Climate change refers to any change in climate overtime whether due to natural variability or as a result of human activity. Climate change is one of the global burning issues that has shaken the global political arena to focus on this vital issue that may endanger the very existence of mankind and other species on blue plant. Warming has caused melting of polar ice and increase of ocean water levels. It has produced shorter and warmer winters, with earlier arrival of spring temperatures and later onset of winter conditions. Unable to cope up with the current environmental stresses such as drought and water stress, the poor will be vulnerable to climate change and will find it difficult to adapt. The agriculture activities globally contribute about 13.5 % while as India contributes 28 % through agriculture. The impact of climate change on the poorest people, which may exceed five hundred million in India, is rarely the central issue in all the debates on climate change. The central issue for policy makers seems to be the likely impact of any climate mitigation measures on economic growth. However, economic growth alone will not insulate the poor against the adverse impact of climate change. High growth rates in the past decade have not made any significant impact on the quality of life of the poor. The poor in India are already exposed to severe water scarcity, water pollution, fodder and fuel wood scarcity, land degradation desertification, droughts and floods. Warming has caused melting of polar ice and increase of ocean water levels. It has produced shorter and warmer winters, with earlier arrival of spring temperatures and later onset of winter conditions.
Ever increasing emission of green house gasesis a natural process that plays a major part in shaping the earth’s climate. It produces the relatively warm and hospitable environment near the earth’s surface where humans and other life-forms have been able to develop and prosper. However, the increased level of greenhouse gases (GHGs) carbon dioxide (CO2), water vapor (H2O), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6), and indiscriminate cutting of trees due to anthropogenic activities has contributed to an overall increase of the earth’s temperature, leading to a global warming. According to IPCC, the three main causes of the increase in greenhouse gases observed over the past 250 years have been fossil fuels, land use, and agriculture. Agriculture is itself responsible for an estimated one third of global warming and climate change. It is generally agreed that about 25 per cent of the main greenhouse gas, carbon dioxide, is produced by agricultural sources, mainly deforestation and burning of biomass. Most of the methane in the atmosphere comes from domestic forest fires, wetland rice cultivation and waste products, while conventional tillage and fertilizer use account for 70 per cent of the nitrous oxides. The Food and Agriculture Organization has estimated that meat production accounts for nearly a fifth of global greenhouse gas emissions. These are generated during the production of animal feeds. Ruminants particularly cows, emit methane which is 23 times more effective as global warming agent than carbon dioxide.
Table-1:- Major contribution of Green House Gases
|Gas||% contribution||Global warming potential|
Reduced crop yield:-Agriculture will be impact by climate change in several ways. There will be reduced crop yield. For example, an increase of temperature from 1 to 4o C can reduce grain yield of rice by 0-49% potato by 5-40%, green gram by 13-30%. The climate change impact on the productivity of rice in Kashmir (India) has shown that with all other climatic variables remaining constant, temperature increases of 1 °C, 2 °C and 3 °C, would reduce the grain yield of rice by 5.4%, 7.4% and 25.1%, respectively. Soil temperature affects the rates of organic matter decomposition and release of nutrients. At high temperatures, though nutrient availability will increase in the short-term, in the long-run organic matter content will diminish, resulting in a decline in soil fertility. Climate change can shorten rabi season and decrease yield.
Impact on temperate fruit crops:- Temperate regions of the world are going to be the first causality in view of the ever increasing global mean temperature that may effect the livelihood of agrarian temperate countries to a larger extent. The potential effects of global warming are on chill requirement, flowering time, risk of frost, length of growing season, maturity/ harvest, fruit quality. The predominant effect of global warming is increase in evapotranspiration which will increase the demand for irrigation. Higher temperature affects pollen viability and has resulted in flower bud drop in peach and apricot. Prolonged exposure to direct sunlight causes a rise in surface temperatures in fruit and thus results in rapid ripening and other associated events. One of the classic examples is that of grapes, where berries exposed to direct sunlight ripen faster than those ripened in shaded areas. Temperature is the most significant factor affecting antioxidant activity in vegetables and fruits. Generally, rise in temperature accelerates initiation reactions, and hence results in decline of existing and augmented antioxidant activities. Antioxidants in fruit and vegetable crops can also be altered by exposure to high temperatures during the growing season. The authors verified that higher temperatures inclined to reduce vitamin content in fruit and vegetable crops. Many fruits, including apples, cranberries, blue berries and nuts require at least 1000 hours below 450 F each winter to produce good yield. Under the high emissions, winter temperature in temperate areas may not be cold enough to consistently to meet these requirements
Chilling requirement is very important for temperate fruits for bud formation. Trees develop their vegetative and fruiting buds in summer and these buds will remain dormant until they have accumulated sufficient chilling requirement. However due to the ongoing global warming the temperate fruits failed to receive sufficient chilling requirement which leads to many symptoms like delayed leaf formation, reduced fruit set and reduced fruit quality. The increase in temperature causes low viability of pollen grains and ovule, pollen desiccation and death of pollinators. Spring events such as bud break on trees and breeding of toads and birds are happening about 5 days earlier with each decade. Some authors have reported a trend towards an increased risk of spring frost, although this is not exclusively attributed to climate change, but also to spread of early flowering cultivars or the expansion of growing areas into region more susceptible to frost.
Shifting in farming areas:- Rising sea levels owing to climate change would force communities in low line coastal areas and river deltas to move to higher ground level. Similarly, increasing frequency of droughts due to climate change would force farmers and pastoralists, who rely on rain fall to raise their crops and livestock, to migrate to areas in search of land and water. This migration/ displacement of people would result in direct conflict and competition between migrants and established communities for access to land.
Mehraj ud Din Sheikh, Ex-Deputy Director SAMETI, SKUAST-Kashmir.
Dr. H .A. Malik, Asstt Prof. SKUAST-Kashmir and Ex-Consultant Planning Commission, GoI
Dr. Mehraj Ud Din Khanday, Research Scholar, presently working in networking project funded by Department of Science and Technoloy, GoI
Ejaz A Parry, Research Scholar SKUAST-Kashmir.