Env 101: Introduction to Environmental Science Lecture 1 PDF

ENV 101: Introduction to Environmental Science Ms Karishma Sinha LECTURE 1  Basic Themes The branch of biology concerned with the relations between organisms and their environment Environmental science is a group of sciences that attempt to explain how life on the...

ENV 101: Introduction to Environmental Science Ms Karishma Sinha LECTURE 1  Basic Themes The branch of biology concerned with the relations between organisms and their environment Environmental science is a group of sciences that attempt to explain how life on the Earth is sustained, what leads to environmental problems, and how these problems can be solved  Human population growth (the environmental problem). Sustainability (the environmental goal). A global perspective (many environmental problems re- quire a global solution). An urbanizing world (most of us live and work in urban areas). People and nature (we share a common history with nature). Science and values (science provides solutions; which ones we choose are in part value judgments).  Environmental science is multidisciplinary in nature and involves the study of biology, physics, chemistry, geology and ecology. Knowledge of political science as well as economics is often required  Sustainability Sustainable Resource Harvest: Sustainable supply of timber. Same resource may be harvested each year for an unlimited or specified length of time without decreasing the ability of that resource to continue to produce that same harvest level. Ex: Shegun tree harvest in one acre of land Sustainable Ecosystem: An ecosystem that is still able to maintain its essential functions and properties even though human beings are harvesting one of its resources. Sustainable Development: A society can continue to develop its economy and social institutions and also maintain its environment for an indefinite time  Carrying Capacity Tied in with SUSTAINABILITY Maximum number of individuals of a species that can be sustained by an environment without decreasing the capacity of the environment to sustain that same amount in the future  Urban World Tied in with ECONOMIC DEVELOPMENT Cities Develop Where? ( Major Rivers) Cities in Developed (75 %) vs Developing countries (45%) Dhaka-The Mega City  People & Nature Environmental problems are the result of human actions and the solution is simply to stop these actions-people are separate from nature Scientific analyses of the environment controversy leading to cooperative problem solving Our relationship with nature and how we ‘change’ nature-service functions Becoming more ‘earth centered’ and applying sustainability to economy  Science & Values Choosing what we want the environment to be requires scientific data and knowledge in order to know what is possible Critical thinking that is disciplined using intellectual standards, effective communication, clarity and commitment to developing scientific knowledge Leading to conclusions, generalizations, scientific theories and laws  In 1992 the Rio Earth Summit on Sustainable Development listed as one of its principles what we now call the Precautionary Principle. Basically, it says that when there is a threat of serious, perhaps even irreversible, environmental damage, we should not wait for scientific proof before taking precautionary steps to prevent potential harm to the environment.  Critical thinking about: Manufacture and use of chemicals (pesticides, herbicides and drugs) Use of fossil fuels and nuclear energy Land conversion Management of wildlife, fisheries and forests  Extent of scientific evidence required before action is taken Need to evaluate all scientific evidence New tool for environmental management Thinking ahead and predicting potential consequences before they ocur  Pollution-Based on Sources Pollution: Is the harm that results because of the presence of a substance or substances where they would not normally be found or because they are present in larger than normal quantities. Polluting substances may occur as a solid, liquid or gas. Point source pollution: Enters the environment at a specific site and is generally readily identified. Potential point sources of pollution include effluent discharges from sewage treatment works and industrial sites, power stations, landfill sites, fish farms, and oil spillage via a pipeline from industrial sites. Point source pollution is generally readily prevented since it is possible to identify where it is coming from and, having done so, those responsible for causing the pollution can take preventative measures through immediate remedial action or longer-term investment in treatment and control facilities.  Diffuse pollution: Arises where substances are widely used and dispersed over an area as a result of land-use activities such as urban development, amenity, farming and forestry. These activities may be recent or have been carried out in the past. It is often difficult to identify specific sources of such pollution and therefore take immediate action to prevent it, since prevention often requires major changes to land use and management practices. Examples include the leaching to surface water and groundwater of contaminants from roads, manures, nutrients and pesticides used in agriculture and forestry, and atmospheric deposition of contaminants arising from industry. A special case arises where, for example, a power station may emit sulphur dioxide and nitrous oxide to the air. Although this is a point source, the deposition (fallout) and, hence, impact will be over a wide area as diffuse pollution.  Environmental Resources May also be called “Natural resources” Defined as resources occurring naturally in nature that may be used to create wealth Examples include: Land, Water, Oil, Coal May be divided into: Biotic Sources: Resources obtained from the biosphere, such as forests and their products, animals, birds and their products, fish and other marine organisms. Mineral fuels such as coal and petroleum are also included in this category because they are formed from decayed organic matter.  Abiotic Sources: Resources include non-living things. Examples include land, water, air and ores such as gold, iron, copper, silver etc Renewable Resources: Can be replenished or reproduced easily. Some of them, like sunlight, air, wind, etc., are continuously available and their quantity is not affected by human consumption. Many renewable resources can be depleted by human use, but may also be replenished, thus maintaining a flow. Some of these, like agricultural crops, take a short time for renewal; others, like water, take a comparatively longer time, while still others, like forests, take even longer  Non-renewable Resources: Are formed over very long geological periods. Minerals and fossil fuels are included in this category. Since their rate of formation is extremely slow, they cannot be replenished once they get depleted. Of these, the metallic minerals can be re-used by recycling them. But coal and petroleum cannot be recycled On the basis of availability environmental resources may be also categorized into exhaustible and inexhaustible natural resources  Population Dynamics Population doubled in the last 40 years Now at 7 billion Current rate of growth may result in 9 billion by 2040 Earth has limited space as well as resources, estimates of supporting capacity ranges from 2.5 billion to 40 billion, varying widely based on acceptable quality of life This in turn depends on people and nature, science and values as well as distribution of population on earth Interaction between population growth/fluctuation rates & the natural/man-made environment  Modern technology and modern medicine has extended people lives, reducing death rates and increasing birth rates due to better access to resources such as food, clothing and shelter Resulting in a population explosion, most dramatically so in the last part of the 20th century, doubling in a matter of only 40 years This poses a tremendous threat to the environment often resulting in disasters such as plagues and famines, all examples of how people affect nature and nature affects people  Population Dynamics Population dynamics-general study of population changes Population Species Demography-statistical study of human population Five key properties of any population: abundance, birth rates, death rates and age structure Logistic growth curve, logistic carrying capacity and inflection point  It took all of human history up to the early 1800s for world population to reach 1 billion people, and until 1960 to reach 3 billion. Today, the world gains 1 billion people every 11 years  Age structure The age structure of a population affects current and future birth rates, death rates, and growth rates; has an impact on the environment; and has implications for current and future social and economic conditions.  The Human population effect on earth Achieving zero population growth via various approaches: - Age of first childbearing - Birth control - National Programs