Climate change is defined as change in climate over time, whether due to natural variability or as a result of human activity. Adaptive capacity is the ability of a system to adjust to climate change (including climate variability and extremes) to moderate potential damages, to take advantage of opportunities, or to cope with the consequences. Vulnerability is the degree to which a system is susceptible to, and unable to cope with, adverse effects of climate change, including climate variability and extremes. New options for carbon sequestration in agriculture and forestry and land-use change such as deforestation contributes to, respectively, 13 and 17 percent of total anthropogenic greenhouse gas (GHG) emissions. While carbon dioxide emissions from agriculture are small, the sector accounts for about 60 percent of all nitrous oxide (N2O, mainly from fertilizer use) and about 50 percent of methane (CH4, emitted, mainly from natural and cultivated wetlands and enteric fermentation). The IPCC estimates that the global technical mitigation potential for agriculture (excluding forestry) will be between 5 500 and 6 000 Mt CO2-equivalent per year by 2030, 89 percent of which are assumed to be from carbon sequestration in soils.
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Available water
Agriculture of any kind is strongly influenced by the availability of water. Climate change will modify rainfall, evaporation, runoff, and soil moisture storage. Changes in total seasonal precipitation or in its pattern of variability are both important. The occurrence of moisture stress during flowering, pollination, and grain-filling is harmful to most crops and particularly so to corn, soybeans, and wheat. Increased evaporation from the soil and accelerated transpiration in the plants themselves will cause moisture stress; as a result there will be a need to develop crop varieties with greater drought tolerance.
The demand for water for irrigation is projected to rise in a warmer climate, bringing increased competition between agriculture, already the largest consumer of water resources in semiarid regions and urban as well as industrial users. Falling water tables and the resulting increase in the energy needed to pump water will make the practice of irrigation more expensive, particularly when with drier conditions more water will be required per acre. Peak irrigation demands are also predicted to rise due to more severe heat waves.
Conditions are more favorable for the proliferation of insect pests in warmer climates. Longer growing seasons will enable insects such as grasshoppers to complete a greater number of reproductive cycles during the spring, summer, and autumn. Warmer winter temperatures may also allow larvae to winter-over in areas where they are now limited by cold, thus causing greater infestation during the following crop season. Altered wind patterns may change the spread of both wind-borne pests and of the bacteria and fungi that are the agents of crop disease. Crop-pest interactions may shift as the timing of development stages in both hosts and pests is altered. Livestock diseases may be similarly affected. The possible increases in pest infestations may bring about greater use of chemical pesticides to control them, a situation that will require the further development and application of integrated pest management techniques.
Sustainability and food security
Climate change can impact agricultural sustainability in two interrelated ways: first, by diminishing the long-term ability of agro-ecosystems to provide food and fiber for the world's population; and second, by inducing shifts in agricultural regions that may encroach upon natural habitats, at the expense of floral and faunal diversity. Global warming may encourage the expansion of agricultural activities into regions now occupied by natural ecosystems such as forests, particularly at mid- and high-latitudes. Forced encroachments of this sort may thwart the processes of natural selection of climatically-adapted native crops and other species.
While the overall, global impact of climate change on agricultural production may be small, regional vulnerabilities to food deficits may increase, due to problems of distribution and marketing food to specific regions and groups of people. For subsistence farmers, and more so for people who now face a shortage of food, lower yields may result not only in measurable economic losses, but also in malnutrition and even famine. In general, the tropical regions appear to be more vulnerable to climate change than the temperate regions for several reasons. On the biophysical side, temperate C3 crops are likely to be more responsive to increasing levels of CO2. Second, tropical crops are closer to their high temperature optima and experience high temperature stress, despite lower projected amounts of warming. Third, insects and diseases, already much more prevalent in warmer and more humid regions, may become even more widespread.
Inferences:
1. CO2 is increasing.
2. CH4 is increasing.
3. Earth atmosphere systems temperature and Surface temperature
is increasing.
4. Extreme temperatures increasing
5. Atmospheric water vapour content increasing. Frequency of heavy precipitation events increasing
6. More intense and longer droughts.
7. Mid-latitude wind patterns/ storm tracks shifting poleward.
8. Tropical cyclone intensity increasing.
9. Area of seasonally frozen ground decreasing.
10. Glaciers and snow cover decreasing, Arctic sea ice extent decreasing.
- For controlling methane emission from the paddy field, the appropriate water saving technology should be used instead of transplanting and submerged paddy cultivation method.
- Shelter belts should be created near sea shore to check salinity and salt nuclei in atmosphere, which changes rainfall pattern.
- The simulation results indicate that increasing temperature and decreasing solar radiation levels pose a serious threat in decreasing growth and yield of agricultural crops. Increased CO2 levels are expected to favor growth and increase crop yields and therefore, will be helpful in counteracting the adverse effects of temperature rise in future.
• In many studies the impact of climate change on crop growth and yield is analyzed using crop simulation models.
• A proper analysis of the performance of such models should be made to verify their reliability in the projected conditions of changed atmospheric composition and changed climate.
• Further identify regional variations and sensitivity (w.r.t. Climate change)
• Impacts would be analyzed mainly for: Crop yields and variability and
• Shifts in relative productivity and production
Advances in technology has altered the trade off between growth and environmental quality in recent years. It is possible to ensure environmental quality now, more than ever before, if we manage to harness the entrepreneurial skills of the people, administrative skills of the State, the reach of civil society, growth and investments to work for environment rather than against it. Stronger partnerships and better polices can make up for poor resources. The provision of clean drinking water, pure air and sanitation are as much poverty busters as is increase in income.
- Dr. M. C. VARSHNEYA, VC, AAU,
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