The Impact of Predicted Climate Change on Soil Erosion - Term Paper Example

NAME : XXXXXXXXXXXX TUTOR : XXXXXXXXXXXX TITLE : THE IMPACT OF PREDICTED CLIMATE CHANGE ON SOIL EROSION COURSE : XXXXXXXXXXXX INSTITUTION : XXXXXXXXXXXX @2009 Introduction The consensus of atmospheric scientist in various parts of the world is that changes in climatic conditions are taking place, both in terms of air temperature as well as precipitation. Climatic records of the intergovernmental panel of climate change (IPCC) show that the year 1998 can be ranked as the warmest year in the last ten centuries in the Northern Hemisphere. Precipitation records show that there has been a continuous increase in the total precipitation since 1910 to 1996 in the United States of America (IPCC). About half of the increased precipitation percentages were very intense. Soil erosion related studies show that these changes in the climate will negatively bring about increased rates soil erosion and surface runoff in the near future. Figure 1: A Steady increase in temperature between 1860-1980. The rate of soil erosion may be projected to change in response to changes in climate for various reasons. One of the most direct is the change in the erosive power of precipitation. The other dominant alleyway of influence by climate change on the rates of erosion is through changes in the in plant biomass. The means through which the climate changes affect biomass and through which changes have some impact on runoff as well as erosion are very complex. For instance, anthropogenic rise in atmospheric concentration of carbon dioxide lead to an increase in plant production rate together with the changes in the rates of transportation. This eventually translates into a rise in the surface canopy cover, more significantly, the biological ground cover. Increases in soil and air temperature together with moisture lead to faster rates of decomposition of residue as a result of an increase in microbial activity. High rates of precipitation can also contributed to a rise in biomass production. When the temperatures are high, there would be high evaporation rates. More rainfall, on the other hand, would tend to result into high soil moisture levels. An increase in temperature indirectly affects soil erosion in various ways. As the temperatures increases, then there is an increase in the number of days required for a crop to become mature which in turn affects the production rate of the biomass by increasing them. Excessive temperature limit the production of crops since it affects the level of microbial activities this as well affects the rate of residue decomposition.Carbondioxide levels in the air as well has a direct effect on the level of biomass produced by different crops through undeviating carbon dioxide fertilization impacts. This biomass changes impact ground deposits and canopy cover which affects the rates of soil erosion. The increase of carbon dioxide levels boost stomatal resistance, repressing transpiration which leads to the moistening of the soil, fit for great erosion induced by run offs. Temperature increase as well influences the rates of evapo-transpiration which in turn affect the amounts of in filtration and runoffs (Scharpenseel 1990). Research done in west Europe by means of the Erosion Productivity Impact calculator model (EPIC) indicated that a 7% increase in precipitation contributes a 26% escalation in soil erosion This research as well applies and relates to those which were found out in the American corn belt and South Africa. Precipitation in these areas gives a raise in the prevalence of soil erosion and runoff (Munasinghe 1998). The research results as well showed that in areas that had a decline of precipitation levels, levels of soil erosion decreased and increased as well making the production of biomass levels to reduce giving low farm yields (Santer 1985). This adversely affects the farmers causing them to change their course of work. For instance in South Africa there has been a whole range of change of land cover considerably changed the rainfall run off relation from a mix of agricultural and the urban use of land ahs changed. It was also noted in West Europe that there was change in the type of tillage, time of crop planting and plant future might have a great sway on the hydrological responses than the change to a different crop. In West Europe the changes mandated by the government in producing crop to cereal grown in autumn over that duration has brought about the increase of bare land in West Europe which in turn has increased the intensity of soil erosion due to the change of climate and management of crops. Studies carried out in China indicated that about half a century of climatic change decreases water erosion but the use of land has so far changed from grassland to fields of dry crop further compensated for climate adding water erosion and adding to the already felt wind erosion which raises air temperature (Brinkman 1990). The diagrams below show the extent of temperature and rainfall change according to the intergovernmental panel of climate change (IPCC). Figure 2: Change in precipitation for scenario A2 Figure 3: Change in Temperature for Scenario A2 Table representation of Change in temperature and precipitation for scenario A2 Months Temperature change (0C) Precipitation change (mm) January +1.00 +0.3 February +1.00 +0.2 March +1.00 +0.3 April +1.00 +0.2 May +1.00 +0.25 June +1.00 +0.25 July +1.00 +0.25 August +1.00 +0.25 September +1.00 +0.50 October +2.00 +1.00 November +2.00 +1.00 December +2.00 +1.20 Surface runoff, flashfloods and inundation The plant life of natural ecosystem together with rangelands within semi-arid and arid parts of China is a patchwork of clumps of perennial found within a matrix of the soils that lack vegetation and is covered with biogenic crust that reduces the level of permeability of the underlying soil considerably. The predictable reduction in the amount of rainfall, in synergy with the already instigated anthropogenically-induced desertification practices facilitate the crusted areas to expand. In addition to the projected increase in rain intensity, the already expanded biogenic crust will heighten the frequencies as well as the intensities of surface runoff actions, leading erosion of the top soil and loss of water. This further will lead to loss of vegetation, therefore higher frequency and high levels of runoff actions (Day & Templet 1989). An increase in rainfall intensity will facilitate surface runoff in urban areas too. Together with an increase in the surface run-off from open areas, there is likelihood of generation of more frequent as well as powerful floods which not only cause damage to infrastructures and loss of human life but also the loss of water towards the large water bodies (Stigliani 1988). The intensified run-off, together with the rise in the level of the sea and high rainfall intensity may lead to flooding as well as inundation, hence the creation of swamps. A decrease in the hydraulic slop that exists between drainage systems leads to a reduction of the efficiency of the transfer of water hence the possibility of flooding. Inadequate drainage systems within the coastal plains, an area of low altitude as well as high population density may lead to higher vulnerability to projected increases in the intensity of rain and soil erosion in terms of surface runoff (Bowman 1987). Analysis of soil response to the effects of climate change The likely changes in soil-forming factors which directly come about as a result of global change in temperature would be in terms of organic supply from the biomass, the regimes of soil temperature as well as soil hydrology. Soil hydrology features because of the different changes in the rainfall zones together with the probable changes in evapotransiration. There changes in the soil due to the possible increase in sea level as a result of the reduction in Antarctic ice cap as well as the volume and the warming of the ocean. The principal single change in soil is expected as the final result of the assumptions. Changes would be a continuing improvement in the rate of fertility as well as the physical conditions of soils in both humid and sub-humid climates. One other probable change would be poleward withdraw of the permafrost frontier. Various tropical soils that have got low physico-chemical action like in the Amazon regions are likely to undergo fundamental changes from one major soil forming procedure to another (Mintzer 1992). Changes in temperature as well as rainfall to be expected due to global warming may result to increased soil erosions together with other uncertainties for quite a number of reasons. Varied global circulation do not lead to reliable outcomes. (An instance in Europe is noted by Santer, 1985) Oblique results of climate change on soils due to increased levels of CO2 or water use efficiencies, a rise in sea level or change in the activities of man on the soil due to the changes in the various options that are available to the farmer, for instance, may be greater than direct results on soils of higher temperatures or higher rainfall variability. Effects of rainfall and temperature changes in different climates In humid tropics as well as monsoon climate, increased levels of rainfall events and totals would increase the rate of leaching in soils that are well drained and is likely to cause an increased rate of infiltration. This would eventually cause momentary flooding together with the dissemination of water, therefore reducing the level of organic matter putrefaction in a number of soils within depressional sites. This affects a larger proportion of soils, mainly in the Sub-Saharan Africa. It would also trigger greater amount of surface runoff mainly on soils in sloping terrain together with accumulation of sediments down slope and down streams (Brinkman 1987). There would be an increased level of mass movement locally inform of land slides as well as land mudflows in various soft sedimentary materials. The soils that are highly resilient against such changes may have sufficient cation exchange ability and anion sorption to reduce the level of loss of nutrients during leaching flows. There would be a high structural stability together with a sturdily heterogeneous system of constant macrospores to lessen infiltration together with rapid bypass flow through the soil in times of high rainfall intensity (Warrick & Farmer 1990). In the subtropical as well as other sub humid or semi-arid regions, an increase in the level of productivity and the use of water because of higher rates of CO2 may tend to increase ground cover, offsetting the resultant effects of higher temperatures. Incase there would be less amounts of rainfall locally and increased intra and inter-annual variability, these would result into reduced level of the production of less dry matter and therefore, in the course of events leading to lower soil organic matter content. Intermittent leaching in times of high rainfall intensity with less standing vegetation is likely to desalinize some soils in areas that are well drained whereby the ground table is quite high. The soils that are most pliant against the resultant effects of such increasing aridity as well as the variability of rainfall would tend to have higher structural stability as well as sturdily heterogeneous system of continuous macropores, hence an increased rate of infiltration rate and large available water capacity and deep-seated ground table (Brinkman 1985). Higher temperatures, mainly in arid areas, involve high evaporative demand whereby there is adequate soil moisture, for instance in regions that are well irrigated. This could lead to soil salinization in case land or farm water execution or arrangement of irrigation and drainage are not sufficient. Conversely, recent experiments carried out by Salinity Laboratory in California noted the increased soil tolerance of crops found under higher atmospheric CO2 situations. In boreal climates, the steady vanishing of large extents of permafrost as well as the reduction of frost period in widespread belts adjacent to former permafrost are expected to increase the internal drainage of soils in large areas, with possible increases in the rates of leaching. The substantial increase in times when the soil temperatures are higher for the activities of microbial are likely to lead to reduced level of organic matter, possibly not fully remunerated by increased initial productions through fairly higher photosynthesis as well as longer growing periods (Stanley 1988). In contradiction, the extent of soil subject to periodic reduction is likely to increase in areas that are level, despite greater leaching capability due to the increased periods when the soils are highly water-saturated and also efficiently warm for the activities of microbial (Buol & Sanchez 2000). The soils that are most pliant against such form of effects, including the leaching of nutrients and as well as intermittent soil reduction, may have the same characteristics as the most flexible ones in other forms of climates. Efficient exchange of cation as well as onion sorption to reduce the loss of nutrients in times of leaching flows, a high structural constancy and sturdily heterogeneous system of continuous macropores to fully increase a quick circumvent flow during times of excess melt water (Dasgupta & Kiely 2006). Within calcareous soils, the reaction of soil can range between 8.5 and 7, basing on the slight pressure of CO2 in the soil. The range is harmonized against leaching of essential cations through different soil processes provided a given percentage of finely disseminated lime remains. Protection in non-calcareous soils is less strong but highly relies on the cation exchange capability at soil pH. In soils that have change surfaces of clay fraction, there is a decrease with increase in acidification. It is worth noting that the simple modeling of stepped up CaCO3 leaching under a twofold atmospheric CO2 concentration is mainly not true. The leaching of lime is therefore certainly related to the level of decomposition of organic matter, but negatively to the rate of gas diffusion (López 2007). In situation whereby leaching is necessitated by climate change, it would be easy to find soil acidification after a stretched period of time with little apparent change, for instance, in some soils in Europe which have been subjected to acid rain for several decades. The soil might be rapidly depleted of the essential cations. However, a ph change is likely start or may become highly rapid, when certain form o buffering pools are almost exhausted. They are also expected to take place in a variety of ways in quite different times after an increase in temperature as well as changed pattern of rainfall have been operative (Breemen 1990). Conclusions Some major and extensive soil changes that are probable as a result of global climatic change are beneficial, especially the steady increase in the fertility of soil as well as the physical qualities resulting from increased atmospheric CO2. An improvement in the productivity as well as water use efficiency of plants and the generally higher rates of rainfall indicated by a number of global circulation models, and not completely neutralized by higher rates of evapotranspiration would be expected to result into widespread rise in ground cover and hence, improved protection against surface runoff and erosion (Boardman, J 1998). Other probable changes brought about by climate change, that is temperature and precipitation are projected to be comparatively well cushioned by mineral composition, organic matter content or structural solidity of various soils. Nevertheless, a reduction in the cover by vegetation or annual or perennial crops as a result of a decline of precipitation and not compensated by the effect of CO2 may lead to the degradation of the soil structure and reduced level of porosity coupled with increased runoff and erosion on areas that are sloppy and by the concomitant, more widespread and speedy sedimentation various changes to the choices that are available to the land users due to climate change are likely to have the same effects. Bibliography Bowman, W 1987, Relations between CO2 fortification and salinity stress in the C4 non-halophyte, Macmillan, New York. 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