How will agriculture adapt to climatic change? - I
Global warming is one of the several crucial challenges that already impede the progress of agriculture, particularly in the vast marginal rain fed farming regions. A new model of development is required to give urgency to cope with climate change.
GLOBAL WARMING is a modern development problem involving the entire world tangled up with difficult issues such as poverty, economic development and population growth. Dealing with it will not be easy. Ignoring it will be worse. This is one of the several crucial challenges that already impede the progress of agriculture, particularly in the vast marginal rain fed farming regions, where majority of the earth’s poor and food insecure reside. This means that addressing the difficulties that farmers already faced in many areas - not only low and erratic rainfall and hot temperature, but also inadequate infrastructure, lack of access to markets and credit and other challenges, will contribute to the current agricultural development and food security while building resilience to future climate change.Use of bio-technology for development of varieties with enhanced tolerance to biotic and abiotic stress, resource conservation technologies that use less water and nutrients are some examples of technologies required to tackle the effect of climate change.A new model of development is required to give urgency to coping with climate change. Apparently, successful adaptation will require not only new crop technologies and increased investment in water security, but also policy backup to give small-scale subsistence farmers better access to information, credit and market. Understanding these impacts will help clarify the specific adaptation that both policy makers and farmers must make.
We are living in the midst of constantly changing climatic conditions, largely a result of human interference and if allowed to continue it can cause irreparable damage to flora, fauna and human life. The rise in the average temperature near the earth’s surface, by the use of fossil fuels such as coal, industrial and agricultural processes is scientifically termed as global warming. This is like when the heat is trapped in the car. On a very hot day, the car gets hotter when it is out in the parking lot. This is because the heat and light from the sun can get into the car through the windows, but it cannot get back out of it. This is what the green house effect does to the earth. The heat and light can get through the atmosphere, but it cannot get out. As a result the temperature rises. Warming tends to change climatic patterns across the globe resulting in the complicated problem of global climate change. Global climate change as the term suggests is a global issue and is not restricted to the activities of particular individual, community, zone, region, state or country. Global warming is the increase in the average measured temperature of the earth's near-surface air and oceans since the mid-twentieth century and its projected continuation. The average global air temperature near the earth's surface increased 0.74 ± 0.18°C (1.33 ± 0.32°F) during the hundred years ending in 2005. The earth's climate changes in response to external forcing, including variations in its orbit around the sun (orbital forcing), changes in solar luminosity, volcanic eruptions and atmospheric greenhouse gases(GHGs) concentrations.
The detailed causes of the recent warming remain an active field of research, but the scientific consensus is that the increase in atmospheric GHGs due to human activity caused most of the warming observed since the start of the industrial era. The global increases in carbon dioxide (CO2) concentration are due to fossil fuel use and land-use change, while those of methane (CH4) and nitrous oxide (N2O) are primarily due to agriculture. This attribution is clear for the most recent 50 years, for which the most detailed data are available. Paleoclimate information supports the interpretation that the warmth of the last half century is unusual in at least the previous 1300 years. The last time the polar regions were significantly warmer than present for an extended period was about 125,000 years ago; reductions in polar ice volume led to four to six meters of sea level rise. Some other hypotheses departing from the consensus view have been suggested to explain most of the temperature increase. One such hypothesis proposes that warming may be the result of variations in solar activity. None of the effects of forcing are instantaneous. The thermal inertia of the earth's oceans and slow responses of other indirect effects mean that the earth's current climate is not in equilibrium with the forcing imposed. Climate commitment studies indicate that even if GHGs were stabilised at 2000 levels, a further warming of about 0.5°C (0.9°F) would still occur.
Climatic change and the associated global warming are underway. It occupies the centre stage at all levels as its impact is likely to have serious consequences for the humanity and environment. Sine 1990, the global mean temperature has increased by 0.70 Celsius. Eleven out of 12 warmest years are recorded during the period between 1995 and 2006, and it is expected that the temperature would rise by 0.740C by 2100. Intergovernmental Panel on Climate Change (IPCC) has concluded that human activities that emit GHGs into atmosphere are responsible for most of the warming of at least past 50 years.
Past emissions that are already in the pipeline mean that even if global emissions stop today, the earth’s temperature would rise by about 0.5 to 10 Celsius over the next several decades. Even if global emission is stabilised today, the temperature would increase by 2 to 50 Celsius by the time it reaches equilibrium. And if emissions continue to grow at current rates, they would cause temperatures to rise by 3 to 100 Celsius, not including climatic feedback effects that could further exacerbate climatic change in a vicious circle. Climatic change is rapidly emerging as one of the most serious threats that humanity may ever face. Because it is linked so closely to natural resources and climatic conditions that agriculture will keenly feel the effect of climatic change through changes in both the temperature and precipitation and thus the availability of water for growing food. It is predicted that the interiors of major continents will become warmer more quickly than the oceans. In addition current weather extremes are likely to be exacerbated. It is likely that wet areas of the world will get even wetter and dry areas will get drier. Agriculture is the largest consumer of water globally and as climatic change alters the quantity and reliability of water supplies, it could threaten the welfare of millions of poor farmers.
The effect, however, depends on the latitude; in temperate countries effects are found less negative or even rather beneficial, while in tropical and desert countries they tend to be adverse. Finally, the effect depends on altitude, mid and high altitude places benefiting more rather by a warmer temperature. The weather conditions, that is, temperature, radiation and water, determine the carrying capacity of the biosphere to produce enough food for human population and domesticated animals. Any short term fluctuations of the climate can have dramatic effects on agricultural productivity. Increased CO2 concentration will increase branching leaf area of the crops that will also reduce soil moisture. However, the more favourable effects on yield depend to a large extent on realisation of the potentially benefiting effects of CO2 on crop growth and increase of efficiency of water use. Decrease in potential yields is likely to be caused by shortening of the growing period, decrease in water availability and poor vernalisation. Further, weeds would undergo the same acceleration of cycle as cultivated crops and would also benefit from carbonaceous fertilisation. Most weeds being C3 plants, they are likely to compete even more than now. There will be considerable effect on microbes, pathogens and insect population and virulence.
Agricultural production in many countries including India would be severely compromised by climatic variability. Greater loss is expected in Rabi as compared to Kharif crops. By 2020, in some African and Asian countries, yield from rain fed agriculture could be reduced by up to 50 per cent. Agricultural production, including access to food in many African and Asian countries is projected to be severely compromised. Agriculture and allied activities constitute the single largest component of India’s gross domestic product, contributing nearly 25 per cent of the total. Tremendous importance of this sector to the Indian economy can be gauged by the fact that it provides employment to two-thirds of the total workforce. Indian climate is dominated by the south-west monsoon, which brings most of the region’s precipitation. It is critical for the availability of drinking water and irrigation for agriculture. Agricultural productivity is sensitive to two broad classes of climate-induced effects—(1) direct effects from changes in temperature, precipitation, or carbon dioxide concentrations and (2) indirect effects through changes in soil moisture and the distribution and frequency of infestation by pests and diseases. Rice and wheat yields could decline considerably with climatic changes (IPCC 1996; 2001). However, the vulnerability of agricultural production to climate change depends not only on the physiological response of the affected plant, but also on the ability of the affected socio-economic systems of production to cope with changes in yield, as well as with changes in the frequency of droughts or floods. The adaptability of farmers in India is severely restricted by the heavy reliance on natural factors and the lack of complementary inputs and institutional support systems.
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