Assignment Code: MEV-021/TMA/2020/2021-22

Course Code: MEV-021

Assignment Name: Introduction to Climate Change

Year: 2021-2022

Verification Status: Verified by Professor

Q1. Write short notes on the following:

a. Structure of the atmosphere

Ans) There are five layers in the structure of the atmosphere depending upon temperature. These layers are:

Troposphere

1. It is considered as the lowest layer of Earth’s atmosphere.

2. The troposphere starts at the surface of the earth and goes up to a height of 8 kms (poles) to 18 kms (equator). The main reason of higher height at the equator is due to presence of hot convection currents that push the gases upward.

3. All kinds of weather changes occurs within this layer.

4. This layer has water vapor and mature particles.

5. Temperature decreases with increasing height of atmosphere at the rate of 1 degree Celsius for every 165 m of height. This is called Normal lapse rate.

6. Tropopause, the transitional zone, separates Troposphere and Stratosphere.

Stratosphere

1. It is the second layer of the atmosphere found above the troposphere.

2. It extends up to a height of 50 km from the earth’s surface.

3. This layer is very dry as it contains little water vapour.

4. This layer provides some advantages for flight because it is above stormy weather and has steady, strong, horizontal winds.

5. The ozone layer is found in this layer.

6. The ozone layer absorbs UV rays and safeguards earth from harmful radiation.

7. Stratopause separates Stratosphere and Mesosphere.

Mesosphere

1. The Mesosphere is found above the stratosphere.

2. It is the coldest of the atmospheric layers.

3. The mesosphere starts at 50 km above the surface of Earth and goes up to 80 km.

4. The temperature drops with altitude in this layer.

5. By 80 km it reaches -100 degrees Celsius.

6. Meteors burn up in this layer.

7. The upper limit is called Mesopause which separates Mesosphere and Thermosphere.

Thermosphere

1. This layer is found above Mesopause from 80 to 400 km.

2. Radio waves that are transmitted from the earth are reflected by this layer.

3. The temperature starts increasing again with increasing height in this layer.

4. Aurora and satellites occur in this layer.

5. Ionosphere

6. The lower Thermosphere is called the Ionosphere.

7. The ionosphere consists of electrically charged particles known as ions.

8. This layer is defined as the layer of the atmosphere of Earth that is ionized by cosmic and solar radiation.

9. It is positioned between 80 and 400 km above the Mesopause.

Exosphere

1. It is the outermost layer of the atmosphere.

2. The zone where molecules and atoms escape into space is mentioned as the exosphere.

3. It extends from the top of the thermosphere up to 10,000 km.

Q1. b. Greenhouse Effect

Ans) While solar radiation is largely short-wave, long-wave, or infrared, radiation is emitted from the earth's surface. The atmosphere is absorbent to infrared and long-wave radiation, except between roughly 8.5 and 13.0 m – the 'atmospheric window' – due to the presence of gases such as water vapour, carbon dioxide, and other trace gases. "The greenhouse effect" is the opaqueness of the atmosphere to infrared radiation compared to its transparency to short-wave radiation. In other words, the greenhouse effect refers to "all infrared-absorbing elements in the atmosphere's infrared radiative effect."

Terrestrial radiation released from the Earth's surface and elsewhere in the atmosphere is absorbed by greenhouse gases, clouds, and (to a lesser extent) aerosols. The size of this effect grows as the concentration of greenhouse gases rises." Greenhouse gases are "those gaseous constituents of the atmosphere, both natural and anthropogenic, that absorb and emit radiation at specific wavelengths within the spectrum of terrestrial radiation emitted by the Earth's surface, the atmosphere itself, and clouds at specific wavelengths within the spectrum of terrestrial radiation emitted by the Earth's surface, the atmosphere itself, and clouds."

The principal greenhouse gases in the Earth's atmosphere are water vapour (H2O), carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4), and ozone (O3)." Human-made greenhouse gases including halocarbons and other chlorine- and bromine-containing compounds, as well as sulphur hexafluoride (SF6), are other key radiatively active gases to consider. Instantaneous radiative forcing is induced by human-made greenhouse gas emissions. "In response to this forcing, the surface temperature and troposphere warm, gradually restoring the radiative balance at the top of the atmosphere."

It's worth noting that the natural greenhouse effect is a result of the natural atmospheric gas constituents' infrared radiation absorbing capabilities, such as water vapour, carbon dioxide, and methane. Because the global surface air temperature is 15 degrees Celsius, natural greenhouse gases are to blame for making the Earth a liveable world. In other words, if these gases had not existed, the earth's average temperature would have been around 34 degrees Celsius lower than it is now, and the globe would have been a frozen and uninhabitable planet.

Q3. Write short notes on the following:

a. Natural drivers of climate change

Ans) Sunspots are relatively cool, dark spots that form 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 light. The sun experiences a solar maximum and a solar minimum throughout this time. The sun has the most sunspots and solar flares at a solar maximum, and it emits the most energy. A solar low has fewer sunspots and solar flares than a solar maximum. It produces less energy. Nonetheless, there was a lot of carbon dioxide in the atmosphere back then. As a result, there is a wide range of solar activity.

Orbital Variations: Milutin Milankovitch hypothesised the link between orbital variations and Earth's climate in 1930. In fact, orbital oscillations have an impact on the amount of solar energy that reaches the earth's surface, as well as the distribution of sunshine across areas and seasons. Milankovitch oscillations are crucial for understanding past climate, particularly during ice ages and interglacial eras. The eccentricity of the orbit is the term for this. The solar energy received on the earth surface changes between perihelion and aphelion due to the eccentricity of the earth's orbit around the sun.

Nonetheless, the air circulation, as well as continentality, obscure this difference in solar energy receipt.

Tectonic Activities: On a geological time scale, you can see how the positions of continents and oceans have altered owing to earth processes. Plate tectonics is a popular term for the idea that explains how continents and oceans move. These lithospheric plate movements have resulted in the construction of mountains, as well as changes in the size and placement of mountain ranges and plateaus. The atmospheric circulation pattern, as well as the ocean circulation, has been affected as a result of this.

Large amounts of sulphur dioxide, water vapour, ash, and dust particles are released into the atmosphere as a result of volcanic eruptions. The microscopic ash and dust particles in the atmosphere produce aerosols, which reflect solar radiation back into space and cool the earth. "Equatorial eruption plumes travel throughout both hemispheres, whereas plumes from mid- to high-latitude eruptions are confined to that hemisphere." For at least the last 150,000 years, records of such eruptions have been preserved in the Antarctic and Greenland ice sheets. Major eruptions cause a hemisphere/global cooling of 0.5 to 1.0°C in the year following the event, according to observational evidence from the last 100 years, but there is substantial regional variability."

Q3. b. “Water vapour feedback” and “Lapse-rate feedback”

Ans) Water Vapour Feedback: The most abundant radiatively active gas in the atmosphere is water vapour. It is responsible for the atmosphere's infrared opacity. It's crucial to know the atmospheric concentration of water vapour in the case that other greenhouse gases cause global warming and climate change, because increases in GHGs other than water vapour will have a positive effect on the concentration of water vapour. When studied in isolation from other climate feedbacks, climate model studies show that water vapour feedback is a major positive feedback that increases the sensitivity of surface temperatures to carbon dioxide by nearly a factor of two. When the temperature warms, the amount of water vapour in the atmosphere rises, amplifying the greenhouse effect and causing even more heat. This is a very positive response. While water vapour feedback is said to be strongest in the tropics, because the tropical environment favours higher air temperature and maximum water vapour concentration, water vapour feedback is said to be weaker in the Polar Regions.

Lapse-rate Feedback: The "rate of change of an atmospheric variable, usually temperature, with height" is characterised as the lapse rate. When an atmospheric variable decreases with height, the lapse rate is considered to be positive. The rate of decline in air temperature in the troposphere with height influences the strength of the greenhouse effect. To put it another way, a higher lapse rate means a greater greenhouse impact. Radiative processes, large-scale dynamical processes, and convection all influence the lapse rate. The moist adiabatic lapse rate is supposed to decrease with increasing surface temperature in tropical locations, and so the lapse rate feedback is considered to be negative (NRC 2003). The upper troposphere experiences the largest temperature variations when the lapse rate is negative. Positive lapse rate feedback, on the other hand, is stated to occur when bigger temperature changes are recorded at the surface.

Q4. Write short notes on the following:

a. Urban Heat Island Effect

Ans) The Metropolitan Heat Island (UHI) effect is caused by anthropogenic waste heat emissions raising the temperature in urban areas above that of nearby locations. Due to direct heat output from human activities, loss of vegetation, development of buildings, roads, pavement, and other human alterations of the natural environment, the temperature of urban areas has risen. As a result of the absence of evapotranspiration from trees and increased radiation absorption by the urban canopy, the surface heat was accelerated. The 'Urban Heat Island' effect affects the local climate in metropolitan areas. It has a greater impact on temperature rise than its rural surroundings. Increased population, limited green cover, concrete constructions, vehicular traffic, and industrialisation are all possible causes of this condition.

Buildings and other concrete structures heat up during the day and release heat at night, making urban populations warmer than surrounding rural areas. This phenomenon is known as the 'Urban Heat Island' effect, and it is more prevalent in many urban places. It is well established that UHI contributes to climate change by increasing greenhouse gas emissions. City officials are concerned that the extreme summer heat will make people uncomfortable, as well as limit visitor interest during the summer months. Our most vulnerable groups are generally the first to be affected by extreme heat occurrences. By shading building surfaces, diverting solar radiation, and releasing moisture into the atmosphere, trees, green roofs, and vegetation can assist mitigate urban heat island impacts.

Urban heat islands and global climate change have many of the same effects. During the summer, rising temperatures from urban heat islands have an impact on the environment and quality of life. This phenomena raises energy consumption, pollutes the air, jeopardises human health, and degrades water quality. For every 0.6 C increase in temperature, electric consumption rises by 1.5 to 2% during the peak of UHI. It indicates that 5 to 10% of community electricity demand is used to mitigate for UHI effects. In this situation, power plants must work at a higher capacity, resulting in increased greenhouse gas emissions. These have an impact on human health, respiratory problems, and tiredness. In addition, urban heat islands harm water quality by altering the metabolism of many aquatic organisms, resulting in thermal pollution.

Q4. b. Representation Concentration Pathway

Ans) RCPs (Representative Concentration Pathways) are a series of scenarios used in the IPCC Fifth Assessment Report (AR5) to forecast future climate scenarios using climate models. The name Representative Concentration Pathways comes from the fact that these models were created to depict probable future concentrations of greenhouse gas emissions by providing a pathway that represents the trajectory of GHG emissions to attain a specific radiative forcing by 2100. The amount of energy absorbed and retained in the atmosphere by greenhouse gases and aerosols is referred to as radiative forcing.

As a result, it can be either positive (heating) or negative (cooling), and it is influenced by greenhouse gas and aerosol concentrations, changes in land cover, and total solar irradiation. The IPCC adopted RCP in its Fifth Assessment Report (AR5), which replaced the Special Report on Emissions Scenarios (SRES) estimates based on socioeconomic scenarios used in the Third and Fourth IPCC Assessment Reports. The main distinction is that RCPs fix the emissions trajectory and resulting radiative forcing rather than the socioeconomic situation. These RCPs can then be used to test policy decisions on climate change mitigation and adaptation. Based on the quantity of radiative forcing produced by greenhouse gases until 2100, the following four scenarios are possible.

RCP8.5

1. By 2100, the radiative force will be larger than 8.5 W/m2, according to this scenario.

2. Carbon dioxide concentrations in the atmosphere in 2100 would be 936 parts per million.

3. According to this model, the average temperature increase for 2081-2100 compared to the 1850-1900 baseline is 4.3°C, with a likely range of 3.2-5.4°C.

RCP6

1. After 2100, the radiative forcing is stabilised at around 6 W/m2 in this intermediate stabilisation scenario.

2. Carbon dioxide concentrations in the atmosphere in 2100 would be 670 parts per million.

3. According to this model, the average temperature increase for 2081-2100 compared to the 1850-1900 baseline is 2.8°C, with a predicted temperature range of 2.0-3.7°C.

RCP4.5

1. After 2100, the radiative forcing is stabilised at around 4.5 W/m2 in this intermediate stabilisation scenario.

2. Carbon dioxide concentrations in the atmosphere in 2100 would be 538 parts per million.

3. In comparison to 1986-2005, the average worldwide mean sea level rise for 2081-2100 is 0.47 m, with a plausible range of 0.32-0.63 m.

RCP2.6

1. Radiative forcing peaks at around 3 W m-2 before 2100 in this scenario, then falls.

2. RCP3-PD is another name for it.

3. RCP2.6 attempts to keep warming below 2 degrees Celsius above pre-industrial levels.

Q5. Write short notes on the following:

a. Snow line and Timberline

Ans) The snow line is the line that separates snow-covered ground from snow-free ground. This shift is more visible in mountain habitats, and it may be pinpointed to within a metre in some cases. The location of the snow line is determined by height and latitude. Beyond the tropics, the snowline descends to the poles. For every 1oC increase in temperature, the snowline increases around 150 metres. Due to the increase in latitude from 28° N in Kanchenjunga to 36° N in the Karakoram, the snow line in the Eastern Himalayas and Kumaon Himalayas is roughly 3,500 m above sea level, but the snow line in the Western Himalayas is about 2,500 m above sea level.

Because of the rising temperatures, the duration of snow-covered ground north of 50o N has changed. In this global warming in atmospheric temperature, the loss of Arctic snow cover is unavoidable. According to the reports, the Arctic will only have 40 days of snow cover per year, compared to the current 200 days per year. This could lead to an increase in Arctic warming of more than 10 watts per square metre in the twenty-first century. This rise is around 2.5 times greater than the warming predicted by doubling carbon dioxide concentrations in the atmosphere.

Timberline is the most significant vegetation-sensitive habitat in high-mountain locations on all continents, supporting high altitude limits. The upper limit of closed forest on high mountains is known as the timberline. The timber line is the elevation above which no trees can grow due to harsh weather, a lack of oxygen, a lack of temperature, and a lack of moisture. The ecotone between the treeless alpine high temperate and low alpine biodiversity aspects is formed by the higher timberline.

The tree limit ecocline is the climatically sensitive zone between the timberline and alpine ecosystems, indicated by the presence of trees >2 m tall, as well as shrub and herbaceous species. Warmer temperatures have caused the tree line to expand across Russia, Canada, and Alaska. As a result, the forest's edge is referred to as the tree line. We can see young trees and ancient dwarf trees spread above this line. Warm temperatures have shifted the tree line upslope in hilly areas of Scandinavia over the previous 50 years, according to reports.

Q5. b. Methane Clathrates

Ans) Clathrate hydrates are prevalent in nature in (sub)permafrost zones and on the seafloor of continental edges, where they form under pressure and at somewhat low temperatures. Methane is the most abundant confined gas in clathrate hydrates. Methane clathrates, often known as hydrates, are ice-encrusted natural gas reserves found deep down in permeable rocks. As a result, it has turned into an icy substance. It can be found in large quantities in arctic tundra, deep beneath the permafrost, and deep ocean deposits on the continental slope and ocean floor.

Methane clathrates are a good source of energy, but their decomposition, which destabilises the seafloor and emits greenhouse gases, has rendered them a potential geological and climate concern. According to the IPCC's fifth assessment report, methane is 84 times more potent than CO2 per unit mass in a 20-year time frame and 25 times more potent in a 100-year time frame. Temperature and pressure changes impact the stability of methane hydrates, and as a result of this instability, methane escapes into the atmosphere.

Ocean Hydrates: Ocean sediments, notably those in the Arctic Ocean, are a key source of methane hydrates. This methane hydrate can travel up to the seafloor, forming large solid lenses of frozen gas hydrate in areas where methane production is particularly active. Oceanic gas hydrate deposits are thought to store between 2000 and 5000 billion metric tonnes of carbon as methane, with a maximum limit estimate of 10,000 billion metric tonnes.

Gas Hydrates in Permafrost Soils: Permafrost soils, particularly in Arctic permafrost, contain hydrate deposits. The hydrate's stability is determined by high pressure, sediment permeability, and soil permeability. Ground water freezing creates a sealed ice layer, which raises pressure in pore pores in the rock or soil below. Methane hydrate deposits in permafrost soils are estimated to be between 7.5 and 400 billion metric tonnes of carbon. The concentration of dissolved methane in oceans around the continental shelf was 25 times higher than the air concentration. This raises the possibility of methane hydrates escaping and methane emissions from thawing permafrost in shallow marine environments, as well as biological activity.

Q6. Write short notes on the following:

a. The Kyoto protocol

Ans) On December 11, 1997, at the Kyoto Conference, the UNFCCC adopted a treaty (Japan COP). In February 2005, the Kyoto Protocol, as it is known, went into effect. A country can use this to fund carbon-cutting initiatives in another country, so offsetting its own emissions. Similarly, a country might purchase carbon credits from another that has amassed them through emission reductions or other means. The convention also established a fund to assist developing nations in adapting to changing climate conditions.

The Kyoto Protocol also aids countries in responding to climate change's negative effects. It makes it easier to develop and deploy solutions that can help people become more resilient to the effects of climate change. The Kyoto Protocol Adaptation Fund was designed to fund adaptation projects and programmes in developing countries that are Kyoto Protocol signatories. The fund is primarily funded by a portion of project proceeds from the Clean Development Mechanism. The Kyoto Protocol only applies to industrialised countries. It does not, however, include any responsibilities for underdeveloped countries to reduce greenhouse gas emissions.

As a result, the protocol has sparked heated debate on the subject of climate change equality. The majority of the disputes in this context centred on the notion of universal obligations for all states to cooperate and safeguard the environment. As Atapattu points out, it's vital to remember the Rio Declaration's language, which emphasises the states' shared responsibility to safeguard the environment. This underlines two aspects of the climate change debate: global partnership in environmental preservation; and the commitment to protect the environment shared by both developing and industrialised countries.

The Kyoto Protocol is widely regarded as a critical first step toward a truly global emission reduction regime that will stabilise greenhouse gas emissions while also laying the groundwork for any future international climate change deal. By the conclusion of the Kyoto Protocol's first commitment period in 2012, a new international framework must be negotiated and ratified that can achieve the substantial emission reductions that the Intergovernmental Panel on Climate Change has recommended.

Q6. b. India’s National Action Plan on Climate Change

Ans) In 2008, India's first Climate Change Action Plan was established, concentrating on adaptation and mitigation policies and programmes. In the areas of sustainable agriculture, water, the Himalayan Ecosystem, improved energy efficiency, and the accumulation of strategic information on climate change, the plan proposes eight essential national missions to be fulfilled as part of adaptation measures for climate change. The strategy identifies methods to boost economic growth and living standards while also providing co-benefits for effectively tackling climate change.

Domestic and foreign investors are playing a vital role in developing alternative efficient solutions to deal with climate change as a result of the economic liberalisation programme. As a result of the liberalisation of imports, joint ventures may now provide a wide range of consumer goods, such as energy-efficient vehicles and refrigerators, to the market. In the buyers' market, consumers are exhibiting preference for energy-efficient products and exercising their choice. Alternative fuels are becoming more popular in the energy sector.

For example, natural gas is now permitted in the power industry, and coal-fired power plants have become obsolete. In the current situation, India is taking an active and decisive role in climate change negotiations. Although India's viewpoint is not difficult to appreciate, certain problems have arisen in the climate change negotiating discourse. Questions include what concentration level is acceptable to poor countries, how do developing countries access emission reduction obligations, and how do you ensure that India has a fair piece of the global environmental pie, among others.

India’s Position in the Climate Change Dialogue

1. Developing countries, such as India, believe that the industrialised countries' unsustainable consumption patterns are to blame for climate change.

2. The economy of India and other developing countries is vulnerable to climate change, and the effects of climate change might stymie progress in poverty eradication and the country's socio-ecological state.

3. Developing countries can help to reduce GHG emissions by promoting effective programmes such as policies aimed at effective energy and economic management, the development of both conventional and renewable energy resources, and the reduction of health risks.

4. Developing countries have implemented price reforms and eliminated subsidies that have had a good influence on energy conservation.

5. In terms of differentiated responsibility, countries like India must stabilise carbon emissions and strive to reduce GHG concentrations to a level that is sustainable.