Impact on Agriculture
According to Elucidation of the 4th National Report submitted to UNCCD Secretariat, 2010, Ministry of Environment and Forests, GoI, http://moef.nic.in/modules/divisions/desertification-cell/
According to Ecological farming: Drought-resistant agriculture (2010), which has been produced by the Greenpeace,
• Biodiversity and a healthy soil are central to ecological approaches to making farming more drought-resistant.
• Over 60% of the world’s food is produced on rain-fed farms that cover 80% of the world’s croplands. In sub-Saharan Africa, for example, where climate variability already limits agricultural production, 95% of food comes from rain-fed farms. In South Asia, where millions of smallholders depend on irrigated agriculture, climate change will drastically affect river-flow and groundwater, the backbone of irrigation and rural economy.
• There will be a drop in precipitation of up to 10% in South Asia by 2030, accompanied by decreases in rice and wheat yields of about 5%.
• According to a review by the Food and Agricultural Organisation (FAO) in the 1990s, about half of the cultivable soils in India were degraded, and the situation has not improved. Since World War II, soil degradation in Asia had led to a cumulative loss of productivity in cropland of 12.8%
• Soil degradation, mainly the decline both in quality and quantity of soil organic matter, is one of the major reasons linked to stagnation and decline in yields in the most intensive agriculture areas in India, such as Punjab.
• Over-application of nitrogen fertilisers (usually only urea), common in Punjabi farms and influenced by the government’s subsidy system on nitrogen, is not only causing nutrient imbalances, but also negatively affecting the physical and biological properties of the soils.
• Burning rice straw after harvest, now a widespread practice in many places of the Indo Gangetic Plains of India, is also causing large losses of major nutrients and micronutrients, as well as organic matter
• Another common detrimental effect of the excessive use of nitrogen fertiliser on soil health is acidification, and the impact it has on soil living organisms, crucial also for natural nutrient cycling and water-holding capacity.
• Some varieties of wheat developed during the Green Revolution have only short roots – decreasing their capacity for drought tolerance
• Increasing temperatures and less and more erratic rainfall will exacerbate conflicts over water allocation and the already critical state of water availability.
• In 2007, MAS 946-1 became the first drought-tolerant aerobic rice variety released in India. To develop the new variety, scientists at the University of Agricultural Sciences (UAS), Bangalore, crossed a deeprooted upland japonica rice variety from the Philippines with a high yielding indica variety. Bred with MAS, the new variety consumes up to 60% less water than traditional varieties. In addition, MAS 946-1 gives yields comparable with conventional varieties
• In 2009, IRRI recommended two new drought-tolerant rice lines for release, which are as high yielding as normal varieties: IR4371-70-1-1 (Sahbhagi dhan) in India and a sister line, IR4371-54-1-1 for the Philippines. Field trials in India are being reported as very successful, with the rice tolerating a dry spell of 12 days.
• Agriculture will not only be negatively affected by climate change, it is a substantial contributor to greenhouse gas emissions. However, by reducing agriculture’s greenhouse gas emissions and by using farming techniques that increase soil carbon, farming itself can contribute to mitigating climate change
• In the race to produce larger industrial monocultures fuelled by agrochemicals and massive irrigation, the diversity of plant traits available to cope with little water in industrial cultivated crops has been reduced.
• In sub-Saharan Africa, something as simple as intercropping maize with a legume tree helps soil hold water longer than in maize monocultures.
• Scientists have computed that “agricultural losses in the US due to heavy precipitation and excess soil moisture could double by 2030”.
• Scientists now believe that practices that add carbon to the soil, such as the use of legumes as green manure, cover cropping, and the application of manure, are key to the benefits of increasing soil carbon in the practice of soil conservation and reduced tillage.
• It has been shown that a combination of harvesting 25% of the run-off water combined with reducing evaporation from soil by 25% could increase global crop production by 20%.
• Healthy soils rich in organic matter, as the ones nurtured by agroecological fertilisers (green manures, compost, animal dung, etc), are less prone to erosion and more able to hold water.
• Organic matter improves the activity of micro-organisms, earthworms and fungi, which makes the soil less dense, less compacted and with gives it better physical properties for storing water.
• Mulching with crop residues, introducing legumes as cover crops, and intercropping with trees all build soil organic matter, thus reducing water run-off and improving soil fertility.
• Many fungi associated with plants (both mycorrhizal and endophytic species) increase plant resistance to drought and plant water uptake.
According to the Climate change, sustainable development and India: Global and national concerns by Jayant Sathaye, PR Shukla and NH Ravindranath, Current Science, Vol. 90, No. 3, 10 February 2006, http://www.iisc.ernet.in/currsci/feb102006/314.pdf:
Due to climate change, the hydrological cycle is likely to be altered and the severity of droughts and intensity of floods in various parts of India is likely to increase. Further, a general reduction in the quantity of available run-off is predicted.
Simulations using dynamic crop models indicate a decrease in yield of crops as temperature increases in different parts of India. However, this is offset by an increase in CO2 at moderate rise in temperature and at higher warming, negative impact on crop productivity is projected due to reduced crop durations.
Climate impact assessments using BIOME-3 model and climate projections for the year 2085 show 77% and 68% of the forested grids in India are likely to experience shift in forest types under A2 and B2 scenario, respectively. Indications show a shift towards wetter forest types in the northeastern region and drier forest types in the north-western region in the absence of human influence. Increasing atmospheric CO2 concentration and climate warming could also result in a doubling of net primary productivity under the A2 scenario and nearly 70% increase under the B2 scenario.
Malaria is likely to persist in many states and new regions may become malaria-prone and the duration of the malaria transmission windows is likely to widen in northern and western states and shorten in southern states.
Globally, about 1900 Mha of land are affected by land degradation, of which 500 Mha each are in Africa and the Asia-Pacific and 300 Mha in Latin America. Climate change leading to warming and water stress could further exacerbate land degradation, leading to desertification. The United Nations Convention to Combat Desertification (UNCCD) aims to address the problem of land degradation, which is linked to climate change.
It is important to note that the climate-sensitive sectors (forests, agriculture, coastal zones) and the natural resources (groundwater, soil, biodiversity, etc.) are already under stress due to socio-economic pressures. Climate change is likely to exacerbate the degradation of resources and socio-economic pressures. Thus, countries such as India with a large population dependent on climate-sensitive sectors and low adaptive capacity have to develop and implement adaptation strategies.