Effect of Global Warming on Rice Production in Kebbi State, Nigeria

Transcription

1 Communication International Journal of Marine, Atmospheric & Earth Sciences, 2014, 2(2): International Journal of Marine, Atmospheric & Earth Sciences Journal homepage: ISSN: Florida, USA Effect of Global Warming on Rice Production in Kebbi State, Nigeria B. U. Abdullahi *, J. K. Rai, E. Philemon and N. S. Jega 2 Department of Physics, Kebbi State University of Science and Technology, Aliero, Nigeria Department of Physics, Kebbi State School of Nursing and Midwifery Birnin Kebbi * Author to whom correspondence should be addressed; malabdul01@yahoo.com; Tel.: Article history: Received 21 May 2014, Received in revised form 28 June 2014, Accepted 1 July 2014, Published 9 July Abstract: Rice is one of the major crops, and has a worldwide acceptance as a food crop. Due to the variation of weather and climate from one point to another, the quantity and quality of rice been produced has changed drastically. Effect of global warming on rice production has attracted wide attention all over the world. In this study, effects of temperature, rainfall and relative humidity on rice production were studied. The results showed that all the three factors have significant effects on rice production. Keywords: global warming; rice; production; temperature; rainfall; relative humidity. 1. Introduction Global warming is the rise in the average temperature of earth's atmosphere and oceans since the late 19th century and its projected continuation. Since the early 20th century, earth's mean surface temperature has increased by about 0.8 C (1.4 F), with about two-thirds of the increase occurring since Warming of the climate system is unequivocal, and scientists are more than 90% certain that it is primarily caused by increasing concentrations of greenhouse gases produced by human activities such as the burning of fossil fuels and deforestation. These findings are recognized by the

2 59 national science academies of all major industrialized nations. Climate model projections were summarized in the 2007 Fourth Assessment Report (AR4) by the Intergovernmental Panel on Climate Change (IPCC). They indicated that during the 21st century the global surface temperature is likely to rise a further 1.1 to 2.9 C (2 to 5.2 F) for their lowest emissions scenario and 2.4 to 6.4 C (4.3 to 11.5 F) for their highest. The ranges of these estimates arise from the use of models with differing sensitivity to greenhouse gas concentrations. Future warming and related changes will vary from region to region around the globe. The effects of an increase in global temperature include a rise in sea levels and a change in the amount and pattern of precipitation, as well as a probable expansion of subtropical deserts. Warming is expected to be the strongest in the Arctic and would be associated with the continuing retreat of glaciers, permafrost and sea ice. Other likely effects of the warming include a more frequent occurrence of extreme-weather events including heat waves, droughts and heavy rainfall, ocean acidification and species extinctions due to shifting temperature regimes. Effects significant to humans include the threat to food security from decreasing crop yields and the loss of habitat from inundation. Proposed policy responses to global warming include mitigation by emissions reduction, adaptation to its effects, and possible future geo engineering. Most countries are parties to the United Nations Framework Convention on Climate Change (UNFCCC), whose ultimate objective is to prevent dangerous anthropogenic (i.e., human-induced) climate change. Parties to the UNFCCC have adopted a range of policies designed to reduce greenhouse gas emissions and to assist in adaptation to global warming. Parties to the UNFCCC have agreed that deep cuts in emissions are required, and future global warming should be limited to below 2.0 C (3.6 F) relative to the pre-industrial level. Reports published in 2011 by the United Nations Environmental Program and the International Energy Agency suggest that efforts as of the early 21st century to reduce emissions may be inadequate to meet the UNFCCC's 2 C target. Crop production will be affected by global warming, resulting in world-wide food shortages and starvation. Increased concentrations of carbon dioxide (CO2), one of the main substances responsible for global warming, will promote plant growth through intensified photosynthesis. Some reports indicate that a rise in the levels of CO2 would actually benefit plants, rather than harm them. The growth rates of C3 plants increase in response to elevated concentrations of carbon dioxide (C3 plant are plants that open their stomata during the day to breathe in CO2 and release O2 and more efficient in cool moist condition). Thus, global warming might increase plant growth because of higher temperatures and higher levels of atmospheric CO2. High atmospheric temperatures caused by elevated concentrations of CO2 will induce heat injury and physiological disorders in some crops, which will decrease the incomes of farmers and agricultural countries. Photosynthesis is one of the most sensitive

3 60 physiological processes to high temperature stress. Reproductive development is more sensitive than vegetative development to high temperatures, and heat-sensitivity differs among crops. In tomato, the optimal temperature for fruit set was reported as C (Geisenberg et al., 1986), or C (Peet et al., 1996), while pollen viability and release are adversely affected by high temperatures, and become major limiting factors for fruit set. Thus, global warming can have opposite effects on plant growth. From a long-term viewpoint, however, high atmospheric temperatures will drive the main sites of crop production further north, establishing new rules for the right crop for right land. Water shortages caused by global warming will be the greatest problem for crop production. Plants fundamentally rely on adequate fresh water, and agricultural water accounts for 70% of water use world-wide. As higher temperatures increase evaporation from water sources and decrease precipitation, arid regions will become further decertified. Particularly in semiarid regions, the cultivatable area will decrease because of drought, and this could result in famines and mass migration. As well, it is likely that there will be human conflicts over irrigation water and food. Crop germination and growth rely on optimal temperatures during the period of greatest growth rate. Therefore, non-optimal temperatures slow the growth rate or stop growth altogether. The limiting temperatures for growth are minimum and maximum temperatures, and these vary among crops, crop varieties (Prasad et al., 2006), and among different growth stages in the same crop. In particular, temperature strongly affects crops during their reproductive period, from pollen formation to fertilization. Low or high temperatures during this period can prevent crop fertilization and cause seed abortion. To achieve high yields, crops must be protected from pests, diseases, and weeds. Of the total cropping area worldwide, crop yield is decreased by 10 20% by weeds (Kaiser et al., 1993). Many C4 weeds are found in arable C3 crops and many C3 weeds in arable C4 crops. Therefore, under high temperatures and increased atmospheric CO2 concentrations, weed damage to arable C4 crops in tropical and subtropical semiarid areas is predicted to increase. It is likely that global warming will result in pests and diseases that are currently found in low-latitude regions spreading to high-latitude regions. Bacteria and fungi are the main causal agents of plant diseases, and their optimal growth temperatures are approximately 25 C and above 30 C, respectively. Temperature also affects the growth of insects, with higher temperatures increasing their growth rate. Therefore, continued warming is expected to increase damage to crops from bacteria, fungi, and insects. As global warming progress, there will be increased evaporation from the earth s surface and from plants. Even a 1 C temperature increase would increase the amount of evaporation from the earth. As well, increased temperatures result in more concentrated, heavy rainfall, and crops show decreased rainfall use efficiency in such circumstances. Snowfall, which results in stored water

4 61 resources, also decreases with higher temperatures, and snow melts more rapidly. Together, these factors could combine to increase drought in the major agricultural regions the mid-latitude continents. This could significantly restrict the world s food supply. Desertification of dry areas is very likely to result from global warming. In dry areas, water moves from subsurface to surface layers of the soil. Therefore, when capillary water reaches the ground or irrigation water evaporates, the soluble salts that dissolved into the water in the lower layers are concentrated in the surface soil layer. As a result, salt accumulates at the surface where it negatively affects or prevents plant growth. In dry regions, more water will evaporate as temperatures increase, turning these areas into deserts (Doorenbus et al., 1977). Desertification decreases the amount of vegetation, reducing CO2 absorption by plants, and further progressing global warming. The area of the world s deserts is expanding by 60,000 km 2 each year, and the desertification of humid and semi-arid areas and the dry sub-humid areas used to cultivate wheat and other grains could cause a serious food crisis. Strong tropical storms, hurricanes, typhoons, and cyclones severely damage farmland (Euroconsult et al., 1989). In this study, effects of global warming with particular emphasis to temperature, rainfall and relative humidity on rice production were studied. 2. Materials and Methods 2.1. Materials The materials used for the study include temperature, relative humidity and rainfall data, all for the years The rice yield for the years Then Microsoft office 2007 is utilized for analysis Methods Graphical method is a mathematical representation of data s which include diagram techniques, chart techniques for plotting of graphs made of different dimensions, and other forms of visualization. 3. Results and Discussion After subjecting the various data to Microsoft excel, the following graphs shown in Fig. 1-3 represent the results obtained Rice Production in the Year 2008 In the year 2008, the data clearly showed that there was no rainfall in the months of January, February and December. The lowest temperature for the year 2008 was 24.3 o C and the highest was

5 o C. The relative humidity ranges from the minimum of 18% in the month of February to the maximum of 86% in the month of August. The rainfall started in the month of March and gradually gets to its peak in the month of September recording the highest rainfall of the year 2008, in the graph above as the rainfall increases to mm. The level of rice production increases to 6.84% recording the highest production of the year. The level relative humidity is kept high but not at its peak and so temperature of the surrounding is fairly kept in the average. So, as the rainfall decreased in the end of November 2008, we observed that the production of rice slightly decreased. Figure 1. Graph of rice production for year Rice Production in the Year 2009 In the year 2009 we also noticed that in the months of January, February, November and December there were no rainfall on the speculated area of cultivation, in the month of March 2009 the first rain was experienced as the month grow older stepping to the next month we observe increase in the production on rice, specifically in the month of August rice production improve drastically recording the highest production in August at the peak of 21% realizing heavier rainfall of mm, the temperature for the year 2009 increase and decrease at the period of rainfall in that year by small margins, but in the period of high production the temperature of the surrounding is kept at fairly cool proportion. The relative humidity at the point of high production is 84% which is relatively high also. The production of rice in the year 2009 has a better yield.

6 63 Figure 2. Graph of rice production for year Rice Production in the Year 2010 In the year 2010 less rainfall was recorded, and in that year in Kebbi metropolis there was no rain in the months of January, February, March, November and December, rain fell only for the period of 6 to 7 month but record a nice production. The highest production of rice was recorded in the month of August with rainfall of 355 mm and production of 24.3% which is a bit good, and the rainfall decrease towards September and October season, temperature recorded at the highest production level is 27.3 o C which is fairly cool and almost kept below the average. The relative humidity increased as the rate of production of rice increased with increase in rainfall it reached its peak of 83 mm and decreased as the rainfall decreases throughout the year Figure 3. Graph of rice production for year 2010.

7 64 4. Conclusions From the recorded data, it was observed that rice is affected by temperature, relative humidity and rainfall, but in the context above it shows that rainfall has a greater impact in the production and yield of the rice used as a case study, temperature and relative humidity also contribute in the effect to the rice. We study the interrelationship between the effect of global warming on crop production and the variance between their effects on rice. Global warming with its attendant effects ranging from drought, desertification, change in rainfall pattern increase on average temperature etc has really affected agricultural yield as it can be seen from the yield results for There is a high risk that a hotter, drier climate will negatively affect crop production. A moderate increase in the global average temperature (1-3 o C) could increase food production, but additional temperature increases would cause an overall decline in food production. In low-latitude regions, especially seasonally dry semitropical areas, temperature increases of only 1 or 2 o C are likely to negatively affect rice yield because of drought, although the effect of global warming on food production will vary among regions and crop types. References Doorenbus, J., and Pruitt, W. O. (1977). Guide Lines for Predicting Crop Water Requirements. Irrigation and Drainage paper, FAO, Vol. 24, pp Euroconsult. (1989). Agricultural Compendium for Rural Development in the Tropics and Subtropics. Elsevier, Vol. 13, p. 1. Geisengerg, H. D., and Stewart, G. F. (1986). Crop Science, Oxford, Vol. 11: p. 4. Kaiser, H. M., Riha, S. J., Wilks, D. S., Rossier, D. G., and Sampath, R. (1993). A farm-level analysis of economic and agronomic impacts of gradual warming. Amer. J. Agric. Econ., 75: Peet, G. H., and Batholemew, D. F. (1996). Effect of Temperature on Crops. Batholemew Publisher, Vol. 1, pp Prasad, N. J. (2006). Effect of Soil Temperature on Seed Growth. Mechanical Engineering Publisher, Vol. 3, p. 168.