Free AIOU Solved Assignment Code 1421 Spring 2021

Free AIOU Solved Assignment Code 1421 Spring 2021

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Title Name Introduction to Environment (1421)
University AIOU
Service Type Solved Assignment (Soft copy/PDF)
Course BA
Language ENGLISH
Semester 2021-2021
Assignment Code 1421/2020-2021
Product Assignment of MA 2021-2022 (AIOU)

Course: Introduction to Environment (1421)
Semester: Spring, 2021
ASSIGNMENT No. 1

  1. 1 Define the following terms in your own words.

(i)      Environment

The term ‘environment’ is widely used and has a broad range of definitions, meanings and interpretations. What does the term ‘environment’ mean? In popular usage, for some people, the term ‘environment’ means, simply, ‘nature’: in other words, the natural landscape together with all of its non-human features, characteristics and processes. To those people, the environment is often closely related to notions of wilderness and of pristine landscapes that have not been influenced – or, at least, that have been imperceptibly influenced – by human activities. However, for other people, the term ‘environment’ includes human elements to some extent. Many people would regard agricultural and pastoral landscapes as being part of the environment, whilst others are yet more inclusive and regard all elements of the earth’s surface – including urban areas – as constituting the environment. Thus, in popular usage, the notion of the ‘environment’ is associated with diverse images and is bound up with various assumptions and beliefs that are often unspoken – yet may be strongly held. All of these usages, however, have a central underlying assumption: that the ‘environment’ exists in some kind of relation to humans. Hence the environment is, variously, the ‘backdrop’ to the unfolding narrative of human history, the habitats and resources that humans exploit, the ‘hinterland’ that surrounds human settlements, or the ‘wilderness’ that humans have not yet domesticated or dominated. 

(ii)     Abiotic components

In biology and ecologyabiotic components or abiotic factors are non-living chemical and physical parts of the environment that affect living organisms and the functioning of ecosystems. Abiotic factors and the phenomena associated with them underpin biology as a whole. Abiotic components include physical conditions and non-living resources that affect living organisms in terms of growthmaintenance, and reproduction. Resources are distinguished as substances or objects in the environment required by one organism and consumed or otherwise made unavailable for use by other organisms.

(iii)    Green House Effect

The greenhouse effect is the process by which radiation from a planet’s atmosphere warms the planet’s surface to a temperature above what it would be without this atmosphere. Radiatively active gases (i.e., greenhouse gases) in a planet’s atmosphere radiate energy in all directions. Part of this radiation is directed towards the surface, warming it. The intensity of the downward radiation – that is, the strength of the greenhouse effect – will depend on the atmosphere’s temperature and on the amount of greenhouse gases that the atmosphere contains. Earth’s natural greenhouse effect is critical to supporting life, and initially was a precursor to life moving out of the ocean onto land. Human activities, however, mainly the burning of fossil fuels and clearcutting of forests, have accelerated the greenhouse effect and caused global warming. The planet Venus experienced runaway greenhouse effect, resulting in an atmosphere which is 96% carbon dioxide, with surface atmospheric pressure roughly the same as found 900 m (3,000 ft) underwater on Earth. Venus may have had water oceans, but they would have boiled off as the mean surface temperature rose to the current 735 K (462 °C; 863 °F).                              

(iv)    Exploitation

Exploitation is the act of selfishly taking advantage of someone or a group of people in order to profit from them or otherwise benefit oneself. Exploitation is a noun form of the verb exploit, which commonly means to take advantage in such a way. Examples: Child prostitution, trafficking of children for sexual abuse and exploitation, child pornography, sexual slavery. Economic exploitation of a child: the use of the child in work or other activities for the benefit of others. This includes, but is not limited to, child labour.

(v)     Thermosphere

The thermosphere is the layer in the Earth’s atmosphere directly above the mesosphere and below the exosphere. Within this layer of the atmosphere ultravioletradiation causes photoionization/photodissociation of molecules, creating ions; the thermosphere thus constitutes the larger part of the ionosphere. Taking its name from the Greek θερμός (pronounced thermos) meaning heat, the thermosphere begins at about 80 km (50 mi) above sea level. At these high altitudes, the residual atmospheric gases sort into strata according to molecular mass (see turbosphere). Thermospheric temperatures increase with altitude due to absorption of highly energetic solar radiation. Temperatures are highly dependent on solar activity, and can rise to 1,700 °C (3,100 °F) or more. Radiation causes the atmosphere particles in this layer to become electrically charged particles, enabling radio waves to be refracted and thus be received beyond the horizon. In the exosphere, beginning at about 600 km (375 mi) above sea level, the atmosphere turns into space, although by the judicial criteria set for the definition of the Kármán line, the thermosphere itself is part of space.

(vi)    Ozone layer

The ozone layer or ozone shield is a region of Earth‘s stratosphere that absorbs most of the Sun‘s ultraviolet radiation. It contains a high concentration of ozone (O3) in relation to other parts of the atmosphere, although still small in relation to other gases in the stratosphere. The ozone layer contains less than 10 parts per million of ozone, while the average ozone concentration in Earth’s atmosphere as a whole is about 0.3 parts per million. The ozone layer is mainly found in the lower portion of the stratosphere, from approximately 15 to 35 kilometers (9.3 to 21.7 mi) above Earth, although its thickness varies seasonally and geographically.The ozone layer was discovered in 1913 by the French physicists Charles Fabry and Henri Buisson. Measurements of the sun showed that the radiation sent out from its surface and reaching the ground on Earth is usually consistent with the spectrum of a black body with a temperature in the range of 5,500–6,000 K (5,227 to 5,727 °C), except that there was no radiation below a wavelength of about 310 nm at the ultraviolet end of the spectrum. It was deduced that the missing radiation was being absorbed by something in the atmosphere. Eventually the spectrum of the missing radiation was matched to only one known chemical, ozone. Its properties were explored in detail by the British meteorologist G. M. B. Dobson, who developed a simple spectrophotometer (the Dobsonmeter) that could be used to measure stratospheric ozone from the ground. Between 1928 and 1958, Dobson established a worldwide network of ozone monitoring stations, which continue to operate to this day. The “Dobson unit“, a convenient measure of the amount of ozone overhead, is named in his honor. The ozone layer absorbs 97 to 99 percent of the Sun’s medium-frequency ultraviolet light (from about 200 nm to 315 nm wavelength), which otherwise would potentially damage exposed life forms near the surface.

(vii)   Sustainable development

Sustainable Development is the organizing principle for meeting human development goals while simultaneously sustaining the ability of natural systems to provide the natural resources and ecosystem services on which the economy and society depends. The desired result is a state of society where living conditions and resources are used to continue to meet human needs without undermining the integrity and stability of the natural system. Sustainable development can be defined as development that meets the needs of the present without compromising the ability of future generations to meet their own needs. While the modern concept of sustainable development is yet derived mostly from the 1987 Brundtland Report, it is also rooted in earlier ideas about sustainable forest management and twentieth-century environmental concerns. As the concept developed, it has shifted its focus more towards the economic developmentsocial development and environmental protection for future generations. It has been suggested that “the term ‘sustainability’ should be viewed as humanity’s target goal of human-ecosystem equilibrium, while ‘sustainable development’ refers to the holistic approach and temporal processes that lead us to the end point of sustainability”. Modern economies are endeavoring to reconcile ambitious economic development and obligations of preserving natural resources and ecosystems, as the two are usually seen as of conflicting nature. Instead of holding climate change commitments and other sustainability measures as a remedy to economic development, turning and leveraging them into market opportunities will do greater good. The economic development brought by such organized principles and practices in an economy is called Managed Sustainable Development (MSD).                                    

(viii)  Biosphere

The biosphere, is the worldwide sum of all ecosystems. It can also be termed the zone of life on Earth, a closed system (apart from solar and cosmic radiation and heat from the interior of the Earth), and largely self-regulating. By the most general biophysiological definition, the biosphere is the global ecological system integrating all living beings and their relationships, including their interaction with the elements of the lithospheregeospherehydrosphere, and atmosphere. The biosphere is postulated to have evolved, beginning with a process of biopoiesis (life created naturally from non-living matter, such as simple organic compounds) or biogenesis (life created from living matter), at least some 3.5 billion years ago.

(ix)    Infiltration

Infiltration (hydrology), downward movement of water into soil۔ Infiltration (HVAC), a heating, ventilation, and air conditioning term for air leakage into buildings. Infiltration (medical), the diffusion or accumulation of substances or cells not normal to it or in amounts in excess of the normal. Infiltration/Inflow, leakage of groundwater into sanitary sewers

(x)     Global warming

The rising average temperature of Earth’s climate system, called global warming, is driving changes in rainfall patterns, extreme weather, arrivals of seasons, and more. Collectively, global warming and its effects are known as climate change. While there have been prehistoric periods of global warming, observed changes since the mid-20th century have been unprecedented in rate and scale.The Intergovernmental Panel on Climate Change (IPCC) concluded that “human influence on climate has been the dominant cause of observed warming since the mid-20th century”. These findings have been recognized by the national science academies of major nations and are not disputed by any scientific body of national or international standing. The largest human influence has been the emission of greenhouse gases, with over 90% of the impact from carbon dioxide and methaneFossil fuel burning is the main source of these gases; agricultural emissions and deforestation are also important. Temperature rise is enhanced by self-reinforcing climate feedbacks, such as loss of snow cover, increased water vapour, and melting permafrost.

AIOU Solved Assignment Code 1421 Spring 2021

Q No.2 Write short notes on the following:

  1. i) Scope of Environmental Science and Education

These are some of the many topics that are studied in the field of environmental science. Overall, environmental science is the field of science that studies the interactions of the physical, chemical, and biological components of the environment and also the relationships and effects of these components with the organisms in the environment. The field of environmental science can be divided into three main goals, which are to learn how the natural world works, to understand how we as humans interact with the environment, and also to determine how we affect the environment. The third goal of determining how humans affect the environment also includes finding ways to deal with these effects on the environment.

Interdisciplinary Field

Environmental science is also referred to as an interdisciplinary field because it incorporates information and ideas from multiple disciplines. Within the natural sciences, such fields as biology, chemistry, and geology are included in environmental science. When most people think of environmental science, they think of these natural science aspects, but what makes environmental science such a complex and broad field is that it also includes fields from the social sciences and the humanities.

The social science fields that are incorporated into environmental science include geography, economics, and political science. Philosophy and ethics are the two fields within the humanities that are also included in environmental science. By combining aspects of the natural sciences, social sciences, and the humanities, the field of environmental science can cover more concepts and also examine problems and topics from many different points of view.

Importance of Environmental Science

At this current time, the world around us is changing at a very rapid pace. Some changes are beneficial, but many of the changes are causing damage to our planet. The field of environmental science is a valuable resource for learning more about these changes and how they affect the world we live in.

Let’s examine a major change that is currently occurring and its relationship to environmental science. The large change is the dramatic increase in the number of humans on earth. For most of human history, the population has been less than a million people, but the current population has skyrocketed to over seven billion people. This equals out to seven thousand times more people!

Due to this increase in the human population, there has also been an increase in pressure on the natural resources and ecosystem services that we rely on for survival. Natural resources include a variety of substances and energy sources that we take from the environment and use. Natural resources can be divided into renewable and nonrenewable resources. Renewable natural resources are substances that can be replenished over a period of time, such as sunlight, wind, soil, and timber. On the other hand, nonrenewable natural resources are substances that are in finite supply and will run out. Nonrenewable resources include minerals and crude oils.

Due to the increase in the human population, natural resources are being used up at a more rapid rate than in the past. Although renewable natural resources can be replenished, when they are used too rapidly, they cannot be replenished fast enough to meet human demand. Even worse, when nonrenewable natural resources are used too rapidly, they become closer to running out completely and being gone forever.

Natural resources have been referred to as the ‘merchandise’ produced by the environment, and in this respect, ecosystem services are the ‘facilities’ that we rely on to help produce the merchandise. Ecosystem services are the environment’s natural processes that provide us with the resources we need to support life. Common ecosystem services include water and air purification, nutrient cycling, climate regulation, pollinating of plants, and the recycling of waste. Just like some natural resources, ecosystem services are also limited and can be used up if not regulated.

Now, let’s tie it together and think about population growth and its influence on both natural resources and ecosystem services. As the human population increases and natural resources and ecosystem services are used rapidly and potentially degraded, the future of humans on earth is in jeopardy. This is one major example of why environmental science is important and valuable.

  1. ii) Ecological Pyramid

An ecological pyramid is a graphical representation of the relationship between the different living organisms at different trophic levels. It was given by G.Evylen Hutchinson and Raymond Lindeman.

It can be observed that these pyramids are in the shape of actual pyramids with the base being the broadest, which is covered by the lowest trophic level, i.e., producers. The next level is occupied by the next trophic level, i.e., the primary consumers and so on.

All the calculations for construction of these types of ecological pyramids must take into account all the organisms in a particular trophic level because a sample space of a few numbers or a few species will end up giving a huge level of errors.

Types of Ecological Pyramid

Three types of ecological pyramid exist. They are as follows:

Pyramid of Numbers

Pyramid of Numbers

In this type of ecological pyramid, the number of organisms in each trophic level is considered as a level in the pyramid. The pyramid of numbers is usually upright except for some situations like that of the detritus food chain, where many organisms feed on one dead plant or animal.

Pyramid of Biomass

Pyramid of Biomass

In this particular type of ecological pyramid, each level takes into account the amount of biomass produced by each trophic level. The pyramid of biomass is also upright except for that observed in oceans where large numbers of zooplanktons depend on a relatively smaller number of phytoplanktons.

Pyramid of Energy

Pyramid of Energy

Pyramid of energy is the only type of ecological pyramid, which is always upright as the energy flow in a food chain is always unidirectional. Also, with every increasing trophic level, some energy is lost into the environment.

Importance of Ecological Pyramid

The importance of ecological pyramid can be explained in the following points:

  1. They show the feeding of different organisms in different ecosystems.
  2. It shows the efficiency of energy transfer.
  3. The condition of the ecosystem can be monitored, and any further damage can be prevented.

Limitations of the Ecological Pyramid

  1. More than one species may occupy multiple trophic levels as in case of the food web. Thus, this system does not take into account food webs.
  2. The saprophytes are not considered in any of the pyramids even though they form an important part of the various ecosystem.
  3. These pyramids are applicable only to simple food chains, which usually do not occur naturally.
  4. These pyramids do not deliver any concept in relation to variations in season and climate.
  5. They do not consider the possibility of the existence of the same species at different levels.

iii)     Productivity of ecosystem

In ecology, productivity refers to the rate of formation of biomass in the ecosystem. It can also be referred to as the energy accumulated in the plants by photosynthesis. There are two types of productivity, namely:

  1. Primary Productivity
  2. Secondary Productivity

Primary Productivity

Primary Productivity refers to the generation of biomass from autotrophic organisms such as plants. Photosynthesis is the primary tool for the creation of organic material from inorganic compounds such as carbon dioxide and water. Primary productivity can be divided into two aspects:

  • Gross primary productivity
  • Net primary productivity

Gross primary productivity

The solar energy trapped by the photosynthetic organism is called gross primary productivity. All the organic matters produced falls under gross primary productivity. This depends upon the photosynthetic activity and environmental factors.

Net primary productivity

This is estimated by the gross productivity minus energy lost in respiration.

NPP = GPP – Energy lost by respiration

It the net energy stored in the plants. This energy serves as food for the animals that feed on plants. It is measured as the amount of organic matter produced in a community in a given time. Annually, over 170 billion tons of net primary productivity occurs over the entire biosphere.

Secondary Productivity

Heterotrophs such as animals influence Secondary Productivity. It is the accumulation of energy at the consumer’s level. It keeps moving from one organism to another, unlike primary productivity. This process occurs as a result of organic materials being transferred between various trophic levels. It is also referred to as the rate of increase in the biomass of heterotrophs. Organisms such as animals, fungi, bacteria and numerous protists influence Secondary Production.

Unit of Productivity

Typically, productivity is expressed in units of mass per unit volume (or surface) per unit time.

For more information on Productivity in Ecosystem, keep visiting BYJU’S Biology website. You can also download BYJU’S app for further reference.

  1. iv) Structure off atmosphere

The structure of the atmosphere is represented in a pictorial form below:

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

  • Troposphere
  • Stratosphere
  • Mesosphere
  • Thermosphere
  • Exosphere

This is an important topic in the Geography syllabus for UPSC 2021 Exam.

Troposphere

  • It is considered as the lowest layer of Earth’s atmosphere.
  • The troposphere starts at the surface of the earth and goes up to a height of 7 to 20 km.
  • All-weather occurs within this layer.
  • This layer has water vapor and mature particles.
  • Temperature decreases at the rate of 1 degree Celsius for every 165 m of height.
  • Tropopause separates Troposphere and Stratosphere.

Stratosphere

  • It is the second layer of the atmosphere found above the troposphere.
  • It extends up to 50 km of height.
  • This layer is very dry as it contains little water vapour.
  • This layer provides some advantages for flight because it is above stormy weather and has steady, strong, horizontal winds.
  • The ozone layer is found in this layer.
  • The ozone layer absorbs UV rays and safeguards earth from harmful radiation.
  • Stratopause separates Stratosphere and Mesosphere.

Mesosphere

  • The Mesosphere is found above the stratosphere.
  • It is the coldest of the atmospheric layers.
  • The mesosphere starts at 50 km above the surface of Earth and goes up to 85 km.
  • The temperature drops with altitude in this layer.
  • By 80 km it reaches -100 degrees Celsius.
  • Meteors burn up in this layer.
  • The upper limit is called Mesopause which separates Mesosphere and Thermosphere.

Thermosphere

  • This layer is found above Mesopause from 80 to 400 km.
  • Radio waves that are transmitted from the earth are reflected by this layer.
  • The temperature increases with height.
  • Aurora and satellites occur in this layer.

Ionosphere

  • The lower Thermosphere is called the Ionosphere.
  • The ionosphere consists of electrically charged particles known as ions.
  • This layer is defined as the layer of the atmosphere of Earth that is ionized by cosmic and solar radiation.
  • It is positioned between 80 and 400 km above the Mesopause.

Exosphere

  • It is the outermost layer of the atmosphere.
  • The zone where molecules and atoms escape into space is mentioned as the exosphere.
  • It extends from the top of the thermosphere up to 10,000 km.

AIOU Solved Assignment 1 Code 1421 Spring 2021

Q No.3 What are the levels of organization in nature? Discuss any four of them in detail.

Organization of nature.

That’s a huge answer and I’ll try and answer it briefly and simply. For further clarifications kindly search for the topics. Nature is defined as the phenomenon occuring in the physical world. Now what does that mean? It means the world that we observe with our senses. Science proceeds to observe and explain the said world and phenomenon occurring in nature. So the first level of organization that nature can be categorized is as follows:

  1. Physics – the study of physical phenomenon occuring in the observable universe (it started out as such) and determining the laws that govern said phenomenon .e.g. the Newtonian laws of motion, the universal law of gravitation. Essentially physics studies the interaction of matter in the universe. It’s organisational structure stretches from the smallest particles (the most famous being the higgs boson) that make up matter to the study of stars and heavenly bodies. Mathematics is the language of this elegant field.
  2. Chemistry – The study of elements that make up the physical world. The periodic table is the mainstay for this field. Essentially, the conditions for interaction of elements to form molecules, compounds etc are studied in chemistry. The energy changes involved, the natural occurence of elements, their properties or chemical nature is described in this field. It’s organisational structure encompasses atomic interactions to molecular reactions. It is related to physics as it studies the various physical properties of the environment on elements , molecules and compounds. E.g. electrochemistry studies the role of electricity and it’s related chemical reactions. Mathematics is used extensively in this field, however unlike physics, it’s role is less in this field.
  3. Biology – The study of the biotic component or life in the universe. It also incorporates the abiotic conditions of the physical and chemical world that are necessary for life to exist. This field seems (until life is confirmed on other planets) restricted to the 3rd planet of our solar system. It’s organisational structure starts from the basic unit of life, which is a single cell, to ecosystems and planetary biomes which include populations of different species interacting with each other and playing out the phenomenon of life. Biology leans heavily on chemistry as most of the reactions that sustain life are chemically driven. Additionally, the study of physics plays an important part in influencing the adaptation of life to the abiotic part of nature. It’s used extensively in exobiology to study for the evidence of life outside this planet. Mathematics plays an integral part, however, like chemistry it’s role is more of a facilitator to understand the subject. Practically, Statistics is used more often than any other branch of mathematics in this diverse field. Therefore to sum up, the organisational structure of nature starts from the smallest known physical particles like higgs boson to the single biggest entity that makes up nature – our observable universe that includes billions of galaxies with billions of stars with billions of planets. Yet do we share only this planet with other species?slightly left of the middle of our spiral galaxy.. the Fermi paradox really does boggle the mind. Nature can be studied at small levels or at large levels. The levels of organization are described below from the smallest to the largest:
  • SPECIES – A species is a group of individuals that are genetically related and can breed to produce fertile young. Individuals are not members of the same species if their members cannot produce offspring that can also have children. The second word in the two word name given to every organism is the species name. For example, in Homo sapiens, sapiens is the species name.
  • POPULATION – A population is a group of organisms belonging to the same species that live in the same area and interact with one another.
  • COMMUNITY – A community is all of the populations of different species that live in the same area and interact with one another. A community is composed of all of the biotic factors of an area.
  • ECOSYSTEM – An ecosystemincludes the living organisms (all the populations) in an area and the non-living aspects of the environment . An ecosystem is made of the biotic and abiotic factors in an area.
  • BIOSPHERE – The biosphere is the part of the planet with living organisms . The biosphere includes most of Earth, including part of the oceans and the atmosphere.

AIOU Solved Assignment 2 Code 1421 Spring 2021

Q No.4 (a)     What are the sources of green house gases? Write down any two methods which contribute to control global warning.                                                                                                         

Behind the struggle to address global warming and climate change lies the increase in greenhouse gases in our atmosphere. A greenhouse gas is any gaseous compound in the atmosphere that is capable of absorbing infrared radiation, thereby trapping and holding heat in the atmosphere. By increasing the heat in the atmosphere, greenhouse gases are responsible for the greenhouse effect, which ultimately leads to global warming.

Solar radiation and the “greenhouse effect”

Global warming isn’t a new concept in science. The basics of the phenomenon were worked out well over a century ago by Svante Arrhenius in 1896. His paper, published in the Philosophical Magazine and Journal of Science, was the first to quantify the contribution of carbon dioxide to what scientists now call the “greenhouse effect.”

The greenhouse effect occurs because the sun bombards Earth with enormous amounts of radiation, which strike Earth’s atmosphere in the form of visible light, plus ultraviolet (UV), infrared (IR) and other types of radiation that are invisible to the human eye. About 30 percent of the radiation striking the Earth is reflected back out to space by clouds, ice and other reflective surfaces. The remaining 70 percent is absorbed by the oceans, the land and the atmosphere, according to NASA.

As they absorb radiation and heat up, the oceans, land and atmosphere release heat in the form of IR thermal radiation, which passes out of the atmosphere into space. The balance between incoming and outgoing radiation keeps Earth’s overall average temperature at about 59 degrees Fahrenheit (15 degrees Celsius), according to NASA.

This exchange of incoming and outgoing radiation that warms Earth is referred to as the greenhouse effect because a greenhouse works in much the same way. Incoming UV radiation easily passes through the glass walls of a greenhouse and is absorbed by the plants and hard surfaces inside. Weaker IR radiation, however, has difficulty passing out through the glass walls and is trapped inside, warming the greenhouse.

How greenhouse gases affect global warming

The gases in the atmosphere that absorb radiation are known as “greenhouse gases” (sometimes abbreviated as GHG) because they are largely responsible for the greenhouse effect. The greenhouse effect, in turn, is one of the leading causes of global warming. The most significant greenhouse gases are water vapor (H2O), carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), according to the Environmental Protection Agency (EPA). “While oxygen (O2) is the second most abundant gas in our atmosphere, O2 does not absorb thermal infrared radiation,” said Michael Daley, an associate professor of environmental science at Lasell College in Massachusetts.

While some argue that global warming is a natural process and that there have always been greenhouse gases, the amount of gases in the atmosphere has skyrocketed in recent history. Before the Industrial Revolution, atmospheric CO2 fluctuated between about 180 parts per million (ppm) during ice ages and 280 ppm during interglacial warm periods. Since the Industrial Revolution, though, the amount of CO2 has increased 100 times faster than the increase when the last ice age ended, according to the National Oceanic and Atmospheric Administration (NOAA).

Fluorinated gases — that is, gases to which the element fluorine was added — including hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride, are created during industrial processes and are also considered greenhouse gases. Though they are present in very small concentrations, they trap heat very effectively, making them high “global-warming potential” (GWP) gases.

Chlorofluorocarbons (CFCs), once used as refrigerants and aerosol propellants until they were phased out by international agreement, are also greenhouse gases.

There are three factors affect the degree to which any greenhouse gas will influence global warming, as follows:

  • Its abundance in the atmosphere.
  • How long it stays in the atmosphere.
  • Its global-warming potential.

Carbon dioxide has a significant impact on global warming partly because of its abundance in the atmosphere. According to the EPA, in 2016, U.S. greenhouse gas emissions totaled 6,511 million metric tons (7,177 million tons) of carbon dioxide equivalents, which equaled 81 percent of all human-caused greenhouse gases — down 2.5 percent from the year before. Additionally, CO2 stays in the atmosphere for thousands of years.

However, methane is about 21 times more efficient at absorbing radiation than CO2, giving it a higher GWP rating, even though it stays in the atmosphere only about 10 years, according to the EPA.

Sources of greenhouse gases

Some greenhouse gases, like methane, are produced through agricultural practices, including livestock manure. Others, like CO2, largely result from natural processes like respiration and from the burning of fossil fuels like coal, oil and gas.

The second cause of CO2 release is deforestation, according to research published by Duke University. When trees are killed to produce goods or heat, they release the carbon that is normally stored for photosynthesis. This process releases nearly a billion tons of carbon into the atmosphere per year, according to the 2010 Global Forest Resources Assessment.

Forestry and other land-use practices can offset some of these greenhouse gas emissions, according to the EPA.

“Replanting helps to reduce the buildup of carbon dioxide in the atmosphere as growing trees sequester carbon dioxide through photosynthesis,” Daley told Live Science. “However, forests cannot sequester all of the carbon dioxide we are emitting to the atmosphere through the burning of fossil fuels, and a reduction in fossil fuel emissions is still necessary to avoid build up in the atmosphere.”

Worldwide, the output of greenhouse gases is a source of grave concern. From the time the Industrial Revolution began to the year 2009, atmospheric CO2 levels have increased almost 38 percent and methane levels have increased a whopping 148 percent, according to NASA, and most of that increase has been in the past 50 years. Because of global warming, 2016 was the warmest year on record, and with 2018 on track to be the fourth warmest, 20 of the hottest years on record have all come after 1998, according to the World Meteorological Organization.

“The warming we observe affects atmospheric circulation, which impacts rainfall patterns globally,” said Josef Werne, an associate professor in the Department of Geology and Planetary Science at the University of Pittsburgh. “This will lead to big environmental changes, and challenges, for people all across the globe.”

Our planet’s future

If current trends continue, scientists, government officials and a growing number of citizens fear that the worst effects of global warming — extreme weather, rising sea levels, plant and animal extinctions, ocean acidification, major shifts in climate and unprecedented social upheaval — will be inevitable.

In answer to the problems caused by global warming by greenhouse gases, the U.S. government created a climate action plan in 2013. And in April 2016, representatives from 73 countries signed the Paris Agreement, an international pact to combat climate change by investing in a sustainable, low-carbon future, according to the United Nations Framework Convention on Climate Change (UNFCCC). The U.S. was included among the countries that agreed to the accord in 2016, but began proceedings to withdraw from the Paris Agreement in June 2017.

According to the EPA, greenhouse gas emissions were 12 percent lower in 2016 than in 2005, in part due to the large decrease in fossil fuel combustion resulting from the switch to natural gas from coal. The warmer winter conditions during those years also reduced the need for many homes and businesses to turn up the heat.

Researchers around the world continue to work toward finding ways to lower greenhouse gas emissions and mitigate their effects. One potential solution scientists are examining is to suck the carbon dioxide out of the atmosphere and bury it underground indefinitely, said Dina Leech, an associate professor of biological and environmental sciences at Longwood University in Virginia.

(b)    Differentiate between the following:                                                             

  1. i) Browsing and Grazing

Grazing refers to the process of animals feeding on the vegetation that grows near the ground such as grass and any other low-growing vegetation. Examples of grazers include sheep, zebra, rabbit, cattle, giant panda, horses, wildebeests, and capybara. Grazers keep plants from growing too much to prevent them from blocking other plants from getting sunlight that is necessary for photosynthesis. An exercise of caution is important in grazing to avoid overgrazing which may result in erosion and desertification.

On the other hand, browsing is the type of feeding whereby herbivores eat high-growing plants such as leaves, the bark of trees, and shrubs among others. Examples of browsers are white-tailed deer, goats, giraffe, Siberian ibex, alpine ibex, and Sulaiman markhor deer, among others. One advantage of the browsers is that they cannot die of hunger during snowy seasons as they can access their food; unlike in the case of grazers where the vegetation may be covered in snow. On the other hand, some grazers may be disadvantaged when the plants grow too tall such that they become inaccessible.

First, grazing relates to the process of animals feeding on low-growing vegetation whereas browsing refers to the process of animals feeding on high-growing plants. Secondly, grazers and browsers are adapted differently for their feeding habits. For instance, grazers have a smaller true stomach compared to the browsers. Additionally, the mouths of the grazers are small and have stiffer lips compared to the browsers whose mouths are wider and have long tongues to reach the high-growing plants.

  1. ii) Major and Trace gases

Trace gases are those gases in the atmosphere other than nitrogen (78.1%), oxygen (20.9%), and argon (0.934%) which, in combination, make up 99.934% of the gases in the atmosphere (not including water vapor).

Multiple gases contribute to the greenhouse effect that sets Earth’s temperature over geologic time. Small changes in the atmospheric concentration of these gases can lead to changes in temperature that make the difference between ice ages when mastodons roamed the Earth, and the sweltering heat in which the dinosaurs lived.

Two characteristics of atmospheric gases determine the strength of their greenhouse effect.

The first is their ability to absorb energy and radiate it (their “radiative efficiency”).  The second is the atmospheric lifetime, which measures how long the gas stays in the atmosphere before natural processes (e.g., chemical reactions) remove it.

These characteristics are incorporated in the Global Warming Potential (GWP), a measure of the radiative effect (i.e. the strength of their greenhouse effect) of each unit of gas (by weight) over a specified period of time, expressed relative to the radiative effect of carbon dioxide (CO2). This is often calculated over 100 years, though it can be done for any time period. Gases with high GWPs will warm the Earth more than an equal amount of CO2 over the same time period. A gas with a long lifetime, but relatively low radiative efficiency, may end up exerting more warming influence than a gas that leaves the atmosphere faster than the time window of interest but has a comparatively high radiative efficiency, and this would be reflected in a higher GWP.

iii)     Lava and rocks

The slower cooling of this coarser rock creates more air pockets within the rock and these cause problems, such as cracking, when you heat the stone directly, which is why you can’t avoid cracks with any products using granite, which are popular with one company in particular, Black Rock Grill.

Extrusive igneous rocks are formed by the cooling of molten magma above the Earth’s surface. Lava is the name given to molten rock expelled by a volcano during an eruption, and the resulting rock after solidification and cooling, and this formation cools and solidifies much quicker than intrusive igneous rocks.

The quicker cooling forms rocks that are smooth and fine grained and we use these rocks to create STEAKSTONES. The super tight bonding of the minerals creates an extremely strong and dense product, and one that allows us to guarantee that it will never crack under normal use.

The difference between Rock and Stone and is that Rock refers to raw material in situ whilst Stone depicts human intervention. Basically all stones have been rock at some point, but not all rocks become stones. They’re a bit more special.

  1. iv) Intrusive and extrusive rocks

Igneous rocks are called intrusive when they cool and solidify beneath the surface. Intrusive rocks form plutons and so are also called plutonic. A pluton is an igneous intrusive rock body that has cooled in the crust. When magma cools within the Earth, the cooling proceeds slowly. Slow cooling allows time for large crystals to form, so intrusive igneous rocks have visible crystals. Granite is the most common intrusive igneous rock.

Igneous rocks make up most of the rocks on Earth. Most igneous rocks are buried below the surface and covered with sedimentary rock, or are buried beneath the ocean water. In some places, geological processes have brought igneous rocks to the surface.

Igneous rocks are called extrusive when they cool and solidify above the surface. These rocks usually form from a volcano, so they are also called volcanic rocks.

Extrusive igneous rocks cool much more rapidly than intrusive rocks. There is little time for crystals to form, so extrusive igneous rocks have tiny crystals.

Some volcanic rocks have a different texture. The rock has large crystals set within a matrix of tiny crystals. In this case, the magma cooled enough to form some crystals before erupting. Once erupted, the rest of the lava cooled rapidly. This is called porphyritic texture.

Cooling rate and gas content create other textures. Lavas that cool extremely rapidly may have a glassy texture. Those with many holes from gas bubbles have a vesicular texture.

  1. v) Convergent and divergent boundries
  • Divergent boundariesare areas where plates move away from each other, forming either mid-oceanic ridges or rift valleys. These are also known as constructive boundaries.
  • Convergent boundariesare areas where plates move toward each other and collide. These are also known as compressional or destructive boundaries.
    • Subductionzones occur where an oceanic plate meets a continental plate and is pushed underneath it. Subduction zones are marked by oceanic trenches. The descending end of the oceanic plate melts and creates pressure in the mantle, causing volcanoes to form.
    • Obductionoccurs when the continental plate is pushed under the oceanic plate, but this is unusual as the relative densities of the tectonic plates favours subduction of the oceanic plate. This causes the oceanic plate to buckle and usually results in a new mid-ocean ridge forming and turning the obduction into subduction.[citation needed]
    • Orogenic beltsoccur where two continental plates collide and push upwards to form large mountain ranges. These are also known as collision boundaries.
  • Transform boundariesoccur when two plates grind past each other with only limited convergent or divergent activity.

AIOU Solved Assignment Code 1421 Autumn 2021

Q No.5 Explain different types or erosions and its impacts on environment. Give an account about erosion in Pakistan.

Soil is the earth’s fragile skin that anchors all life on Earth. It is comprised of countless species that create a dynamic and complex ecosystem and is among the most precious resources to humans. Increased demand for agriculture commodities generates incentives to convert forests and grasslands to farm fields and pastures. The transition to agriculture from natural vegetation often cannot hold onto the soil and many of these plants, such as coffee, cotton, palm oil, soybean and wheat, can actually increase soil erosion beyond the soil’s ability to maintain itself.

Half of the topsoil on the planet has been lost in the last 150 years. In addition to erosion, soil quality is affected by other aspects of agriculture. These impacts include compaction, loss of soil structure, nutrient degradation, and soil salinity. These are very real and at times severe issues.

The effects of soil erosion go beyond the loss of fertile land. It has led to increased pollution and sedimentation in streams and rivers, clogging these waterways and causing declines in fish and other species. And degraded lands are also often less able to hold onto water, which can worsen flooding. Sustainable land use can help to reduce the impacts of agriculture and livestock, preventing soil degradation and erosion and the loss of valuable land to desertification.

The health of soil is a primary concern to farmers and the global community whose livelihoods depend on well managed agriculture that starts with the dirt beneath our feet. While there are many challenges to maintaining healthy soil, there are also solutions and a dedicated group of people, including WWF, who work to innovate and maintain the fragile skin from which biodiversity springs.

As the human population has expanded, more and more land has been cleared for agriculture and other pursuits that degrade the soil and make erosion more likely to occur.

AGRICULTURE

When agriculture fields replace natural vegetation, topsoil is exposed and can dry out. The diversity and quantity of microorganisms that help to keep the soil fertile can decrease, and nutrients may wash out. Soil can be blown away by the winds or washed away by rains.

DEFORESTATION

Without plant cover, erosion can occur and sweep the land into rivers. The agricultural plants that often replace the trees cannot hold onto the soil and many of these plants, such as coffee, cotton, palm oil, soybean and wheat, can actually worsen soil erosion. And as land loses its fertile soil, agricultural producers move on, clear more forest and continue the cycle of soil loss.

OVERGRAZING

The conversion of natural ecosystems to pasture land doesn’t damage the land initially as much as crop production, but this change in usage can lead to high rates of erosion and loss of topsoil and nutrients. Overgrazing can reduce ground cover, enabling erosion and compaction of the land by wind and rain.. This reduces the ability for plants to grow and water to penetrate, which harms soil microbes and results in serious erosion of the land.

USE OF AGROCHEMICALS

Pesticides and other chemicals used on crop plants have helped farmers to increase yields. Scientists have found that overuse of some of these chemicals changes soil composition and disrupts the balance of microorganisms in the soil. This stimulates the growth of harmful bacteria at the expense of beneficial kinds.

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