Assignment Code: MEV-021/TMA/2022-23

Course Code: MEV-021

Assignment Name: Introduction to Climate Change

Year: 2022-2023

Verification Status: Verified by Professor

Answer any five questions. All question carries equal marks. The marks for each question are indicated against it within brackets on the right-hand side.

Please write all answers in your own words.

Q 1. Write short notes on the following: (20 marks)

Q 1. a. Atmospheric composition

Ans) The most important component of the climate system is the earth's atmosphere. The atmosphere is a gas mixture held to the earth by gravitational attraction. The composition of the atmosphere does not remain constant over time and space. Nitrogen (78.01 percent), oxygen (20.9 percent), Argon (0.93 percent), and carbon dioxide are the main component gases of dry air by volume (0.04 percent). Global climate change and stratospheric ozone depletion are caused by less than 1% of the air, which contains carbon dioxide, methane, nitrous oxide, ozone, and particulate matter. The lower atmosphere is referred to as the homosphere because its chemical composition is uniform. The lighter gases are unable to separate to form individual layers in the lower atmosphere due to constant mixing and turbulence.

At heights greater than 100 km (heterosphere), however, due to the lack of mixing and turbulence, atmospheric gases separate to form concentric layers such as the nitrogen layer (100 - 200 km), oxygen layer (200 - 1100 km), and helium layer (1100 - 3500 km). The earth's atmosphere contributes to the survival of life on Earth by blocking harmful ultraviolet radiation and providing oxygen and carbon dioxide to living organisms and a liveable environment. The presence of radiatively active gases in the atmosphere causes the earth's surface temperature to be around 150 degrees Celsius.

The atmosphere is a gaseous mixture. It also contains a large number of solid and liquid particles known as aerosols. Some gases, which may be considered permanent components of the atmosphere, exist in a fixed proportion to the total gas volume. Other constituents vary in quantity from location to location and over time. About 99 percent of the clean dry air is made up of two gases: nitrogen and oxygen. The remaining gases are mostly inert, accounting for about 1% of the atmosphere. About 21% of it is oxygen, which aids in combustion and heating and without which we cannot live. The majority of the atmosphere is composed of nitrogen, an inert gas that dilutes oxygen and slows the oxidation process.

A small amount of carbon dioxide is used by plants during the photosynthesis process. It transmits incoming solar radiation but absorbs outgoing terrestrial radiation. It absorbs some terrestrial radiation and reflects some of it back to the earth's surface. It is primarily to blame for the greenhouse effect. This gas absorbs heat, allowing heat radiation from the sun and the earth's surface to warm the lower atmosphere. Because it is the heaviest of all atmospheric gases, the lower layers of the atmosphere contain far more CO2 than the upper layers.

Ozone is another important gaseous component of the atmosphere that can be found between 10 and 50 kilometres above the earth's surface. It acts as a filter, absorbing ultraviolet rays emitted by the sun and preventing them from reaching the earth's surface. There is also argon, ammonia, and water vapour present. The percentage of these gases varies slightly across the globe.

Q 1. b. Environmental degradation

Ans) Environmental degradation is the deterioration of the environment caused by the depletion of resources such as air, water, and soil quality; the destruction of ecosystems; habitat destruction; wildlife extinction; and pollution. It is defined as any change or disturbance to the environment that is deemed detrimental or undesirable. Environmental concerns are the negative consequences of any human activity on the environment. The biological and physical characteristics of the environment are both considered. Air pollution, water pollution, natural environment pollution, garbage pollution, and other major environmental issues are causing widespread concern.

Environmental degradation is one of the ten threats officially warned by the United Nations' high-level Panel on Threats, Challenges, and Change. Environmental degradation is defined by the United Nations International Strategy for Disaster Reduction as "the reduction of the environment's capacity to meet social and ecological objectives and needs." There are various types of environmental degradation. The environment is degraded when natural habitats are destroyed, or natural resources are depleted. Efforts to address this issue include environmental protection and resource management. Mismanagement that results in degradation can also lead to environmental conflict, in which communities’ band together to oppose the forces that mismanaged the environment.

Schurr and Abott hypothesised that a high warming scenario would degrade 9-15 percent of the top 3 metres of permafrost by 2040, rising to 47-61 percent by 2100 and 67-79 percent by 2300, with 95 percent confidence intervals around the group's mean estimate. This permafrost melting can produce large amounts of CO2 and CH4, which are measured in billions of tonnes of carbon in CO2 equivalents. Carbon release from this degradation is estimated to be 30-63 billion tonnes over the next three decades, rising to 234-380 billion tonnes by 2100 and 549-865 billion tonnes over the next several centuries.

Forests are the habitat for 80 percent of terrestrial biodiversity, provide livelihoods for approximately 1.6 billion people, act as carbon sinks, and aid in climate change mitigation. Forest loss and degradation raise the level of carbon dioxide in the atmosphere. Deforestation and degradation have an impact on the annual absorption of 2.4 billion tonnes of CO2 emitted by fossil fuel combustion. Deforestation contributed roughly two billion tonnes of carbon to the atmosphere each year. The increase in the albedo of the land surface has an impact on the radiation budget. It also has an impact on wind flow, wind velocity, and water vapour exchange. Rainfall pattern and intensity are both affected. Deforestation exacerbates drought and desertification, crop failures, polar ice cap melting, coastal flooding, and the displacement of major vegetation regimes.

Q 3. Write short notes on the following: (20 marks)

Q 3. a. Natural drivers of climate change

Ans) Geological records show that the Earth's climate has changed dramatically over time. Many natural factors have contributed to this, including changes in the sun, volcanic emissions, variations in Earth's orbit, and carbon dioxide levels.

1. Solar Variability

The sun's energy appears to be constant, but it changes slowly over time. Solar flares and sunspots are examples of different types of solar activity. Sunspots are relatively cool, dark spots that appear in groups on the sun's surface on a regular basis, whereas solar flares are storms or eruptions of hot gases from the sun's surface, accompanied by a burst of ultraviolet radiation. The frequency of sunspots, solar flares, and other solar activity varies over an 11-year period on the sun. During this time, the sun experiences a solar maximum and a solar minimum. During a solar maximum, the sun has the most sunspots and solar flares and emits the most energy. A solar minimum has fewer sunspots and solar flares than a solar maximum. It emits less energy. The Earth's climate is affected by solar activity.

2. Orbital Variations

Milutin Milankovitch proposed the relationship between orbital variations and Earth's climate in the 1930s. Indeed, orbital variations affect the amount of solar radiation reaching the earth's surface, as well as the distribution of sunlight across regions and seasons. Milankovitch oscillations are important for understanding past climate, including ice ages and interglacial periods. With a period of about 100,000 years, the shape of the Earth's orbit oscillates from elliptical to circular. This is referred to as orbital eccentricity. At the moment, the aphelion occurs during the summer in the northern hemisphere." The obliquity of the earth varies between 21.5 degrees and 24.5 degrees over a period of approximately 41,000 years. Precession, or wobbling of the Earth's spin axis, occurs over a 23,000-year period.

3. Tectonic Processes

When viewed on a geological time scale, earth processes move continents and oceans. Plate tectonics explains continent and ocean movement. These lithospheric plate movements caused mountain formation and changes in mountain ranges and plateaus. This affects atmospheric and ocean circulation. According to reports, changes in continental location caused the Permo-Carboniferous glaciation of Gondwanaland. Desertification in western China and Central Asia is attributed to the Himalayas and Tibetan Plateau.

4. Volcanic Eruptions

Volcanic eruptions emit sulphur dioxide, water vapour, ash, and dust. Ash and dust particles in the atmosphere form aerosols, which reflect solar energy back into space and cool the planet. "Plumes from equatorial eruptions spread into both hemispheres, whereas mid- to high-latitude eruptions are confined to that hemisphere." For 150,000 years ago, Antarctic and Greenland ice sheets have recorded such eruptions. Major eruptions cause a hemisphere/global cooling of 0.5 to 1.0°C in the year following the event, but there is regional variability. The 1992-1994 cool spell was caused by Mt. Pinatubo's eruption.

Q 3. b. Anthropogenic drivers of climate change

Ans) It is becoming more common knowledge that human activity is a significant contributor to changes in the environment, most notably climate change. There are a few striking variables that are influenced by human activities, and these changes are responsible for bringing about a change in the climate system. These changes include shifts in atmospheric composition, shifts in land-use and land cover, and shifts in aerosol loading in the atmosphere. Both the rise in the concentration of greenhouse gases and the other changes that have taken place in terrestrial ecosystems are working to raise the levels of radiative forcing and global temperatures.

1.  Atmospheric Composition

Radiatively active gases, trends in GHG concentrations in the atmosphere, and human-caused climate change all influence atmospheric composition. The natural greenhouse effect is also caused by water vapour and other naturally occurring greenhouse gases. Furthermore, the post-industrialization increase in GHG concentrations is primarily due to human activity. The extent to which each GHG perturbs the climate system over a given time period is determined by the gas's concentration in the atmosphere and its radiative forcing.

The most significant contribution comes from the use of fossil fuels, primarily for transportation, building heating and cooling, and industrial applications. Over the last few centuries, the combined radiative forcing of carbon dioxide, methane, and nitrous oxide has increased dramatically. Their rise over the last four decades has been at least six times faster than that of the previous two millennia. Human activities are thought to have contributed to about 1.0°C of global warming above pre-industrial levels, with a likely range of 0.8°C to 1.2°C.

2. Changes in Land-use

Land use can shift for a variety of reasons, including but not limited to urbanisation, agriculture, and industrialization, and these shifts can happen for a variety of reasons. These changes bring about modifications to the land cover, with deforestation being the most noticeable and significant of these modifications. It has an effect on the pattern of rainfall, as well as the pattern of soil and land degradation. The composition of the atmosphere is altered, and the water cycle is disrupted as a direct result of deforestation, which also has an effect on climate. "The anthropogenically induced change in land use has resulted in an increased land surface albedo, which leads to an RF of –0.15 0.10 W m–2."

3. Changes in Aerosol Level

Aerosols are very small particles that are suspended in the air and are known as atmospheric aerosols. Either the dispersion of material at the earth's surface, which results in primary aerosols, or the reaction of gases in the atmosphere leads to the formation of secondary aerosols (secondary aerosols). They include sulphate and nitrates, which are products of the oxidation of sulphur dioxide and nitric oxide, respectively, during the burning of fossil fuels; organic materials, which are products of the oxidation of VOCs (Volatile Organic Compounds); soot, which is a by-product of fires; and mineral dust, which is a by-product of wind-blown processes caused by Radiative Forcing. In addition to increasing the scattering of solar radiation, interacting with atmospheric gases, and the indirect effect that cloud condensation nuclei have on cloud albedo are some of the ways in which aerosols have an impact on climate.

Q 4. Write short notes on the following: (20 marks)

Q 4. a. “Cloud feedback” and “Lapse-rate feedback”

Ans) The concept of feedback is critical in determining whether a perturbation to a system is amplified or dampened by internal system mechanisms.

Cloud Feedback

Cloud feedbacks are an intriguing set of climate feedbacks because they are a major source of uncertainty in climate change predictions, and cloud processes themselves are difficult to understand. This makes cloud feedbacks an intriguing set of climate feedbacks. There are many different types of cloud processes, some of which include cloud microphysical processes, radiative processes, dynamical processes, turbulence processes, and chemical processes. Because these processes have the potential to influence climate feedbacks, the global climate system gives them significant consideration because of this potential.

Warming of the surface may result in the formation of additional clouds, and the increased albedo that results from the formation of additional clouds may result in a decrease in the air temperature at the surface. This type of feedback is known as negative feedback because it has the effect of reducing the initial perturbation, which was surface warming. In spite of this, the fact that clouds are made of water vapour means that an increase in cloud formation as a result of surface warming may result in an increase in the atmospheric water vapour content, which in turn may lead to even more surface warming. This is a constructive way of responding. In modelling studies, it is a challenging task to consider both the positive and negative feedback effects of cloud feedback. This contributes to the uncertainty that exists in projections regarding climate change. On the other hand, cloud feedback is thought to have a positive overall effect.

Lapse-Rate Feedback

The lapse rate is defined as the "rate of change of an atmospheric variable, usually temperature, with height." Lapse rates are typically measured in metres per hour. Positive lapse rates are described as occurring when the value of the atmospheric variable drops with increasing altitude. The intensity of the greenhouse effect is influenced by the rate at which the temperature of the atmosphere in the troposphere decreases with increasing altitude. To put it another way, a higher lapse rate leads to a greater amount of greenhouse effect.

The "radiative processes," the "large-scale dynamical processes," and the "convection" all contribute to the lapse rate in their own unique ways. In tropical regions, it has been observed that the moist adiabatic lapse rate decreases as the surface temperature rises, which suggests that the lapse rate feedback has a negative value. When the lapse rate is decreasing, the upper troposphere experiences larger temperature shifts than it would otherwise. On the other hand, positive lapse rate feedback is said to take place when larger temperature changes are observed at the surface.

Q 4. b. Representative Concentration Pathway

Ans) RCPs, or Representative Concentration Pathways, are models that depict the future of potential carbon dioxide emissions or the possible reduction of atmospheric concentrations over the current century. Representative Concentration Pathways are developed based on current century predictions, with multiple scenarios developed ranging from the best-case scenario to the worst-case scenario in how carbon dioxide emissions will impact the world across multiple sectors.

RCP accomplishes this by incorporating a wide range of possible climate policy outcomes for the current century. Researchers use the predictions to conduct additional research after limiting the number of possible carbon dioxide emission scenarios. Finally, the researchers use their scientific findings on carbon dioxide emissions to develop scenarios for the future global impact of climate change.

Four different sectors are targeted by Representative Concentration Pathways. Population, economic growth, and energy consumption are among the topics covered in this century's research and data. RCP models, in particular, attempt to forecast future population growth, forest, grass, and crop land use, oil and fossil fuel usage, and the prevalence of renewable energy sources as a result of potential increases or decreases in carbon dioxide emissions in the atmosphere.

Many factors must be considered in order to produce an accurate representation of future carbon dioxide emissions in order to predict the future of global warming. The most important aspect of this model is the use of potential future greenhouse gas emissions as a variable in an RCP. When developing an RCP, it is also necessary to consider ongoing technological developments, energy generation that is subject to change depending on the land's current use, and economic components such as population growth and urbanisation.

The primary goal of RCP is to forecast future trends in greenhouse gas emissions of carbon dioxide emissions and how they will affect the atmosphere, ozone layer, oil and fossil fuel use, urbanisation, overall human activity, and the progress of developing countries in order to course correct for the most appropriate and efficacious environmental outcomes possible. As a result, the goal of RCP is to outline all potential scenarios as well as the precautionary measures that can be taken ahead of time.

Q 5. Explain the sources of palaeoclimatic data. (20 marks)

Ans) Natural sources of paleoclimatology data include tree rings, ice cores, corals, and ocean and lake sediments.

1. Historical Data

It is the first source of data for reconstructing past climates. It is made up of documentary data. Historical data is derived from farmer's logs, traveller's diaries, ancient inscriptions, newspapers, paintings, artistic depictions, early weather observers' reports, and other public records. Aside from these, legal documents, written accounts, tax records, economic records, and pictorial records containing information about land uses, landscape, societal collapse, construction materials, and biodiversity can help reconstruct past/ancient climate.

Furthermore, any records containing information on the timings of forests and tree flowering, occurrences of snowfall, rainfall, drought, famine, and flood, as well as bird migration, are all examples of historical data. Historical climate data provide both qualitative and quantitative information about the past. This data provides climatic information of events recorded by humans, such as the Mesopotamian civilization of the Middle East, which was thought to be one of the first civilizations to record events.

2. Archaeological Data

Archaeology is the study of ancient human cultures. It focuses on how people used to live, work, trade, and move. Archaeologists are archaeologists who specialise in archaeology. They use archaeological data to learn how prehistoric humans' lifestyles were influenced by climatic conditions. It should be noted that archaeological data is much older than historical data because archaeological data encompasses a period of ancient cultures that are reconstructed using scientific analyses of numerous soil layers containing human artefacts.

In other words, archaeological time is based on the remains of human life, as opposed to historical data, which is based on human records. An archaeological site is a location where the traces of past human activity have been preserved, and these traces are a valuable source of cultural and non-cultural information, which together comprise the archaeological data. Environmental archaeology is the branch of archaeology concerned with the reconstruction of the past environment, including climate.

3. Geological Record

Geology is the science that studies the earth's origin, evolution, age, structure, composition, and processes that have occurred since its formation approximately 4.6 billion years ago. Geologists are scientists who study the earth's materials. The earth's material, which includes various types of rocks (igneous, sedimentary, and metamorphic), fossils, sediments, and soils that geologists can study. This material, also known as rock record, yields many proxies or indirect evidence that can be used to reconstruct the timeline of the Earth's climate throughout the geological past. It should be noted that the geological record predates historical and archaeological data. Throughout Earth's 4.6-billion-year history, there have been numerous intervals of short and long-term climatic fluctuations, leaving many climatic proxies or natural archives preserved in the rock record. Sedimentary rock types, fossils, and ice core and cave deposits are among the most important natural archives.

Sedimentary Rock Types: Sedimentary rocks are formed by the slow deposition of sediments carried by rivers and streams into oceans and other bodies of water (e.g., rivers or lakes), which consolidated into stratified (layered) hard rocks over millions of years. The sedimentary rocks are made up of these rock bodies.

Fossils: These are ancient life remains preserved in sedimentary rocks. As we all know, some organisms, particularly animals and plants, are extremely dependent on environmental conditions, and many of them are only narrowly adapted to specific climatic conditions. As a result, their fossils provide valuable information about past climates.

Ice Cores: They include ice cores obtained by drilling glaciers and ice sheets in perennially cold areas with little or no melting, such as the Polar Regions, northern Greenland, and the high mountains of the Andes and the Himalaya. Drilled ice cores are used to study air bubbles, water, and material trapped in them, such as ancient atmospheric oxygen, hydrogen, carbon dioxide, and dust and ash particles, using a variety of methods. Ice cores are a valuable source of past climate data dating back thousands of years.

Cave Deposits: These are calcium carbonate deposits made up of speleothems (stalagmites, stalactites, and flowstones) that formed in a limestone cave and could be used to predict non-glacial terrestrial climate. Secondary mineral deposits formed by groundwater within underground caverns form speleothems. The speleothems have different types of annual laminas and retain seasonality. Each laminae's oxygen and carbon stable isotopic analyses reveal information about past rainfall, vegetation, and other climatic factors. Cave deposits contain palaeoclimatic evidence from around 30,000 years ago.

The understanding and study of natural archives, as well as the methods used in their analysis, are required for the reconstruction of past climates. As a result, it is not necessary that our interpretation of proxy data is always correct.

Q 6. Explain the features of the Paris Agreement on Climate Change. (20 marks)

Ans) The landmark international accord known as the Paris Agreement was signed in 2015 by nearly all of the world's nations in an effort to address the effects of climate change and potential solutions. The goal of the agreement is to significantly cut global emissions of greenhouse gases in order to keep the rise in global average temperature during this century to no more than 2 degrees Celsius (3.6 degrees Fahrenheit) above preindustrial levels, while also pursuing the means to keep the rise to no more than 1.5 degrees.

The agreement includes pledges from all of the major emitting countries to reduce the amount of climate pollution they produce and to increase the severity of those pledges over time. The pact establishes a framework for the transparent monitoring, reporting, and ratcheting up of countries' individual and collective climate goals, providing a pathway for developed nations to assist developing nations in their climate mitigation and adaptation efforts. Additionally, the pact makes it possible for developed nations to assist developing nations in their climate mitigation and adaptation efforts.

Paris served as the location for the climate change negotiations that took place in December of 2015. It is being negotiated under the auspices of the United Nations, and its goal is to keep the rise in the average temperature of the planet "well below" 2 degrees Celsius above its pre-industrial levels. The agreement serves as a foundation for the COP26 climate talks that are taking place in Glasgow. At its core is a "ratchet mechanism," which stipulates that parties to the agreement must present more aggressive national climate goals on a five-year cycle. As a direct result of this, COP26 is the most significant climate meeting that has taken place since Paris. The most important aspects of the Paris agreement are broken down in the following annotations by our climate team, which also provide links to our previous coverage on the topic.

Indeed, the Paris Agreement is the result of a four-year negotiating process and multilateral diplomacy. Article 2 of the Paris Agreement states that "the agreement aims to strengthen the global response to the threat of climate change, in the context of sustainable development and efforts to eradicate poverty, including by:

1. Keeping the increase in global average temperature well below 2°C above preindustrial levels and pursuing efforts to limit the temperature increase to 1.5°C above preindustrial levels, recognising that doing so would significantly reduce the risks and impacts of climate change.

2. Increasing the ability to adapt to the adverse effects of climate change and promote climate resilience and low-carbon development without jeopardising food production; and

3. Making financial flows consistent with a low-GHG-emissions and climate-resilient development path."

The Paris agreement's main features are universal application, the principle of equity, and the principle of shared but differentiated responsibilities and capabilities, as well as a "legally binding agreement that will apply to those states that have expressed their consent to be bound by means of ratification, acceptance, approval, or accession." The agreement requires India to submit "national contributions" every five years and to embark on a low-carbon development path.

The Paris Agreement presents an action plan to limit global warming. Its main elements are:

1. A long-term goal: governments agreed to keep the increase in global average temperature to well below 2°C above pre-industrial levels and to pursue efforts to limit it to 1.5°C.

2. Contributions: before and during the Paris conference, countries submitted comprehensive national climate action plans (called NDCs – nationally determined contributions) to reduce their emissions.

3. Ambition: governments agreed to communicate their action plans every five years, with each plan setting more ambitious targets.

4. Transparency: countries agreed to report to each other and the public on how well they are doing in reaching their targets, to ensure transparency and oversight.

5. Solidarity: EU member states and other developed countries will continue to provide climate finance to help developing countries to both reduce emissions and build resilience to deal with the effects of climate change.

In the Paris Agreement when the condition of ratification by at least 55 countries accounting for at least 55% of global greenhouse gas emissions was met. All EU countries ratified the agreement.