Impact of Climate Change on Agriculture
Agriculture sector alone contributes 23% of India’s GNP and play crucial role in the economy of the country. It sustains 70% of the India’s population. The Economic impact due to climate change is on the agriculture profitability, prices, supply, demand, trade etc. Agriculture is one of the vulnerable sector influenced by the climate change particularly the crop production, yield and Food Security over the Globe. Climate Change also affected the different growth stages of the crop like sowing, vegetative growth, flowering, fruiting or grain formation as well as during Physiological maturity due to rise in atmospheric temperature, skewed rainfall distribution, soil moisture depletion etc. The main culprits of Climate Change are the Green House Gases, (GHG), like CO2, N2O, Methane and ChloroFlouro Carbons (CFCs).The mean temperature in India projected to increase by 0.10 C to 0.30C in Kharif season and 1.10C to 4.50C in Rabi season by 2010. By 2070, the increase will be 0.40C to 2.00C during Kharif and 1.10C to 4.40C in Rabi season which may result in extreme droughts or floods.
Carbon Di Oxide(CO2)
CO2 emission has very much increased due to increased urbanization and deforestation. Recently Agricultural crop burning, stubble burning increased the CO2 amount considerably. CO2 also get emitted in the atmosphere by the fossil fuel burning during agricultural production and live-stock production. High intensity animal production is the major consumer of Fossil Fuel. In nature Volcanic Eruptions also cause huge temperature rise. The average residual time of CO2 in the atmosphere is about 120 years with increase of 1.8 ppm per year reaching a maximum of 605 ppm to 756 ppm by 2050. By 2070 CO2 along with GHG is likely to increase considerably the temperature of the environment. In India CO2 fixation is important, because we use about 190 million hectares of farming and the estimated biomass production from the Agriculture is about 800 million tons every year.
Methane (CH4)
Methane is another GHG (Green House Gas) responsible for Climate Change and Global Warming. Again agriculture sector is mainly responsible for the rise of Global temperature It is estimated that Paddy fields contribute annually about 90% of Methane emission followed by Animal Husbandry(8%) and Stubble Burning(2%). At the same time emission of Methane gas depends on the soil type, soil heat, Agricultural Practices etc. The Alkaline Soils found to emit more Methane than Acidic Soils. Buffalos and other Cattle contribute 80% of Global Methane annually. The average residual life time is about 11 years.
Nitrous Oxide (N2O)
The main source of Nitrous Oxide, N2O is from the Nitrogen Fertilizers used in Agriculture. The crops absorb most of the N2O gas but the rest gets leached out to the surroundings and diffuse to the atmosphere. It is estimated that on an average Rice crop uses about 33% of the Nitrogen in the fertilizer and rest is denitrified and diffuses as N2O in the air. The Residual period of this gas in the atmosphere is 160 years. This gas is more lethal (300 times) than CO2. Over and above Nylon and Foam industries contribute a lot of N2O with 0.22% increase in the atmosphere. N2O is also partly responsible for the destruction of Ozone in the Stratosphere.
ChloroFlouro Carbons(CFCs)
CFCs contain Halogen atoms like Chlorine, Bromine etc. detected by Ultra Violet radiation. These deplete Ozone in the Stratosphere to thin its layer called “The Ozone Hole”. Most CFCs are man-made like refrigerants, perfumes, deodorants, etc. The CFCs too cause to rise of Global Temperature and their life periods vary from 55 years to 500 years in the atmosphere.
Skewed Rainfall Distribution
In India rain fed agriculture contribute 44% of the total grain production. Selected Locations in the Central and Southern regions of India indicate a shift in the rainfall pattern, particularly in the latter phase of the South West Monsoon. This trend due to climate Change has profound influence on the normal crop growth cycle. Now the farmers are shifting their cropping pattern to match the modified and skewed rainfall distribution. A similar trend is seen in the decrease of rainfall distribution during the pre-monsoon rainfall season in Central Region of India during May-June months which may harm the Rice crops already sown. The erratic rainfall distribution in Semi Arid and Arid regions of India has resulted in the depletion of the soil moisture leading to soil and crop droughts.
Negative aspects of Climate Change
There is a geographical shift in agricultural yield of crops due to Climate Change. There is an increase of temperature, dry soil moisture and skewed rainfall makes less water availability for crops. Also globally, the sea surface temperature is rising, ice caps melting and hence sea level also rising., causing submergence of coastal agricultural lands with floods. In India, some of the fruit cultivation like Apple getting shifted to higher altitude and latitude due to Climate Change. It is estimated that an increase of 10C and increase of CO2 emission results in the reduction of Wheat grain yield by 4 to 5 million tonnes annually. High temperature also affects the fertility of pollen grains as well as their germination. It is estimated that an increase of 10C to 40C in temperature of the atmosphere reduces rice grain yield by 5% to 49% annually in various regions. Similarly Potato Crop yield gets reduced between 40% to 55% and Soya Bean 11% to 36% annually. Similarly the Insect Pest population is also very much affected due to exposure of extreme temperatures to Insect populations and its growth cycle may adversely affect their population. Hence Crop-Insect-Pest relations should be studied in deep and evaluated with respect to Climate Change and Global Warming in order to asses crop losses. However, what all we need is to focus on the different water and nutrient management options, proper evaluation of sequestration potential of land, effective methods to reduce CH4 emission, focus on Nitrogen Fertilizer efficiency etc. in order to face the challenges of Climate Change impact on the Agriculture.
K. K. Nathan
Principal Scientist (Retd.), IARI, New Delhi
