The global mean annual temperature at the end of the 20th century was 0.7°C above those recorded at the end of the 19th century. The 12 warmest years in instrumental record have occurred after 1990. Climate extremes such as droughts, floods, rainfall distribution and snowmelt have increased at several places. Reports also indicate that Himalayan glaciers are receding at an increasing pace. The globally averaged temperature of the air above the earth’s surface is expected to rise by 1.4 to 5.8°C over the next 100 years.
The Indian Scenario
At all India level no significant trend emerges from the study of monsoon rainfall during last 100 years, however some regional patterns may be noted. West coast, north Andhra Pradesh and north west India are experiencing increasing monsoon rainfall while east
Madhya Pradesh and adjoining areas, north-east India and parts of Gujarat and Kerala are facing a decreasing trend (-6 to -8 per cent of normal over 100 years). Also rainfall analysis of data of 1140 stations in the country indicated that more than 70 per cent of the stations showed short term fluctuations in annual rainfall for less than 10 years period.
Surface air temperature for the period 1901-2000 indicates a significant warming of 0.4°C especially along the west coast, central India, and interior Peninsula and over northeast India. However, cooling trend has been observed in northwest and some parts in southern India. A season wise temperature trends indicate that maximum increase in temperature was observed in post monsoon (0.7°C) followed by winter (0.67°C) and then pre-monsoon (0.5°C) and monsoon (0.3°C). On the other hand the total frequency of cyclonic storms that form over Bay of Bengal has remained almost constant over the period 1887-1997.
Crops and Climate Change
India’s agriculture is subject to climate variability which is likely to be exacerbated by climate change. The agriculture sector in India contributes 28 per cent of the total GHG emissions primarily due to methane emission from rice paddies, enteric fermentation in ruminant animals, and nitrous oxides from application of manures and fertilisers to agricultural soils. The emissions from Indian agriculture are likely to increase significantly in future due to our need to increase food production. Although detailed zone wise analysis has not been done, broadly, wheat production in the Indo-Gangetic plain zones is likely to be affected negatively while the crops in coastal and Island zones are likely to suffer from sea water inundation. Preliminary calculations to quantify the decrease in production of wheat suggest a likely decrease of 4 to 5 million tons with an increase of 1°C increase in temperature throughout the growing season. Productivity of fruit crops will be affected in the hill zones due to rise in temperature and precipitation. It is thus projected that climate change is likely to negatively impact agriculture including irrigation availability, soil health, pests, crop and livestock production.
Changes in climate are expected to impact Kharif (southwest monsoon) more than Rabi (northeast monsoon). During Kharif in 2020, 10 to 15 per cent reduction in rice yield is expected due to increase in temperature and change in rainfall. Consequently, in 2050, 30 to 35 per cent yield reduction and in 2080, up to 80 per cent yield reduction are expected in Tamil Nadu. Aromatic rice, such as Basmati, being more sensitive to high temperature will experience a reduction of test weight, grain elongation and aroma. GIS studies on prediction of suitability of growing ginger in Orissa and West Bengal, now a highly appropriate region, have shown that these areas would turn hostile with rising temperatures of about 1.5° to 2°C. Coconut yields too are likely to be affected and plains of Karnataka, eastern Tamil Nadu, coastal Andhra Pradesh, Puducherry, West Bengal and Assam were found to be hotspots as per HadCM3 model scenarios of climate change.
Analysis of recent weather data in Himachal Pradesh indicated that the maximum temperature is showing an increasing trend during November to April. This has resulted in a shift of the apple belt upwards. In response new areas of apple cultivation have appeared in Lahaul and Spiti and upper reaches of Kinnaur. Apple productivity in Kullu, Shimla as well as overall average productivity of the State has shown declining trend – average State productivity in 1980-81 was 7.06 tons per ha that decreased to 4.65 tons per ha in 2004-05.
Impact on Soil, Stream Flows and Pests
Scientists point towards greater need for soil conservation in peninsular and central India because of their projected high runoff and soil losses associated with global climate change. A decreasing trend of runoff and soil loss is projected when we move from tropics to the temperate region. Simulation results indicated an increase in mean annual stream flow at several places in 2020 and 2050 under PRECIS RCM scenarios. Though there is increase in annual stream flow, a decrease in monthly stream flow, particularly during summer months (February – June) was projected.
Pest prediction equations in relation to temperature were developed for thrips population in horticultural crops. It was observed that in rose, thrips required 265 and aphids 119 thermal day degrees (TDD) for development under field conditions.
Climate Change and Animal Husbandry
A rise of 2 to 6°C will negatively impact growth, puberty and maturity of crossbreds and buffaloes and time to attain puberty will increase by one to two weeks due to their higher sensitivity to temperature than indigenous cattle. Global warming is likely to lead to a loss of 1.8 million tons in milk production by 2020 and 15 million tons by 2050. The economic losses were projected to be highest in Uttar Pradesh followed by Tamil Nadu, Rajasthan and West Bengal.
Another likely impact may be on the availability of fodder. There is already severe deficit of green fodder and feed for animals which adversely affects the productivity of the animals. Also, there may be increase in the vector borne diseases in animals which even today is a serious problem.
A rise in temperature as small as 1°C could have a rapid effect on the distribution, growth, reproductive cycle, mortality and geographical distribution of fish. Oil-sardine fishery did not exist in the northern latitudes and along the east coast before 1976 as the resource was not available and sea surface temperature (SST) were not congenial. With warming of sea surface, the oil-sardine is able to find preferential temperatures thereby extending its distributional boundaries. The dominant demersal fish, the threadfin breams have responded to increase in SST by shifting the spawning season to cooler months – 35.3 per cent spawning occurred during the warm months (April-September) in 1980 but the number gradually reduced to 5 per cent during the same season in 2004. A similar trend was observed in other species too. The increase in seawater temperature will however be beneficial in certain instances with likely positive effects on major pelagic fishery such as oil-sardine, mackerel and bombay duck. A change in the species composition of fish catch is also expected.
Recent climatic patterns have brought about hydrological changes in the flow pattern of river Ganga which has resulted in erratic breeding and decline in fish spawn availability. As a result the total average fish landing in the Ganga river system declined from 85.21 tons during 1959 to 62.48 tons during 2004. In the middle and lower Ganga, 60 genera of phytoplankton were recorded during 1959, which declined to 44 by 1996, while during the same period zooplankton diminished from 38 to 26. A number of fish species, which were predominantly only available in the lower and middle Ganga in 1950s, are now recorded from the upper cold water stretch up to Tehri. Also, in recent years Indian Major Carps are maturing and spawning as early as March with its breeding season extending from 110-120 days (pre 1980-85) to 160-170 days (2000-2005). As a result, it has been possible to breed them twice in a year at an interval ranging from 30-60 days. A prime factor influencing this trend is elevated temperature especially in West Bengal (location of the study), where average temperature has increased in the range of 0.1 to 0.9°C.
IPCC recently synthesised all available global information in its recent assessment, and concluded that sea level will rise by 0.18 to 0.59 meters by 2100. If such sea level rise takes place in India, impacts on the livelihood of coastal communities will be considerable with vast stretches of coastal lands submerged, making them unsuitable for upland crops and increasing the salinity in aquifers.
Coping with the Changing Climate
The agricultural strategies to manage climate variability should consist of both short term and long term strategies. The short term strategies include the use of available drought/heat tolerant varieties, water harvesting and efficient use of rain and irrigation water and proven agronomic practices that release minimum greenhouse gases, etc. The long term strategies include development of varieties of crops and improved breeds tolerant to extreme weather situations through use
of frontier technologies, development of resource conservation technologies for different agro-climatic zones that use less water and energy and evolving socio-economic safety nets like weather insurance. In addition, an early warning system of climatic risks, and prior development of region specific responses will be useful.
Heat tolerant varieties of crops may be developed in addition to augmenting production; improving land use and natural resource management; building risk management potential through early warning system and crop insurance; establishing regional food security programmes and raising capacity; and recycling waste water and solid wastes. In the specific case of wheat, adaptations such as change in planting dates and crop varieties could help in reducing impacts of climate change. In fact the losses could be minimised to 1-2 from 4-5 million tons if a large number of farmers changed planting time. This however, may not be easy to implement due to constraints associated with wheat planting time in rice based cropping systems.
In the animal husbandry sector the optimal size of livestock population of the country needs to be determined based on the projected requirement of livestock products, availability of feed and fodder resources, land resource availability and environmental sustainability. The estimated requirement of milk, meat and egg by 2020 would be about 160 million tons, 10.58 million tons and 90 billion, respectively. Despite India being blessed with a very large animal population, productivity is low – less than half of the world average and about 10 per cent of what is being achieved in Israel. The focus is on artificial insemination especially of indigenous breeds in cattle which have the capacity to bear stress whether it is heat, humidity or diseases. As far as control of animal diseases is concerned, India is now free from the rinderpest, but the
major challenge is to fight the foot and mouth disease which is causing severe economic losses to the country.
For sustaining production and productivity, the fisheries sector may be able to adapt to climate change by designing fuel efficient fishing craft and gear, developing resources specific fish harvesting techniques for emerging new fishery, acclimatising commercially available cultivable species to the climate change in freshwater and marine ecosystems, and identifying new candidate species for aquaculture having more adaptability towards changes in salinity and temperature regime. Research studies on the possible impacts of climate change on fisheries and aquaculture are in progress in the Central Marine Fisheries Research Institute (CMFRI), Kochi and Central Inland Fisheries Research Institute (CIFRI), Barrackpore covering the coasts and 14 major river systems flowing through 13 agro-climatic zones of India. The productivity of the inland fishery sector is very low, thus additional stress needs to be laid to tackle the problem by increasing productivity in reservoirs, canals, tanks and ponds. Also, while the coastal areas have been over-exploited, there is hardly any exploitation of deep sea marine resources. A proactive deep sea marine fishing policy needs to be in place so that the EEZ is better exploited. For example, tuna fishing is a profitable venture and conversion of the traditional craft into long-line tuna vessels has been fairly successful.
Improved land use management and water management is crucial. 16 tons of soil per hectare per annum is getting eroded. Out of this, 29 per cent is being washed into the sea, and the rest is getting deposited in river beds and fields. Agricultural conservation in such situations is imperative. One such measure would include laser levelling. In western Uttar Pradesh 22 laser levellers were undertaken each costing about Rs 4 lakh. Once levelled, saving of water is to the tune of about 30 per cent, thus leading to more efficient utilisation of water. Also, actual cropped area goes up by about 3 per cent. Another method is what the farmers in Haryana follow – the practice of raised bed cultivation which saves water and fertiliser apart from inhibiting the growth of weeds. Measures are needed to check the decline in ground water table. As per the latest assessment of ground water resources carried out jointly by CGWB and the State Government Departments out of 5723 units (blocks/talukas/watersheds) in the country, 839 units are ‘over-exploited’, 226 units have been categorised as ‘critical’ and 550 ‘semi-critical’.
The National Action Plan on Climate hange envisages effective disaster management strategies, strengthening of communication networks and disaster management facilities at all levels and protection of coastal areas through a concerted focus on early warning systems. There are 8 National Missions constituted under the Prime Minister’s Council, which form the core of the National Action Plan, representing multi-pronged, long term and integrated strategies for achieving key goals in the context of climate change. The Missions are National Solar Mission; National Mission for Enhanced Energy Efficiency; National Mission on Sustainable Habitat; National Water Mission; National Mission for Sustaining the Himalayan Ecosystem; National Mission for Green India; National Mission for Sustainable Agriculture; and the National Mission for Strategic Knowledge for Climate Change. The objective of the Missions is to enable the nation to adapt to climate change and enhance the ecological sustainability of India’s development.
The most vulnerable section in the climate change scenario will be the rural poor, especially women, children and the old, facing scarcity of water, reduction in yield and malnutrition. A force of ‘Climate Risk Managers’ may be created at all levels. At the village level/block level, they should be able to communicate the strategies required to manage climatic risks on a real time basis to the farmers. At the same time they should be able to liaise with other related functionaries, including National Disaster Management Authority, Indian Meteorology Department and Department of Agriculture and Animal Husbandry, and insurance officials at district and state levels.
Although the problem of climate change is global, India needs local solutions. Agriculture is our backbone, feeding over one billion people, which makes food security our prime most concern. Out of 75 million persons added world over to the ‘hungry’ during 2007, over 30 million are from India.
Climate change offers limited response options, one being mitigation, and the other adaptation. India needs to opt for adaptation. With a total of 141 million hectares of cultivable land out of which 85 million hectares or 60 per cent falls under the rainfed and dry land area category, India needs to shape its policies to cater to changing climatic scenarios. Adaptations can be at four levels – farm, technological, social and institutional. Cropping systems and agronomic interventions like soil conservation, crop rotation, intercropping, and zero tillage along with the promotion of less water demanding crops needs to be urgently underway.
Excerpts from Impact of Global Climate Change on Agriculture and Allied Sectors in India, Ministry of Agriculture, 2009