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Nigeria's free digital learning hub. Videos, lecture notes, practice questions and leaderboards aligned with CCMAS, NBTE, NCCE, WAEC, NECO, IJMB and JAMB curricula.
Environmental Health Science · 300 Level
This is the complete lecture note for EVM 314 Principles of low carbon society, prepared for Environmental Health Science students at 300 Level. You can read it online below, open it in the full viewer, or download the PDF for offline study. It pairs with the course's video lectures, so you can read and watch together.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Series 1 Course code: EVM 314 Course title: Principles of Low Carbon Society Course credit load: 2 Units List of Series: Series 1: Science and Debates on Carbon Emission Series 2: Carbon Emission and Global Warming Series 3: Approaches to Achieving a Low Carbon Society Series 4: Strategies for Establishing Carbon Sinks Series 5: Methods for Reducing Emissions and Enhancing Sinks Series Outline for Series 1: Science and Debates on Carbon Emission Part 1 (1.1): The Science of Carbon Emission o Sub-Part 1.1.1: What is carbon and where does emission come from? o Sub-Part 1.1.2: The carbon cycle and the carbon budget Part 2 (1.2): Greenhouse Gases and Atmospheric Accumulation o Sub-Part 1.2.1: Carbon dioxide, methane, and other greenhouse gases o Sub-Part 1.2.2: How GHGs accumulate in the atmosphere Part 3 (1.3): Carbon Sinks and the Role of Vegetation o Sub-Part 1.3.1: Forests and vegetation as carbon sinks o Sub-Part 1.3.2: Deforestation and the reduction of carbon sinks Part 4 (1.4): Debates and Diverse Views on Carbon Emission o Sub-Part 1.4.1: The scientific consensus on carbon emission o Sub-Part 1.4.2: Socioeconomic and political debates on carbon emission
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Introduction Carbon emission sits at the heart of one of the most pressing environmental challenges of our time. You will encounter the term frequently in scientific reports, government policies, and public debates, yet its meaning, causes, and consequences are often poorly understood. In this Series, we build the foundation you need: an understanding of what carbon emission is, how it drives the accumulation of greenhouse gases in the atmosphere, why the loss of vegetation makes the problem worse, and what diverse voices across science, economics, and politics say about it. The aim of this Series is to introduce you to the science of carbon emission, explain how greenhouse gases accumulate in the atmosphere and contribute to global warming, examine the role of vegetation as a carbon sink and how its removal intensifies accumulation, and explore the diverse scientific and socioeconomic debates surrounding carbon emission. We shall begin in Part 1 by examining the science of carbon emission: what carbon is, where emissions come from, and how the carbon cycle operates. In Part 2, we will study the main greenhouse gases, particularly carbon dioxide and methane, and explain how they accumulate in the atmosphere. In Part 3, we will explore how forests and other vegetation act as carbon sinks, and examine how deforestation reduces this sink capacity and enhances GHG accumulation. Finally, in Part 4, we will consider the scientific consensus on carbon emission alongside the socioeconomic and political debates that shape responses to it. Series Learning Outcomes Upon completing this Series, you should be able to: SLO 1.1 explain the science of carbon emission, identifying its main sources and the operation of the carbon cycle, SLO 1.2 describe the principal greenhouse gases and explain how they accumulate in the atmosphere, SLO 1.3 analyse the role of forests and vegetation as carbon sinks and the effect of deforestation on GHG accumulation,
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS SLO 1.4 identify the key positions in the scientific consensus on carbon emission, and SLO 1.5 evaluate the socioeconomic and political debates that shape responses to carbon emission. 1.1 The Science of Carbon Emission 1.1.1 What is carbon and where does emission come from? Carbon is the chemical element at the centre of all life on Earth. In the context of climate science, we are most concerned with carbon in its gaseous forms, especially carbon dioxide (CO₂) and methane (CH₄), because these gases are released into the atmosphere when carbon-rich fuels and materials are burned or decomposed. Carbon emission refers to the release of these carbon-containing gases into the atmosphere through human activities and natural processes. The major human sources of carbon emission include the burning of fossil fuels such as coal, oil, and natural gas for energy; deforestation, where trees that stored carbon are cut and burned; industrial processes such as cement production; and agricultural activities including livestock rearing and rice cultivation. Natural sources include volcanic activity, the decomposition of organic matter, and respiration by living organisms. In Nigeria, you can see direct examples of carbon emission in gas flaring in the Niger Delta, forest clearance for agriculture, and the use of generators and charcoal for domestic energy. Fill in the blank: The release of carbon-containing gases into the atmosphere through human activities and natural processes is referred to as carbon __________. 1.1.2 The carbon cycle and the carbon budget The carbon cycle is the natural process by which carbon moves continuously between the atmosphere, living organisms, soils, oceans, and geological deposits. You can think of it as a set of flows: plants absorb CO₂ from the air during photosynthesis and convert it into organic matter; animals eat plants and release CO₂ through respiration; dead organisms decompose and return carbon to the soil; and the oceans dissolve large quantities of CO₂ from the atmosphere. Under natural conditions, these flows are roughly in balance. A carbon budget describes the balance between carbon entering and leaving the atmosphere. When human activities release more carbon than natural sinks can absorb, the budget moves into deficit:
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS atmospheric CO₂ rises. Since pre-industrial times, atmospheric CO₂ has increased from about 280 parts per million to over 420 parts per million today, driven overwhelmingly by fossil fuel combustion and deforestation. This imbalance in the carbon budget is the root cause of the enhanced greenhouse effect that drives global warming. Fill in the blank: The natural process by which carbon moves continuously between the atmosphere, living organisms, soils, oceans, and geological deposits is called the carbon __________. Short description: A labelled diagram of the carbon cycle showing the main reservoirs (atmosphere, land, ocean, geological deposits) and the key fluxes (photosynthesis, respiration, decomposition, fossil fuel combustion, ocean uptake). Plate 1.1 The carbon cycle: flows of carbon between the atmosphere, biosphere, oceans, and geological deposits Pilot questions 1.1 1. What is meant by carbon emission? 2. Name two major human sources of carbon emission.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS 3. What is the carbon cycle? 4. What is a carbon budget, and what happens when it moves into deficit? 5. By how much has atmospheric CO₂ increased since pre-industrial times, and what has driven this increase? 1.2 Greenhouse Gases and Atmospheric Accumulation 1.2.1 Carbon dioxide, methane, and other greenhouse gases When carbon is released into the atmosphere, it does not exist alone. It joins a group of gases collectively known as greenhouse gases (GHGs) because, like the glass of a greenhouse, they trap heat from the sun and warm the Earth's surface. The most important GHG produced by human activity is carbon dioxide (CO₂), which is released by burning fossil fuels, deforestation, and cement production. The second most significant is methane (CH₄), which is emitted from livestock digestion, rice paddies, landfills, and leaking gas pipelines. Methane is about 80 times more potent than CO₂ over a 20-year period, though it breaks down faster in the atmosphere. Other important GHGs include nitrous oxide (N₂O) from agricultural soils and fluorinated gases from industrial processes. Carbon emission is considered the greatest single contributor to GHG accumulation because CO₂ persists in the atmosphere for hundreds of years and is produced in far greater volumes than any other human-made GHG. Fill in the blank: Gases that trap heat in the atmosphere and warm the Earth's surface are collectively known as __________ gases.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Short description: A comparative bar chart or infographic showing the global warming potentials and main sources of the four principal greenhouse gases: CO₂, CH₄, N₂O, and fluorinated gases. Plate 1.2 The principal greenhouse gases: sources and relative warming potentials 1.2.2 How GHGs accumulate in the atmosphere You may wonder how releasing gases into such a vast atmosphere can cause a problem. The answer lies in the greenhouse effect. Solar radiation passes through the atmosphere and warms the Earth's surface. The warmed surface emits infrared radiation back upward. GHGs in the atmosphere absorb this infrared radiation and re-emit it in all directions, including back toward the surface. This process keeps the Earth warm enough to support life. The enhanced greenhouse effect occurs when human activities increase the concentration of GHGs, trapping more heat than normal and raising global temperatures. CO₂ accumulates because natural processes cannot absorb all the carbon we emit: land vegetation and oceans together absorb about half of annual human CO₂ emissions, but the rest remains in the atmosphere, building up year after year. In Nigeria, the burning of fossil fuels,
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