Environmental Systems and Societies Syllabus PDF

Topic 1: Foundations of environmental systems and societies 1.1: Environmental value systems Significant historical influences on the development of the environmental movement have come from literature, the media, major environmental disasters, international agreements and techn...

Topic 1: Foundations of environmental systems and societies 1.1: Environmental value systems Significant historical influences on the development of the environmental movement have come from literature, the media, major environmental disasters, international agreements and technological developments. An EVS is a worldview or paradigm that shapes the way an individual, or group of people, perceives and evaluates environmental issues, influenced by cultural, religious, economic and sociopolitical contexts. An EVS might be considered as a system in the sense that it may be influenced by education, experience, culture and media (inputs), and involves a set of interrelated premises, values and arguments that can generate consistent decisions and evaluations (outputs). There is a spectrum of EVSs, from ecocentric through anthropocentric to technocentric. An ecocentric viewpoint integrates social, spiritual and environmental dimensions into a holistic ideal. It puts ecology and nature as central to humanity and emphasizes a less materialistic approach to life with greater self-sufficiency of societies. An ecocentric viewpoint prioritizes biorights, emphasizes the importance of education and encourages self-restraint in human behavior. An anthropocentric viewpoint argues that humans must sustainably manage the global system. This might be through the use of taxes, environmental regulation and legislation. Debate would be encouraged to reach a consensual, pragmatic approach to solving environmental problems. A technocentric viewpoint argues that technological developments can provide solutions to environmental problems. This is a consequence of a largely optimistic view of the role humans can play in improving the lot of humanity. Scientific research is encouraged in order to form policies and to understand how systems can be controlled, manipulated or changed to solve resource depletion. A pro-growth agenda is deemed necessary for society’s improvement. There are extremes at either end of this spectrum (for example, deep ecologists–ecocentric to cornucopian–technocentric), but in practice, EVSs vary greatly depending on cultures and time periods, and they rarely fit simply or perfectly into any classification. Different EVSs ascribe different intrinsic value to components of the biosphere. A society is an arbitrary group of individuals who share some common characteristics, such as geographical location, cultural background, historical time frame, religious perspective, value system and so on. 1c  Historical influences: ○ James Lovelock’s development of the Gaia hypothesis; ○ Minamata disaster; ○ Rachel Carson’s book Silent Spring (1962); ○ Davis Guggenheim’s documentary An Inconvenient Truth (2006); ○ Chernobyl disaster of 1986; ○ Fukushima Daiihi nuclear disaster of 2011; ○ whaling; ○ Bhopal disaster of 1984; ○ Gulf of Mexico oil spill of 2010; ○ Chipko movement; ○ Rio Earth Summit 2012 (Rio+20); ○ Earth Day; ○ Green Revolution; ○ Copenhagen Accord; ○ Peru oil spill 1.2: Systems and models A systems approach is a way of visualizing a complex set of interactions which may be ecological or societal. These interactions produce the emergent properties of the system. The concept of a system can be applied at a range of scales. A system consists of storages and flows. The flows provide inputs and outputs of energy and matter. The flows are processes that may be either transfers (a change in location) or transformations (a change in the chemical nature, a change in state or a change in energy). In system diagrams, storages are usually represented as rectangular boxes and flows as arrows, with the direction of each arrow indicating the direction of each flow. The size of the boxes and the arrows may be representative of the size/magnitude of the storage or flow. An open system exchanges both energy and matter across its boundary while a closed system exchanges only energy across its boundary. An isolated system is a hypothetical concept in which neither energy nor matter is exchanged across the boundary. Ecosystems are open systems; closed systems only exist experimentally, although the 2c  global geochemical cycles approximate closed systems. A model is a simplified version of reality and can be used to understand how a system works and to predict how it will respond to change. A model inevitably involves some approximation and therefore loss of accuracy. podcast 1.3: Energy and equilibria The first law of thermodynamics is the principle of conservation of energy, which states that energy in an isolated system can be transformed but cannot be created or destroyed. The principle of conservation of energy can be modeled by the energy transformations along food chains and energy production systems. The second law of thermodynamics states that the entropy of a system increases over time. Entropy is a measure of the amount of disorder in a system. An increase in entropy arising from energy transformations reduces the energy available to do work. The second law of thermodynamics explains the inefficiency and decrease in available energy along a food chain and energy generation systems. As an open system, an ecosystem will normally exist in a stable equilibrium, either in a steady-state equilibrium or in one developing over time (for example, succession), and maintained by stabilizing negative feedback loops. Negative feedback loops (stabilizing) occur when the output of a process inhibits or reverses the operation of the same process in such a way as to reduce change—it counteracts deviation. Positive feedback loops (destabilizing) will tend to amplify changes and drive the system towards a tipping point where a new equilibrium is adopted. The resilience of a system, ecological or social, refers to its tendency to avoid such tipping points and maintain stability. Diversity and the size of storages within systems can contribute to their resilience and affect their speed of response to change (time lags). Humans can affect the resilience of systems through reducing these storages and diversity. The delays involved in feedback loops make it difficult to predict tipping points and add to the complexity of modeling systems. A stable equilibrium is the condition of a system in which there is a tendency for it to return to the previous equilibrium following disturbance. 3c  A steady-state equilibrium is the condition of an open system in which there are no changes over the longer term, but in which there may be oscillations in the very short term. A tipping point is the minimum amount of change within a system that will destabilize it, causing it to reach a new equilibrium or stable state. 1.4: Sustainability Sustainability is the use and management of resources that allows full natural replacement of the resources exploited and full recovery of the ecosystems affected by their extraction and use. Natural capital is a term used for natural resources that can produce a sustainable natural income of goods or services. Natural income is the yield obtained from natural resources. Ecosystems may provide life-supporting services such as water replenishment, flood and erosion protection, and goods such as timber, fisheries, and agricultural crops. Factors such as biodiversity, pollution, population or climate may be used quantitatively as environmental indicators of sustainability. These factors can be applied on a range of scales, from local to global. The Millennium Ecosystem Assessment (MA) gave a scientific appraisal of the condition and trends in the world’s ecosystems and the services they provide using environmental indicators, as well as the scientific basis for action to conserve and use them sustainably. EIAs incorporate baseline studies before a development project is undertaken. They assess the environmental, social and economic impacts of the project, predicting and evaluating possible impacts and suggesting mitigation strategies for the project. They are usually followed by an audit and continued monitoring. Each country or region has different guidance on the use of EIAs. EIAs provide decision-makers with information in order to consider the environmental impact of a project. There is not necessarily a requirement to implement an EIA’s proposals, and many socio-economic factors may influence the decisions made. Criticisms of EIAs include: the lack of a standard practice or training for practitioners, the lack of a clear definition of system boundaries and the lack of inclusion of indirect impacts. An ecological footprint (EF) is the area of land and water required to sustainably provide all resources at the rate at which they are being consumed by a given population. If the EF is greater than the area available to the population, this is an indication of unsustainability. 4c 1.5: Humans and pollution Pollution is the addition of a substance or an agent to an environment through human activity, at a rate greater than that at which it can be rendered harmless by the environment, and which has an appreciable effect on the organisms in the environment. Pollutants may be in the form of organic or inorganic substances, light, sound or thermal energy, biological agents or invasive species, and may derive from a wide range of human activities including the combustion of fossil fuels. Pollution may be nonpoint or point source, persistent or biodegradable, acute or chronic. Pollutants may be primary (active on emission) or secondary (arising from primary pollutants undergoing physical or chemical change). Dichlorodiphenyltrichloroethane (DDT) exemplifies a conflict between the utility of a “pollutant” and its effect on the environment. Pollution management strategies at different levels Process of pollution Level of pollution management Human activity Altering human activity producing pollutant The most fundamental level of pollution management is to change the BEFORE human activity that leads to the production of the pollutant in the first place, by promoting alternative technologies, lifestyles and values through: campaigns, education, community groups, government legislation economic incentives/ disincentives Release pollutant Controlling release of pollutant into the environment Where the activity/ production is not completely stopped, strategies can DURING be applied at the level of regulating or preventing the release of pollutants by: legislating and regulating standards of emission developing/ applying technologies for extracting pollutant from emissions Impact of pollutant Clean-up and restoration of damaged systems on ecosystem Where both the above levels of management have failed, strategies 5c  AFTER may be introduced to recover damaged ecosystems by: extracting and removing pollutant from ecosystem replanting/restocking of depleted populations and communities. Topic 2: Ecosystems and ecology 2.1: Species and populations A species is a group of organisms that share common characteristics and that interbreed to produce fertile offspring. A habitat is the environment in which a species normally lives. A niche describes the particular set of abiotic and biotic conditions and resources to which an organism or population responds. The fundamental niche describes the full range of conditions and resources in which a species could survive and reproduce. The realized niche describes the actual conditions and resources in which a species exists due to biotic interactions. The non-living, physical factors that influence the organisms and ecosystem— such as temperature, sunlight, pH, salinity, and precipitation—are termed abiotic factors. The interactions between the organisms—such as predation, herbivory, parasitism, mutualism, disease, and competition—are termed biotic factors. Interactions should be understood in terms of the influences each species has on the population dynamics of others, and upon the carrying capacity of the others’ environment. A population is a group of organisms of the same species living in the same area at the same time, and which are capable of interbreeding. S and J population curves describe a generalized response of populations to a particular set of conditions (abiotic and biotic factors). Limiting factors will slow population growth as it approaches the carrying capacity of the system. 2.2: Communities and ecosystems A community is a group of populations living and interacting with each other in a common habitat. An ecosystem is a community and the physical environment with which it interacts. Respiration and photosynthesis can be described as processes with inputs, outputs and transformations of energy and matter. 6c  Respiration is the conversion of organic matter into carbon dioxide and water in all living organisms, releasing energy. Aerobic respiration can be represented by the following word equation: glucose + oxygen →carbon dioxide + water During respiration, large amounts of energy are dissipated as heat, increasing the entropy in the ecosystem while enabling organisms to maintain relatively low entropy and so high organization. Primary producers in most ecosystems convert light energy into chemical energy in the process of photosynthesis. The photosynthesis reaction is can be represented by the following word equation: carbon dioxide + water → glucose + oxygen Photosynthesis produces the raw material for producing biomass. The trophic level is the position that an organism occupies in a food chain, or the position of a group of organisms in a community that occupy the same position in food chains. Producers (autotrophs) are typically plants or algae that produce their own food using photosynthesis and form the first trophic level in a food chain. Exceptions include chemosynthetic organisms that produce food without sunlight. Feeding relationships involve producers, consumers and decomposers. These can be modeled using food chains, food webs and ecological pyramids. Ecological pyramids include pyramids of numbers, biomass and productivity and are quantitative models that are usually measured for a given area and time. In accordance with the second law of thermodynamics, there is a tendency for numbers and quantities of biomass and energy to decrease along food chains; therefore, the pyramids become narrower towards the apex. Bioaccumulation is the build-up of persistent or non-biodegradable pollutants within an organism or trophic level because they cannot be broken down. Biomagnification is the increase in concentration of persistent or nonbiodegradable pollutants along a food chain. Toxins such as DDT and mercury accumulate along food chains due to the decrease of biomass and energy. Pyramids of numbers can sometimes display different patterns; for example, when individuals at lower trophic levels are relatively large (inverted pyramids). A pyramid of biomass represents the standing stock or storage of each trophic level, measured in units such as grams of biomass per square meter (g m–2) or Joules per square meter (J m-2) (units of biomass or energy). Pyramids of biomass can show greater quantities at higher trophic levels because they represent the biomass present at a fixed point in time, although seasonal variations may be marked. 7c  Pyramids of productivity refer to the flow of energy through a trophic level, indicating the rate at which that stock/storage is being generated. Pyramids of productivity for entire ecosystems over a year always show a decrease along the food chain. Pyramid Units Biomass (standing crop) g m-2 Productivity (flow of biomass/energy) g m-2yr-1 J m-2yr-1 2.3: Flows of energy and matter As solar radiation (insolation) enters the Earth’s atmosphere, some energy becomes unavailable for ecosystems as this energy is absorbed by inorganic matter or reflected back into the atmosphere. Pathways of radiation through the atmosphere involve a loss of radiation through reflection and absorption as shown in figure 4. 8c  Pathways of energy through an ecosystem include: ○ conversion of light energy to chemical energy ○ transfer of chemical energy from one trophic level to another with varying efficiencies ○ overall conversion of ultraviolet and visible light to heat energy by an ecosystem ○ re-radiation of heat energy to the atmosphere. ○ The conversion of energy into biomass for a given period of time is measured as productivity. Net primary productivity (NPP) is calculated by subtracting respiratory losses (R) from gross primary productivity (GPP) NPP = GPP – R Gross secondary productivity (GSP) (assimilation) is the total energy or biomass assimilated by consumers and is calculated by subtracting the mass of fecal loss from the mass of food consumed GSP = food eaten – fecal loss Net secondary productivity (NSP) is calculated by subtracting respiratory losses (R) from GSP. NSP = GSP – R 9c  Maximum sustainable yields are equivalent to the net primary or net secondary productivity of a system. Matter also flows through ecosystems linking them together. This flow of matter involves transfers and transformations. The carbon and nitrogen cycles are used to illustrate this flow of matter using flow diagrams. These cycles contain storages (sometimes referred to as sinks) and flows, which move matter between storages. Storages in the carbon cycle include organisms and forests (both organic), or the atmosphere, soil, fossil fuels and oceans (all inorganic). Flows in the carbon cycle include consumption (feeding), death and decomposition, photosynthesis, respiration, dissolving and fossilization. Storages in the nitrogen cycle include organisms (organic), soil, fossil fuels, atmosphere and water bodies (all inorganic). Flows in the nitrogen cycle include nitrogen fixation by bacteria and lightning, absorption, assimilation, consumption (feeding), excretion, death and decomposition, and denitrification by bacteria in water-logged soils. Human activities such as burning fossil fuels, deforestation, urbanization and agriculture impact energy flows as well as the carbon and nitrogen cycles. 2.4: Biomes, zonation and succession Biomes are collections of ecosystems sharing similar climatic conditions that can be grouped into five major classes: aquatic, forest, grassland, desert and tundra. Each of these classes has characteristic limiting factors, productivity and biodiversity. Insolation, precipitation and temperature are the main factors governing the distribution of biomes. The tricellular model of atmospheric circulation explains the distribution of precipitation and temperature and how they influence structure and relative productivity of different terrestrial biomes. Climate change is altering the distribution of biomes and causing biome shifts. Zonation refers to changes in community along an environmental gradient due to factors such as changes in altitude, latitude, tidal level or distance from shore (coverage by water). Succession is the process of change over time in an ecosystem involving pioneer, intermediate and climax communities. During succession, the patterns of energy flow, gross and net productivity, diversity, and mineral cycling change over time. 10c  Greater habitat diversity leads to greater species and genetic diversity. r- and k-strategist species have reproductive strategies that are better adapted to pioneer and climax communities, respectively. In early stages of succession, gross productivity is low due to the unfavorable initial conditions and low density of producers. The proportion of energy lost through community respiration is relatively low too, so net productivity is high—that is, the system is growing and biomass is accumulating. In later stages of succession, with an increased consumer community, gross productivity may be high in a climax community. However, this is balanced by respiration, so net productivity approaches 0 and the productivity–respiration (P:R) ratio approaches 1. In a complex ecosystem, the variety of nutrient and energy pathways contributes to its stability. There is no one climax community, but rather a set of alternative stable states for a given ecosystem. These depend on the climatic factors, the properties of the local soil and a range of random events that can occur over time. Human activity is one factor that can divert the progression of succession to an alternative stable state by modifying the ecosystem; for example, the use of fire in an ecosystem, the use of agriculture, grazing pressure, or resource use (such as deforestation). This diversion may be more or less permanent depending upon the resilience of the ecosystem. An ecosystem’s capacity to survive change may depend on its diversity and resilience. 11c