. In July 2015 40 people lost their lives to landslides, a trend more noticeable since 2003. In 2012 heavy rains triggered landslides that caused extensive damage to six tea gardens in Darjeeling and Kalimpong. Lochan mentions “mechanical damage due to global warming in the lower ranges severely manifested in the huge landslides on Hill Cart Road below Mahanadi (pictured). Long stretches of road have disappeared near Gyabari and Jogmaya. Damage was so extensive it took two years to repair, he said. At Ambootia an organic and biodynamic estate located near Kurseong, a landslide in October 1968 wiped away the whole hydraulic water pressure system below the town. It was the biggest landslide ever recorded along the entire Singalila range – an indication of the further erosion of prehistoric Darjeeling, says Lochan. Giddapahar and Jungpana are almost extinct routes to posterity due to disturbance in water-soil mechanics, he added. Roads along the Rungneet River where it joins the Teesta River are washed out from flooding. One remedy is to install drains. Harvesting rainwater holds great promise as local reservoirs can then be tapped to irrigate. Darjeeling receives only 4 to 5 percent of its total annual rainfall between October and March. Namring Tea Estate in eastern Darjeeling taps local springs in a network that provides nearly 80 percent of the garden’s needs. Balasun Estate (under Jayashree Tea & Industries) in Kurseong sub division of Darjeeling is planting vetiver along its garden. “It is a fast-growing wonder grass with a strong fibrous root system that penetrates and binds the soil to a depth of 3 metres and checks soil erosion on the slopes,” said Ajit Rai, the manager of the estate. Additionally, vetiver hedgerows can slow the run-off water down the hills, which then percolates into the deep sub-soil through the root system of the grasses, thereby conserving soil moisture. Guatemala grass and citronella are planted to prevent soil erosion and inhibit weed growth. Ravaging Pests Estates located nearest large forested areas report significant increase in the appearance of Tea Mosquitoes, a fatal foe of quality tea. These insects (Helopeltis) attack young leaves, sucking sap and injecting a toxin through their saliva that kills the tissue surrounding the bite, eventually resulting in the death of the leaf. Babu, deputy director of research and senior scientist at the Tea Research Association, North Bengal, explains “shifts in rainfall have particularly increased the incidents of the tea mosquito bug in the late monsoon and autumn seasons.” Organic gardens that rely on natural plantings and beneficial bug protection are having a difficult time, said Lama. “Pest attacks are resulting in loss of crop and increased spending in pest control especially for organic certified tea gardens,” he said. Treatment regimens now begin with prevention efforts at the onset of the dry season. In the past, garden managers waited until the monsoon. New Varietals Show Promise Installing irrigation systems, delaying pruning until May and June (instead of trimming the trees in December and January) and applying organic cuttings and manure are ways of coping with weather but new drought- and pest-resistant varietals are needed to adjust to a new climate. The Tocklai Tea Research Institute (TTRI) in Jorhat, Assam, has been developing new clones and breeding drought-resistant varietals from seeds since 2012. The drought-resistant varieties are hardy and make good tea, said TRRI’s A.K. Barooah. “They not only withstand the stress of climate but also improve productivity and quality,” he said. The institute has developed 27 varietals suited to Darjeeling’s altitude and rainfall patterns that vary by valley. “The sowing of drought resistant plants like B157, P312, T78, AV2 are really helpful as the spells of drought are becoming longer in the hills,” according to tea scientist Choubey. Lochan is hopeful all these efforts will preserve the unique qualities that make tea from Darjeeling so unique. Now is the time to commission a study of the changing flavour profile due to shifting rain and drought patterns in the whole of Darjeeling hills, said Lochan. Agricultural research, hard work and a willingness to accept that change is in the wind will win out, he said. “Luckily Darjeeling’s complex flavors are seemingly improving in the recent times – at least I feel so having exposure of 45 years in Darjeeling,” he said. Sources: Down To Earth, The Quint,