Environmental Studies (ENV-101) Lecture Notes PDF

Environmental Studies (ENV-101) LECTURE NOTES Prepared by: Dr. Diksha Rana & Dr. Sarika Department of Environmental Science, School of Earth and Environmental Sciences, Amity University Punjab (AUP) Mohali, Punjab  Unit...

Environmental Studies (ENV-101) LECTURE NOTES Prepared by: Dr. Diksha Rana & Dr. Sarika Department of Environmental Science, School of Earth and Environmental Sciences, Amity University Punjab (AUP) Mohali, Punjab  Unit-1 Multidisciplinary Nature of Environmental Studies INTRODUCTION The word Environment is derived from the French word “Environ” which means “surrounding”. Our surrounding includes biotic factors like human beings, Plants, animals, microbes, etc and abiotic factors such as light, air, water, soil, etc. Environment is a complex of many variables, which surrounds man as well as the living organisms. The environment creates favourable conditions for the existence and development of living organisms. The survival of any organism requires a steady supply of materials and removal of waste products. The natural environment encompasses all living and non-living things. This environment encompasses the interaction of all living species, climate, weather, and natural resources that affect human survival and economic activity. Environmental studies are multi-disciplinary because it comprises various branches of studies like chemistry, physics, medical science, life science, agriculture and public health. It is the science of physical phenomena in the environment. Environmental studies deals with every issue that affects an organism. It is an applied science as it’s seeks practical answers to making human civilization sustainable on the earth’s finite resources. The environment is constituted by the interacting systems of physical, biological and cultural elements inter-related in various ways, individually as well as collectively. These elements are (1) Physical Elements: Space, landforms, water bodies, climate, soils, rocks and minerals. They determine the variable character of the human habitat, its opportunities as well as limitations (2) Biological Elements: Plants, animals, microorganisms and human beings constitute the biosphere. (3) Cultural Elements: Economic, social and political elements are essentially manmade features, which constitute the cultural milieu. MULTIDISCIPLINARY NATURE OF ENVIRONMENTAL STUDIES Environmental science is an interdisciplinary academic field that integrates physical and biological sciences, (including but not limited to Ecology, Physics, Chemistry, Biology, Soil Science, Geology, Atmospheric Science and Geography) to the study of the environment, and the solution of environmental problems. Environmental science provides an integrated, quantitative, and interdisciplinary approach to the study of environmental systems. Related areas of study include environmental studies and environmental engineering. Environmental studies incorporate more of the social sciences for understanding human relationships, perceptions and policies towards the environment. Environmental engineering focuses on design and technology for improving environmental quality. Environmental scientists work on subjects like the understanding of earth processes, evaluating alternative energy systems, pollution control and mitigation, natural resource management, and the effects of global climate change. Environmental issues almost always include an interaction of physical, chemical, and biological processes. SCOPE OF ENVIRONMENTAL SCIENCE Because of environmental studies has been seen to be multidisciplinary in nature so it is considered to be a subject with great scope. Environment is not limited to issues of sanitation and health but it is now concerned with pollution control, biodiversity conservation, waste management and conservation of natural resources. This requires expert eyes and hence is creating new job opportunities. The opportunities in this field are immense not only for scientists but also for engineers, biologists. There is a good chance of opportunity to find a job in this field as environmental journalists. Environmental science can be applied in the following spheres: Ecosystem Structure and Function The study of ecosystems mainly consists of the study of the processes that link the leaving organism or in other words biotic component to the non-living organism or a biotic component. So for the study of environment we should aware with biotic and a biotic components. Natural Resource Conservation For managing and maintenance of forests which are natural resources and for the maintenance of wildlife forms task under natural resource conservation. It is also a scope of environmental studies. Environmental Pollution Control With the knowledge of environmental science everybody can control the pollution. He/she can handle the waste management and also look for ways to control pollution on the aspect of pollution control. Environmental management There are several independent environmental consultants who are working with Central and State pollution control Board. They offer advice to solve the problems of environment the optimum solution for the upcoming problems. They give direction for controlling pollution due to industrial development. There are several current consultants who are working with government pollution control boobs, involved in policy making, pollution control and maintenance of ecological balance. The scope of environmental studies in industry Environmental scientist’s work towards maintenance of ecological balance, they also work towards conservation of biodiversity and regulation of natural resources as well as on preservation of natural resources. Most of the industries have a separate environmental research and development section. These sections govern the impact that their industry has on the environment. Our environment is being degraded by the rapid industrialization. To combat this menace there is a growing trend towards manufacture of "green" goods and products. So we can say that there is a good scope in the field of industry from environmental studies. Research and development Research and development have tremendous scope due to increment in public awareness regarding the environment. Various universities and governmental organizations offer a scope for such research. These universities conduct research studies in order to develop the methods toward monitoring and controlling the source of environmental pollution. Due to an increasing threat from global warming, many steps are being undertaken for the reduction of greenhouse gases and the adoption of renewable energy resources. They generate awareness now regarding the use of solar energy for variety of purposes. This provides scope of environmental history in the field of research and development. Social Development NGO (Nongovernmental organizations) help in creating awareness regarding the protection of the environment and making the masses aware of various environmental issues. They also generate a public opinion in this field. They work towards disseminating information and in bringing about changes in political policies that are personally effect the environment. The social dimension of this profession includes controlling population explosion through organizing advisory awareness camps. IMPORTANCE OF ENVIRONMENT SCIENCE The environment studies enlighten us, about the importance of protection and conservation of our indiscriminate release of pollution into the environment. Environment science has become significant for the following reasons: 1.Environment Issues Being of International Importance: It has been well recognized that environment issues like global warming and ozone depletion, acid rain, marine pollution and  biodiversity are not merely national issues but are global issues and hence must be tackled with international efforts and cooperation. 2. Problems Cropped in the Wake of Development Development, in its wake gave birth to Urbanization, Industrial Growth, and Transportation Systems, Agriculture and Housing etc. However, it has become phased out in the developed World. The North, to cleanse their own environment has fact fully, managed to move ‘dirty’ Factories of South. When the West developed, it did so perhaps in ignorance of the Environmental impact of its activities. Evidently such a path is neither practicable nor desirable, even if developing world follows that. 3. Explosively Increase in Pollution World census reflects that one in every seven persons in this planted lives in India. Evidently with 16 per cent of the world's population and only 2.4 per cent of its land area, there is a heavy pressure on the natural resources including land. Agricultural experts have recognized soils health problems like deficiency of micronutrients and organic matter, soil salinity and damage of soil structure. 4. Need to Save Humanity from Extinction It is incumbent upon us to save the humanity from extinction. Consequent to our activities Constricting the environment and depleting the biosphere, in the name of development. 5. Need for Wise Planning of Development Our survival and sustenance depend. Resources withdraw, processing and use of the product have all to by synchronized with the ecological cycles in any plan of development our actions should be planned ecologically for the sustenance of the environment and development. NEED FOR AWARENESS It is essential to make the public aware of the formidable consequences of the Environmental Degradation, if not retorted and reformative measures undertaken would result in the extinction of life. We are facing various environmental challenges. It is essential to get the country acquainted with these challenges so that their acts may be eco-friendly. Some of the challenges are as under: 1. Growing Population A population of over thousands of millions is growing at 2.11 per cent every year. Over 17 million people are added each year. It puts considerable pressure on its natural resources and reduces the gains of development. Hence, the greatest challenge before us is to limit the population growth. Although population control does automatically lead to development, yet the development leads to a decrease in population growth rates. For this development of the women is essential. 2. Poverty India has often been described a rich land with poor people. The poverty and environmental degradation have a nexus between them. The vast majority of our people are directly dependent on the nature resources of the country for their basic needs of food, fuel shelter and fodder. About 40% of our people are still below the poverty line. Environment degradation has adversely affected the poor who depend upon the resources of their immediate surroundings. Thus, the challenge of poverty and the challenge environment degradation are two facets of the same challenge. The population growth is essentially a function of poverty. Because, to the very poor, every child is an earner and helper and global concerns have little relevance for him. 3. Agricultural Growth  The people must be acquainted with the methods to sustain and increase agricultural growth with damaging the environment. High yielding varieties have caused soil salinity and damage to physical structure of soil. 4. Need to Ground water It is essential of rationalizing the use of groundwater. Factors like community wastes, industrial effluents and chemical fertilizers and pesticides have polluted our surface water and affected quality of the groundwater. It is essential to restore the water quality of our rivers and other water bodies as lakes are an important challenge. It so finding our suitable strategies for consecration of water, provision of safe drinking water and keeping water bodies clean which are difficult challenges is essential. 5. Development and Forests Forests serve catchments for the rivers. With increasing demand of water, plan to harness the mighty river through large irrigation projects were made. Certainly, these would submerge forests; displace local people, damage flora and fauna. As such, the dams on the river Narmada, Bhagirathi and elsewhere have become areas of political and scientific Debate. Components of Environment Environment has been classified into four major components: 1. Hydrosphere 2. Lithosphere 3. Atmosphere 4. Biosphere. Hydrosphere includes all water bodies such as lakes, ponds, rivers, streams and ocean etc. Hydrosphere functions in a cyclic nature, which is termed as hydrological cycle or water cycle. Lithosphere means the mantle of rocks constituting the earth’s crust. The earth is a cold spherical solid planet of the solar system, which spins in its axis and revolves around the sun at a certain constant distance.  Lithosphere mainly, contains soil, earth rocks, mountain etc. Lithosphere is divided into three layers-crusts, mantle and core (outer and inner). Atmosphere: The cover of the air, that envelope the earth is known as the atmosphere. Atmosphere is a thin layer which contains gases like oxygen, carbon dioxide etc. and which protects the solid earth and human beings from the harmful radiations of the sun. There are five concentric layers within the atmosphere, which can be differentiated on the basis of temperature and each layer has its own characteristics. These include the troposphere, the stratosphere, the mesosphere, the thermosphere and the exosphere. Biosphere it is otherwise known as the life layer, it refers to all organisms on the earth’s surface and their interaction with water and air. It consists of plants, animals and micro- organisms, ranging from the tiniest microscopic organism to the largest whales in the sea. The richness of biosphere depends upon a number of factors like rainfall, temperature, geographical reference etc. Apart from the physical environmental factors, the man made environment includes human groups, the material infrastructures built by man, the production relationships and institutional systems that he has devised. The social environment shows the way in which human societies have organized themselves and how they function in order to satisfy their needs. Hydrosphere Hydrosphere consists of the water component of the earth which includes oceans, seas, glaciers, lakes, ponds, rivers, streams and underground water. It is estimated that 71 per cent of the total surface area of the earth is covered by water and the land area accounts for only 29 per cent of the total surface area of the earth. It is on account of abundance of water on its surface that the earth is often called a water planet or blue planet. The volume of the world ocean is estimated to be about 1367 million cubic kilometres which is almost 97 per cent of the world’s free water. Such a vast quantity of water can cover the entire globe by a 3.25 km thick layer of water if spread uniformly over the earth’s surface. Water is present in lithosphere, hydrosphere and atmosphere in all its three forms i.e. solid, liquid and gas. It is never static and exists in dynamic condition changing its form and place. Evaporation takes place at the oceanic surface. Water vapours in the atmosphere are condensed and help in the formation of clouds which result in rain, hail, dew, snow or sleet. Some of the precipitation, after wetting the foliage and ground, runs over the surface to the streams. The water which flows in streams causes erosion and excess of water causes floods. Some water soaks into the ground. This water is used for growing plants and is also available for evaporation. Some reaches the deeper zones and percolates and seeps to maintain the streams during dry period. The streams, in turn, eventually, return the water back to the oceans where it originated from. This never ending circulation of water from ocean to the atmosphere, thence to land and back to the oceans is called hydrological cycle. Thus the hydrological cycle interconnects the lithosphere the hydrosphere and in atmosphere.  97% ocean 3% water (fresh) This 3% is divided in following sources : Glacier and Icecap > Ground Water> Inland Lakes > Soil Moisture > Atmosphere > Rivers 8 2 Earth’s Area 5 X 10 km Volume Wise - Pacific > Atlantic > Indian > Arctic In Northern hemisphere 3/5 portion is constituted by water and in Southern hemisphere 4/5 portion is constituted by water. 57% of Total Ocean lies into Southern Hemisphere. This graphic shows several ocean floor features on a scale from 0-35,000 feet below sea level. The following features are shown at example depths to scale, though each feature has a considerable range at which it may occur: continental shelf (300 feet), continental slope (300- 10,000 feet), abyssal plain (>10,000 feet), abyssal hill (3,000 feet up from the abyssal plain), seamount (6,000 feet up from the abyssal plain), ocean trench (36,000 feet), and volcanic island (above sea level). (NOAA Office of Education). Oceans of the World A look at the world map indicates that about 71% of the earth’s surface is covered by oceans. The main oceans of the world in descending order of area and volume are Pacific Ocean Atlantic Ocean, Indian Ocean, Southern Ocean and Arctic Ocean. Submarine Relief The floor of the oceans is not plain, rather it is very rugged and complex consisting of world’s longest mountain ranges, deepest trenches and largest plains. This great variety in the relief of the ocean or is largely due to interaction of tectonic, volcanic, erosional and depositional processes. Ocean Floor The ocean floor can be divided into following four major divisions: 1.The continental shelf. 2.The continental slope. 3.The continental rise. 4.The abyssal plain. Continental Shelf Continental shelf is slightly inclined, inundated zone which structurally forms the border of a continent. It is generally formed by the drowning of part of a continent with a relative rise in sea-level, or marine deposition beneath the water. It has a gentle slope which is less than 1′ and its maximum depth is normally 200 metres. Its width varies with its slope. The continental shelf of steep slope is narrow while that of gentle slope is quite broad. Its average width is about 70 km. It is almost absent in the eastern Pacific, especially in South America. Along the eastern coast of the USA, it is 120 km wide. Its maximum width is o the Arctic Coast of Siberia where it is 1,287 km wide. It covers about 7.5% of the total area of world’s ocean. Continental Slope At the edge of the continental shelf, the seaward slope immediately becomes steep and the angle of slope varies between 2′ and 5′. This part with steep slope is known as continental slope. It extends to a depth of about 3,660 metres. Continental Rise Beyond the continent slope is the continental rise. It is an area of gentle slope varying from 0.5′ to 1′. Its general relief is low. With increasing depth, it virtually becomes at and merges with the abyssal plain. Abyssal Plains Where the continental rise ends, the deep sea plain known as abyssal plain or abyssal floor begins. These are almost at areas with gradient less than 1′. Their depth varies from 3,000 to 6,000 metres. They are extensive areas covering about 40% of the ocean or. They are present in all the major oceans and several seas of the world. Submarine Ridges  These are under water mountain ranges which are a few hundred kilometres wide and several thousand kilometres long. They are ridges of high relief and form the longest mountain system on the earth. Most of the ridges are placed centrally in the oceans. Mid-Atlantic Ridge is the best example. The total length of the submarine ridge system is over 75,000 km. Abyssal Hills There are thousands of hills on the ocean floor which are submerged under ocean water. A submarine mountain or peak rising more than 1,000 metres above the ocean or is known as a seamount. Flat topped seamounts are known as guyots. All these features are of volcanic origin. Pacific ocean has the largest number of seamounts and guyots. It is estimated that there are nearly 10,000 abyssal hills in the Pacific ocean alone. Submarine Trenches or Deeps A trench is a long, narrow and steep sided depression on the ocean or. Trenches are the deepest parts of the ocean bottom with their usual depth of 5,500 metres. e deepest trench of the world is the Marina trench of the Guam Islands which is over 11 kilometres deep. If the Mt. Everest were to be submerged in this trench, its peak would still remain three kilometres below the sea-level. So far 57 trenches have been located out of which 32 are in the Pacific Ocean, 19 in the Atlantic Ocean and the remaining 6 are in the Indian Ocean. Submarine Canyons A submarine canyon is a steep-sided depression on the sea-floor crossing the continental shelf, slope and sometimes continental rise as deep as abyssal waters. The largest canyons in the world occur in the Bering Sea of Alaska. They are the Bering, Pribilof and Zhemchug canyons. Hudson Canyon is the best known canyon in the world. It begins near the mouth of the Hudson river and extends into the Atlantic Ocean. Atmosphere Average Earth’s Temperature: 150C - 200C (288 k) Absence of Green House gases : Average Temperature: -150 C to -200 C Water vapor is the most variable Green House Gas (Both spatial and temporally). Earth’s atmosphere is transparent to short wave radiation of Sun, however long wave radiation emitted from earth’s surface is absorbed by greenhouse gases such as water vapor and carbon dioxide. This phenomenon is called greenhouse effect. One of the main components of Earth’s interdependent physical systems is the atmosphere. An atmosphere is made of the layers of gases surrounding a planet or other celestial body.  Earth’s atmosphere is composed of about 78% nitrogen, 21% oxygen, and 1% other gases. Nitrogen (N2): It is the most plentiful gas in the air. It is one of the primary nutrients critical for the survival of all living organisms. Oxygen (O2): Humans and animals take oxygen from the air as they breathe. Green plants produce oxygen during photosynthesis. In this way oxygen content in the air remains constant. Carbon dioxide (CO2): It is an important heat-trapping gas, or greenhouse gas, that comes from the extraction and burning of fossil fuels. These gases are found in atmospheric layers defined by unique features such as temperature and pressure. Earth’s atmosphere has five major and several secondary layers. From lowest to highest, the major layers are the troposphere, stratosphere, mesosphere, thermosphere and exosphere. Troposphere. Earth’s troposphere extends from Earth’s surface to, on average, about 12 kilometers (7.5 miles) in height, with its height lower at Earth’s poles and higher at the equator. Yet this very shallow layer is tasked with holding all the air plants need for photosynthesis and animals need to breathe, and also contains about 99 percent of all water vapor and aerosols (minute solid or liquid particles suspended in the atmosphere). In the troposphere, temperatures typically go down the higher you go, since most of the heat found in the troposphere is generated by the transfer of energy from Earth’s surface. The troposphere is the densest atmospheric layer, compressed by the weight of the rest of the atmosphere above it. Most of Earth’s weather happens here, and almost all clouds that are generated by weather are found here, with the exception of cumulonimbus thunder clouds, whose tops can rise into the lowest parts of the neighboring stratosphere. Most aviation takes place here, including in the transition region between the troposphere and the stratosphere. Stratosphere. Located between approximately 12 and 50 kilometers (7.5 and 31 miles) above Earth’s surface, the stratosphere is perhaps best known as home to Earth’s ozone layer, which protects us from the Sun’s harmful ultraviolet radiation. Because of that UV radiation, the higher up you go into the stratosphere, the warmer temperatures become. The stratosphere is nearly cloud- and weather-free, but polar stratospheric clouds are sometimes present in its lowest, coldest altitudes. It’s also the highest part of the atmosphere that jet planes can reach. Mesosphere. Located between about 50 and 80 kilometers (31 and 50 miles) above Earth’s surface, the mesosphere gets progressively colder with altitude. In fact, the top of this layer is the coldest place found within the Earth system, with an average temperature of about minus 85 degrees Celsius (minus 120 degrees Fahrenheit). The very scarce water vapor present at the top of the mesosphere forms noctilucent clouds, the highest clouds in Earth’s atmosphere, which can be seen by the naked eye under certain conditions and at certain times of day. Most meteors burn up in this atmospheric layer. Sounding rockets and rocket-powered aircraft can reach the mesosphere. Thermosphere. Located between about 80 and 700 kilometers (50 and 440 miles) above Earth’s surface is the thermosphere, whose lowest part contains the ionosphere. In this layer, temperatures increase with altitude due to the very low density of molecules found here. It is both cloud- and water vapor-free. The aurora borealis and aurora australis are sometimes seen here. The International Space Station orbits in the thermosphere. This temperature increase is caused by the absorption of energetic ultraviolet and X- Ray radiation from the sun. The region of the atmosphere above about 80 km is also caused the "ionosphere", since the energetic solar radiation knocks electrons off molecules and atoms, turning them into "ions" with a positive charge. The temperature of the thermosphere varies between night and day and between the seasons, as do the numbers of ions and electrons which are present. The ionosphere reflects and absorbs radio waves, allowing us to receive shortwave radio broadcasts in New Zealand from other parts of the world. Exosphere. Located between about 700 and 10,000 kilometers (440 and 6,200 miles) above Earth’s surface, the exosphere is the highest layer of Earth’s atmosphere and, at its top, merges with the solar wind. Molecules found here are of extremely low density, so this layer doesn’t behave like a gas, and particles here escape into space. While there’s no weather at all in the exosphere, the aurora borealis and aurora australis are sometimes seen in its lowest part. Most Earth satellites orbit in the exosphere. It contains mainly oxygen and hydrogen atoms, but there are so few of them that they rarely collide - they follow "ballistic" trajectories under the influence of gravity, and some of them escape right out into space. The Magnetosphere The earth behaves like a huge magnet. It traps electrons (negative charge) and protons (positive), concentrating them in two bands about 3,000 and 16,000 km above the globe - the Van Allen "radiation" belts. This outer region surrounding the earth, where charged particles spiral along the magnetic field lines, is called the magnetosphere. The Edge of Outer Space. While there’s really no clear boundary between where Earth’s atmosphere ends and outer space begins, most scientists use a delineation known as the Karman line, located 100 kilometers (62 miles) above Earth’s surface, to denote the transition point, since 99.99997 percent of Earth’s atmosphere lies beneath this point. A February 2019 study using data from the NASA/European Space Agency Solar and Heliospheric Observatory (SOHO) spacecraft suggests, however, that the farthest reaches of Earth’s atmosphere — a cloud of hydrogen atoms called the geocorona — may actually extend nearly 391,000 miles (629,300 kilometers) into space, far beyond the orbit of the Moon. Significance of Atmosphere  Protection from Harmful Radiations: The atmosphere protects life on Earth by shielding it from incoming ultraviolet (UV) radiation, keeping the planet warm through insulation, and preventing extremes between day and night temperatures. Weather and climate: The atmosphere play a crucial role in determining weather and climate patterns, including temperature, precipitation, and wind. These patterns have a significant impact on ecosystems, agriculture, and human activities. Regulates the Earth's Temperature: The atmosphere helps regulate the Earth's temperature by trapping heat from the sun and preventing it from escaping into space. This process, known as the greenhouse effect, helps keep the planet warm enough to support life. A Major Role in the Water Cycle: The atmosphere helps regulate the Earth's water cycle by transporting water vapor from the oceans to the land, where it falls as precipitation. The Earth can be divided into one of two ways – mechanically or chemically. Mechanically – or rheologically, meaning the study of liquid states – it can be divided into the lithosphere, asthenosphere, mesospheric mantle, outer core, and the inner core. But chemically or by composition, which is the more popular of the two, it can be divided into the crust, the mantle (which can be subdivided into the upper and lower mantle), and the core – which can also be subdivided into the outer core, and inner core. Compositional layers of the Earth: Core, mantle, and crust are divisions based on composition. The crust makes up less than 1 percent of Earth by mass, consisting of oceanic crust and continental crust is often more felsic rock. The mantle is hot and represents about 68 percent of Earth’s mass. Finally, the core is mostly iron metal. The core makes up about 31% of the Earth. Crust: It is the outermost solid part of the earth, normally about 8-40 kms thick. It is brittle in nature. Nearly 1% of the earth’s volume and 5% of earth’s mass are made of the crust. The thickness of the crust under the oceanic and continental areas are different. Oceanic crust is thinner (about 5kms) as compared to the continental crust (about 30kms). Major constituent elements of crust are Silica (Si) and Aluminium (Al) and thus, it is often termed as SIAL(Sometimes SIAL is used to refer Lithosphere, which is the region comprising the crust and uppermost solid mantle, also). The mean density of the materials in the crust is 3g/cm3. The discontinuity between the hydrosphere and crust is termed as the Conrad Discontinuity. Mantle: The portion of the interior beyond the crust is called as the mantle. The discontinuity between the crust and mantle is called as the Mohorovich Discontinuity or Moho discontinuity. The mantle is about 2900kms in thickness. Nearly 84% of the earth’s volume and 67% of the earth’s mass is occupied by the mantle. The major constituent elements of the mantle are Silicon and Magnesium and hence it is also termed as SIMA. The density of the layer is higher than the crust and varies from 3.3 – 5.4g/cm3. The uppermost solid part of the mantle and the entire crust constitute the Lithosphere. The asthenosphere (in between 80-200km) is a highly viscous, mechanically weak and ductile, deforming region of the upper mantle which lies just below the lithosphere. The asthenosphere is the main source of magma and it is the layer over which the lithospheric plates/ continental plates move (plate tectonics). The discontinuity between the upper mantle and the lower mantleis known as Repetti Discontinuity. The portion of the mantle which is just below the lithosphere and asthenosphere, but above the core is called as Mesosphere. Core: o It is the innermost layer surrounding the earth’s centre. o The core is separated from the mantle by Guttenberg’s Discontinuity. o It is composed mainly of iron (Fe) and nickel (Ni) and hence it is also called as NIFE. o The core constitutes nearly 15% of earth’s volume and 32.5% of earth’s mass. o The core is the densest layer of the earth with its density ranges between 9.5-14.5g/cm3. o The Core consists of two sub-layers: the inner core and the outer core. o The inner core is in solid state and the outer core is in the liquid state (or semi-liquid).  o The discontinuity between the upper core and the lower core is called as Lehmann Discontinuity. o Barysphere is sometimes used to refer the core of the earth or sometimes the whole interior. Relative proportion of elements in Crust: O > Si > Al > Fe > Ca > Na > K > Mg Relative proportion of elements in Earth as a whole: Fe > O > Si > Mg > Ni > S > Ca >Al Mantle > Core > Crust (Proportion of Layers) Core>Mantle>Crust(Depth) Core>mantle>Crust(Density) Density of Earth is 5.5 kg/m3 Mechanical Layers of the Earth: The structure of the Earth can also be defined and divided based on how the insides of the planet behavior. Thereby, the mechanical layers correspond to the physical or mechanical properties of these layers. Below are brief overviews of the five mechanical layers of the Earth: Lithosphere: o The lithosphere is the outermost layer of the Earth that consists of the entire crust and the top-most portion of the mantle. o The average thickness is ~70km, but ranges widely: It can be very thin, only a few km thick under oceanic crust or mid-ocean ridges, or very thick, 150+ km under continental crust, particularly mountain belts.  oDepth- 0-100 km o Furthermore, they are divided into pieces called tectonic plates. o The movements of these plates are responsible for mountain-building, oceanic trench formation, earthquakes, and volcanic eruption. Asthenosphere: o The asthenosphere includes the soft layer of the mantle on which the lithosphere moves. o Depth- 100km to 350 km. o It is made of solid silicate materials, but the high temperature allows it to flow on very long timescales. o The lithosphere-asthenosphere boundary is where geophysicists mark the difference in ductility between the two layers. Mesosphere: o The mesosphere is the layer below the asthenosphere but above the outer core. It is essentially the lower mantle. o Average depth-350-2900km o Despite its high temperature, the intense pressure in this region restricts the movements of the molecules of the silicate material despite being under high temperature, thus making it extremely rigid. Outer Core: o The outer core extends from the bottom of the mesosphere or the lower mantle and surrounds the inner core. o Composed of iron and nickel, the extreme temperature allows these metals to remain in their liquid phases. o It is the only layer of the Earth that is a true liquid. o Furthermore, its movement is responsible for generating the magnetic field. Inner Core: o The inner core is also made of iron and some nickel. o However, unlike the outer core, it is a solid ball. o The solidity is due to the intense pressure from the upper layers. o Hence, although it is as hot as the surface of the Sun, there is speculation that the inner core is slowly growing as the liquid outer core at the boundary with the inner core cools and solidifies due to the gradual interior cooling. Temperature, Pressure and Density of the Earth’s Interior Temperature A rise in temperature with increase in depth is observed in mines and deep wells. These evidence along with molten lava erupted from the earth’s interior supports that the temperature increases towards the centre of the earth. The different observations show that the rate of increase of temperature is not uniform from the surface towards the earth’s centre. It is faster at some places and slower at other places.  In the beginning, this rate of increase of temperature is at an average rate of 1 0C for every 32m increase in depth. While in the upper 100kms, the increase in temperature is at the rate of 12 0C per km and in the next 300kms, it is 200C per km. But going further deep, this rate reduces to mere 100C per km. Thus, it is assumed that the rate of increase of temperature beneath the surface is decreasing towards the centre (do not confuse rate of increase of temperature with increase of temperature. Temperature is always increasing from the earth’s surface towards the centre). The temperature at the centre is estimated to lie somewhere between 3000 0C and 50000C, may be that much higher due to the chemical reactions under high-pressure conditions. Even in such a high temperature also, the materials at the centre of the earth are in solid state because of the heavy pressure of the overlying materials. Pressure Just like the temperature, the pressure is also increasing from the surface towards the centre of the earth. It is due to the huge weight of the overlying materials like rocks. It is estimated that in the deeper portions, the pressure is tremendously high which will be nearly 3 to 4 million times more than the pressure of the atmosphere at sea level. At high temperature, the materials beneath will melt towards the centre part of the earth but due to heavy pressure, these molten materials acquire the properties of a solid and are probably in a plastic state. Density Due to increase in pressure and presence of heavier materials like Nickel and Iron towards the centre, the density of earth’s layers also gets on increasing towards the centre. The average density of the layers gets on increasing from crust to core and it is nearly 14.5g/cm3 at the very centre. Biosphere The biosphere is that part of the Earth where living things thrive and live. It is the portion of the planet that can sustain life. The Earth has three other spheres: the atmosphere, the lithosphere, and the hydrosphere. However, not all of them are inhabited by living things. The portions or regions where organisms are found are collectively called the biosphere. Thus, it can also be said that the biosphere is the sum of all the ecosystems on Earth. The biosphere is a term that encompasses all the ecosystems on Earth. It, therefore, includes both non-living elements (like sunlight and water) and living organisms. Biosphere is made of all of the Earths living ecosystems. The Greek words "bios" for "Life" and "sphaira" for the shape of the Earth are the origins of the phrase "biosphere." Thus, biosphere is a narrow zone of the earth where land, water and air interact with each other to support life. It consists of plant and animal kingdom together. It is a global sum of all ecosystems. Characteristics of Biosphere In terms of matter, the biosphere is essentially a closed system with few inputs and outputs. Photosynthesis captures solar energy at a rate of roughly 130 Terawatts per year, making it an open system in terms of energy. It is, however, a self-regulating system that is near to reaching an energetic balance.  Basically, the biosphere is a system that is defined by continual matter cycling and a flow of solar energy, as well as the self-replication of certain big molecules and cells. Water is a crucial predisposing factor because it is necessary for all life to exist. When united as proteins, lipids, carbohydrates, and nucleic acids, the elements carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur offer the building blocks, fuel, and guidance for the creation of life. The production and splitting of phosphate bonds need energy flow to sustain the structure of organisms. Organisms are cellular in nature, with nucleic acids that store and transfer genetic information and always have some sort of surrounding membrane structure. Significance of Biosphere The biosphere is responsible for maintaining the ecosystem that is required for survival. Living organisms are expected to adapt to the climate of the biosphere. Within ecosystems, biodiversity thrives, and the biosphere is a sustainable source of food on Earth. Biodiversity is exactly what it sounds like: a wide range of biological organisms. The biosphere assists in the control of air composition, soil health, and the hydrological (water) cycle as the planet's life support system. CONCEPT OF SUSTAINABILITY AND SUSTAINABLE DEVELOPMENT What is Sustainability? Sustainability means meeting our own needs without compromising the ability of future generations to meet their own needs. In addition to natural resources, we also need social and economic resources. Sustainability is not just environmental- ism. Embedded in most definitions of sustainability we also find concerns for social equity and economic development. Where does the term come from? While the concept of sustainability is a relatively new idea, the movement as a whole has roots in social justice, conservationism, internationalism and other past movements with rich histories. By the end of the twentieth centuries, many of these ideas had come together in the call for ‘sustainable development.’ However, the most common definition was defined by the Brundtland Commission in 1987, released its final report, Our Common Future. It famously defines sustainable development as: “Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs.”  This implies that we need to look after our planet, our resources and our people to ensure that we can live in a sustainable manner. Furthermore, that we can hand down our planet to our children and our grandchildren to live in true sustainability. Why sustainability? The motivations behind sustainability are often complex, personal and diverse. It is unrealistic to create a list of reasons why so many individuals, groups and communities are working towards this goal. Yet, for most people, sustainability comes down to the kind of future we are leaving for the next generation. The Three Pillars of Sustainability We must balance economic, environmental and social factors in equal harmony. This may be illustrated with a sustainability Venn diagram, as shown below: These may be defined as: Environmental Sustainability: Environmental sustainability means that we are living within the means of our natural resources. To live in true environmental sustainability, we need to ensure that we are consuming our natural resources, such as materials, energy fuels, land, water…etc, at a sustainable rate. Some resources are more abundant than others and therefore we need to consider material scarcity, the damage to environment from extraction of these materials and if the resource can be kept within Circular Economy principles. We need to aspire to net zero carbon and then move beyond to ultimately achieve climate positive principles. Environmental sustainability should not be confused with full sustainability, which also need to balance economic and social factors. Economic Sustainability: Economic sustainability requires that a business or country uses its resources efficiently and responsibly so that it can operate in a sustainable manner to consistently produce an operational profit. Without an operational profit a business cannot sustain its activities. Without acting responsibly and using its resources efficiently a company will not be able to sustain its activities in the long term. Social Sustainability: Social sustainability is the ability of society, or any social system, to persistently achieve a good social well-being. Achieving social sustainability ensures that the social well-being of a country, an organisation, or a community can be maintained in the long term. Taking these three pillars of sustainability further if we only achieve two out of three pillars then we end up with: Social + Economic Sustainability = Equitable Social + Environmental Sustainability = Bearable Economic + Environmental Sustainability = Viable Only through balancing economic + social + environmental can we achieve true sustainability. UN Millennium Development Goals (MDGs) At United Nations Millennium Summit (Sep 2000), world leaders agreed to eight specific and measurable development goals—later came to be known as the Millennium Development Goals (MDGs). There were 8 MDGs, 18 targets and 48 indicators to measure the results. The target year was 2015. Millennium Development Goals (MDGs) 1. Eradicate Extreme Hunger and Poverty 2. Achieve Universal Primary Education 3. Promote Gender Equality and Empower Women 4. Reduce Child Mortality 5. Improve Maternal Health 6. Combat HIV/AIDS, Malaria and Other Diseases 7. Ensure Environmental Sustainability 8. Develop a Global Partnership For Development Millennium Development Goals (MDGs) were the eight international development goals for the year 2015. The Millennium Summit of the United Nations in 2000, following the adoption of the United Nations Millennium Declaration. All 191 United Nations member states at that  time, and at least 22 international organizations, committed to helping achieve the Millennium Development Goals by 2015. MDGs set concrete targets and indicators for poverty reduction in order to achieve the rights set forth in the Declaration. MDGs emphasized three areas: human capital, infrastructure and human rights (social, economic and political), with the intent of increasing living standards. There were altogether 8 goals with 21 targets and a series of measurable health indicators and economic indicators for each target. The UN Sustainable Development Goals (SDGs) replaced the Millennium Development Goals (MDGs) in 2015 as a new set of international development goals. Governments have pledged to meet these new goals by 2030. The SDGs offer a new vision, and new challenges, for development actors around the world. The SDGs are wider in scale and in ambition than the MDGs. They consist of 17 goals, 169 targets and 231 unique indicators (established to monitor progress). The SDGs are also different from the MDGs in that they are universal - covering every country in the world - and no longer applicable only to developing countries. ▪ Sustainable Development Goals (SDGs) are the United Nations global development goals. ▪ These are bold universal agreements to end poverty in all its dimensions and craft an equal, just and secure world. ▪ SDG has 17 goals and 169 targets and it covers multiple aspects of growth and development. ▪ It is also known as a successor of MDGs (Millennium Development Goals) ▪ It was adopted by 193 countries of United Nations General Assembly on 25th September 2015  ▪ SDG is officially known as “Transforming our world: the 2030 Agenda for Sustainable Development.” ▪ It is built on the principle agreed upon under resolution, “The Future We Want”. 17 differences between MDGs and SDGs are as follows: Differences Millennium Development Sustainable Development Goals based on Goals Successor or MDGs are predecessor of SDGs are successor to the MDGs. predecessor SDGs. Number of MDGs consists of 8 goals SDGs consists of 17 goals Goals Number of MDG had 21 targets SDG has 169 targets targets Number of MDG had 60 indicators SDG has 232 indicators indicators Formulation of It was produced by a small It was produced by UN Open Working the goals group of technical experts Group (OWG) made up of 30 members representing 70 countries. SDG drafting process also included intense consultation process among: – 193 UN member states – Civil society organizations – Academicians – Scientists – Private sectors and – Other stakeholders all around the world Zero goals – MDG targets for 2015 – The SDGs are designed to finish the were set to get us “halfway” job to get to a statistical “zero” on to the goal of ending hunger hunger, poverty, preventable child and poverty. deaths and other targets. – It had narrow focus on – It has wide focus on poverty reduction poverty reduction. and tries to embed environmental, economic and social aspects together. Applicability – MDGs mainly targeted – SDGs targets and applies uniformly to developing/least developed all the countries; rich, middle income or poor countries. and poor. – It appeals all countries to take action.  – It was designed in the context of “rich donors aiding poor recipients.” Pillars for MDGs ignored the three SDGs have addressed these three pillars sustainable end crucial pillars for more strongly i.e. SDG have ensured of hunger sustainable end of hunger stronger gender roles, people’s i.e. empowering women, participation and government mobilizing everyone, and participation collaborating with local government Focused areas It mainly focused on social It focuses on social inclusion, economic dimensions and better growth, better health and environmental health protection. SDGs also strengthen equity, human rights and non- discrimination Development MDG could not focus SDG focuses holistically on agendas holistically on development. development. It also missed to address root causes of poverty. Scope of work MDG only emphasized on SDG emphasizes on present and the prevalent challenges upcoming challenges Distinguishing Hunger and poverty are SDGs treat the issue of poverty Hunger and combined together in MDG separately from hunger and, food and Poverty. nutrition security Cost MDGs were less costly SDGs are much more costly compared compared to SDG to MDGs Source of MDGs were largely SDGs put sustainable, inclusive funding envisioned to be funded by economic development at the core of the aid flows, which did not strategy materialize Peace Building MDGs did not include SDGs include peace building to the peace building in their core success of ending poverty and hunger. agenda and goals Data Revolution MDGs did not prioritize SDGs target by 2020 to “increase monitoring, evaluation and significantly the availability of high- accountability. quality, timely and reliable data disaggregated by income, gender, age,  race, ethnicity, migratory status, disability, geographic location and other characteristics relevant in national contexts.” Quality The MDGs focused on SDGs focus on the quality of education Education quantity (e.g.: high and the role of education in achieving a enrollment rates) rather more humane world: “education for than quality. This might sustainable development and have declined quality of sustainable lifestyles, human rights, education in many gender equality, promotion of a culture societies. of peace and non-violence, global citizenship, and appreciation of cultural diversity and of culture’s contribution to sustainable development.”