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PAMANTASAN NG LUNGSOD NG MAYNILAUniversity of the City of Manila

College of Engineering and Technology

1 | E n v i r o n m e n t a l a n d E c o l o g i c a l C o n c e p t s

Introduction to Ecology

Man has been interested in ecology in a practical sort of way since early

in his history. In primitive society every individual, to survive, need to have

definite knowledge of his environment, i.e., of the force of nature and of the

plants and animals around him.

Ecology is one of the popular areas of sciences in biology. It is a

pluralistic science in the sense that it depends on a wide variety of methods

and approaches rather than on a limited range of techniques and concepts.

Even if, it is thought as part of biology, one important way in which ecology

differs from most other branches of biology is that it can be properly

appreciated or studied only through a multidisciplinary approach involving

close cooperation from expertise in several disciplines.

The word 'Ecology' was coined from the Greek word 'oikos' meaning

'house' or ' a place to live' to designate the study of organisms in their natural

homes. Specially, it means the study of interactions of Introduction to Ecology

2 organisms with one another and with the physical and chemicalenvironment. The term “logy” is to mean study.

Another way of defining Ecology is to look at the levels of biological

organizations. The molecules of life are organized in specific ways to form cells;

cells are grouped in to tissues; and tissues are arranged to produce functional

organs. The body organs are integrated to produce organ system, and the

entire array of these systems constitutes an organism. Organisms exist not just

as a single individual, but in-groups called population. The various populations

of organisms that interact with one another to form a community;

interdependent communities of organisms interact with the physicalenvironment to compose an ecosystem. Finally, all the ecosystems of the planet

are combined to produce a level of organization known as the biosphere.

Ecology is concerned with the levels of organization beyond that of individual

organism; i.e. population, community, ecosystem, and biosphere.


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A biome involves the linkage of ecosystems into regional classes, which

have similar characteristics. For example, grassland biomes in similar climatic

areas of the world have similar characteristics as pertains to temperature

regimes, rainfall, fire cycles, etc. The smallest biome in the world is the fynbos

biome, which is found only in the southwestern part of South Africa. The biome

concept has not been applied to groupings of ecosystems in aquatic

environments, although it is possible to make such groupings.

Trophic structures

The word trophic means “to feed.” The trophic structure in a community is the

feeding relationships between species. It determines how energy is passed from

organism to organism, like from plants to herbivores to carnivores. The

pyramid is a useful concept to think about how trophic interactions work, but

reality is always more complex. The organisms of the first trophic level are

called producers. They exist at the very bottom of the trophic structure and

they support all other trophic levels. In the marine environment, these are the

phytoplankton (algae). The first trophic level after the producers is the primary

consumer. These organisms are herbivores that eat plants, algae, or bacteria.

The next trophic level is composed of secondary consumers, which include

invertebrates (e.g., crabs) and small fish. The next level is composed of tertiary

consumers, which are larger carnivorous fish and mammals. Detritivores, or

organisms that derive energy from dead material like animal wastes, plant

litter, or dead organisms, fit in at the very bottom of the trophic structure, but

in reality, the food web is far more complex. Consumers at one level can eat at

multiple levels and even the prey of one consumer can eat the eggs and larvae

of their predators.


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THE BIOGEOCHEMICAL CYCLES

A biogeochemical cycle is the complete path a chemical takes through

the four major components, or reservoirs, of Earth’s system: atmosphere ,

hydrosphere (oceans, rivers, lakes, ground waters, and glaciers), lithosphere

(rocks and soils), and biosphere (plants and animals).

A biogeochemical cycle is chemical

because it is chemicals that are cycled,

bio - because the cycle involves life,

and geo - because a cycle may include

atmosphere, water, rocks, and soils.

All living things are made up of chemical elements, but of the more than

103 known chemical elements, only 24 are required by organisms. These 24

are divided into the macronutrients, elements required in large amounts by all

life, and micronutrients, elements required either in small amounts by all life

or in moderate amounts by some forms of life and not at all by others.

The macronutrients in turn include the “big six” elements that are the

fundamental building blocks of life:

Carbon

Hydrogen

Nitrogen

Oxygen

Phosphorus

Sulfur


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Each one plays a special role in organisms. Carbon is the basic building

block of organic compounds; along with oxygen and hydrogen, carbon forms

carbohydrates. Nitrogen, along with these other three, makes proteins.

Phosphorus is the “energy element”— it occurs in compounds called ATP and

ADP, important in the transfer and use of energy within cells.

THE CARBON CYCLE

Carbon is the basic building block of life and the element that anchors

all organic substances, from coal and oil to DNA (deoxyribonucleic acid), the

compound that carries genetic information. Although of central importance to

life, carbon is not one of the most abundant elements in Earth’s crust. It

contributes only 0.032% of the weight of the crust, ranking far behind oxygen


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(45.2%), silicon (29.5%), aluminum (8.0%), iron (5.8%), calcium (5.1%), andmagnesium (2.8%)

Carbon is the fourth most abundant element in the universe, and is

absolutely essential to life on Earth. In fact, carbon constitutes the very

definition of life, as its presence or absence helps define whether a molecule is

considered to be organic or inorganic. Every organism on Earth needs carbon

either for structure, energy, or, as is the case of humans, for both. Discounting

water, you are about half carbon. Additionally, carbon is found in forms as

diverse as the gas carbon dioxide (CO2), and in solids like limestone (CaCO3),

wood, plastic, diamonds, and graphite.

The movement of carbon, in its many forms, between the atmosphere,

oceans, biosphere, and geosphere is described by the carbon cycle. This cycle

consists of several storage carbon reservoirs and the processes by which the

carbon moves between reservoirs. Carbon reservoirs include the atmosphere,

the oceans, vegetation, rocks, and soil.


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It can be useful to think of the carbon cycle in two sets of components:the biological components and the geological components. The biological

components of the carbon cycle are photosynthesis, respiration, and

decomposition by microbes. The geological components of the carbon cycle are

weathering, erosion, subduction, and the formation of fossil fuels.

BIOLOGICAL COMPONENTS

Carbon enters the atmosphere through the respiration of living things.

Virtually all multicellular life on Earth depends on the production of sugars

from sunlight and carbon dioxide (photosynthesis) and the metabolicbreakdown (respiration) of those sugars to produce the energy needed for

movement, growth, and reproduction. Plants take in carbon dioxide (CO2) from

the atmosphere during photosynthesis, and release CO2 back into the

atmosphere during respiration through the following chemical reactions:

Respiration:

C6H12O6 (organic matter) + 6O2 6CO2 + 6 H2O + energy

Photosynthesis:

energy (sunlight) + 6CO2 + H2O C6H12O6 + 6O2

Through photosynthesis, green plants use solar energy to turn

atmospheric carbon dioxide into carbohydrates (sugars). Plants and animals

use these carbohydrates (and other products derived from them) through a

process called respiration, the reverse of photosynthesis. Respiration releases

the energy contained in sugars for use in metabolism and changes

carbohydrate "fuel" back into carbon dioxide, which is in turn released back to

the atmosphere.

On land, the major exchange of carbon with the atmosphere results

from photosynthesis and respiration. During daytime in the growing season,

leaves absorb sunlight and take up carbon dioxide from the atmosphere. At the

same time plants, animals, and soil microbes consume the carbon in organic

matter and return carbon dioxide to the atmosphere. Photosynthesis stops at


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night when the sun cannot provide the driving energy for the reaction, though

respiration continues.

GEOLOGICAL COMPONENTS

Sometimes, plant and animal remains are buried in the earth or sink tothe ocean floor and are protected from microbes. Over hundreds of millions of years animal remains are compressed deeper and deeper into the earth. Tissue

and bone are destroyed but the carbon still remains, having formedcompounds called hydrocarbons, long chains of carbon atoms bound to eachother and to hydrogen atoms. Hydrocarbons are the main component of coaland petroleum .

Humans use fossil fuels to produce heat and electricity, and in doing sothe hydrocarbons in fossil fuels are converted into carbon dioxide and releasedinto the atmosphere. Atmospheric carbon dissolves into the oceans or is taken

up by plants and the cycle continues.

Rock in the earth’s crust is composed of carbon, formed over millions of

years when carbon binds to minerals. Carbon dioxide dissolved in the oceanforms bicarbonate, which combines with calcium to form limestone.

Weathering and erosion wash carbon compounds from rock in theearth’s crust into the ocean. Carbon is also pulled beneath earth’s crust in a

process called subduction and volcanoes, hot springs and geysers spew carbon

dioxide and methane back into the atmosphere.


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THE NITROGEN CYCLE

Nitrogen (N) is an essential component of DNA, RNA, and proteins, the

building blocks of life. All organisms require nitrogen to live and grow.

Although the majority of the air we breathe is N2, most of the nitrogen in the

atmosphere is unavailable for use by organisms. This is because the strong

triple bond between the N atoms in N2 molecules makes it relatively inert, or

unreactive, whereas organisms need reactive nitrogen to be able to incorporate

it into cells. In order for plants and animals to be able to use nitrogen, N2 gas

must first be converted to more a chemically available form such as ammonium

(NH4+), nitrate (NO3-), or organic nitrogen (e.g., urea, which has the formula

(NH2)2CO). The inert nature of N2 means that biologically available nitrogen is

often in short supply in natural ecosystems, limiting plant growth.

The movement of nitrogen between the atmosphere, biosphere, and

geosphere in different forms is called the nitrogen cycle one of the major

biogeochemical cycles. Similar to the carbon cycle, the nitrogen cycle consists

of various reservoirs of nitrogen and processes by which those reservoirs

exchange nitrogen.


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Nitrification

Nitrification is a two-step process in which NH3/ NH4+ is converted to

NO3-. Ammonia is first converted to nitrites (NO2-) and then to nitrates. The

initial step of this process, known as nitritation, involves a type of bacteriacalled nitrosomonas. The chemical equation is:

The second part of the nitrification process is called nitration. Another

soil bacterium, Nitrobacter , oxidizes NO2- to NO3-. These bacteria gain energy

through these conversions, both of which require oxygen to occur. The

chemical equation is:


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Assimilation

Assimilation is the process by which plants and animals incorporate the

NO3- and ammonia formed through nitrogen fixation and nitrification. Plants

take up these forms of nitrogen through their roots, and incorporate them into

plant proteins and nucleic acids. Animals are then able to utilize nitrogen from

the plant tissues.

Ammonification

After nitrogen is incorporated into organic matter, it is often converted

back into inorganic nitrogen by a process called nitrogen mineralization,otherwise known as decay. When organisms die, decomposers (such as

bacteria and fungi) consume the organic matter and lead to the process of

decomposition. During this process, a significant amount of the nitrogen

contained within the dead organism is converted to ammonium. Once in the

form of ammonium, nitrogen is available for use by plants or for further

transformation into nitrate (NO3-) through the process called nitrification.

Organic N NH4+

Denitrification

NO3- N2+ N2O

Through denitrification, oxidized forms of nitrogen such as nitrate (NO3-)

and nitrite (NO2-) are converted to dinitrogen (N2) and, to a lesser extent,

nitrous oxide gas (NO2). Denitrification is an anaerobic process that is carried

out by denitrifying bacteria, which convert nitrate to dinitrogen in the following

sequence:

NO3- NO2- NO N2O N2

Nitric oxide and nitrous oxide are gases that have environmental

impacts. Nitric oxide (NO) contributes to smog, and nitrous oxide (N2O) is an

important greenhouse gas, thereby contributing to global climate change.


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Once converted to dinitrogen, nitrogen is unlikely to be reconverted to a

biologically available form because it is a gas and is rapidly lost to the

atmosphere. Denitrification is the only nitrogen transformation that removes

nitrogen from ecosystems (essentially irreversibly), and it roughly balances the

amount of nitrogen fixed by the nitrogen fixers described above.

THE OXYGEN CYCLE

The biogeochemical cycle that describes about the movement of oxygen

in the atmosphere (air), the biological matter of the ecosystem biosphere (the

global sum of all ecosystems) and the lithosphere (earth's crust). The oxygen

cycle helps the movement of oxygen in the three main regions of the earth, the

atmosphere, biosphere and the lithosphere. It is the circulation of oxygen in

various forms of nature. Oxygen is free in the air and dissolved in water.


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STEPS:

Atmosphere is the region of gases about the surface of the Earth and it isone of the largest reservoirs of free oxygen. Biosphere is the total sum of all

ecosystems and has some free oxygen which is produced by the process of

photosynthesis and other life processes. Lithosphere is the largest reserve of

oxygen. Most of the oxygen in the lithosphere is free moving and is a part of

silicates and oxides of chemical compounds. The oxygen cycle describes about

the free and fixed oxygen of the major spheres.

In the atmosphere Oxygen is freed by the process called photolysis. This

is when high energy sunlight breaks apart oxygen bearing molecules to

produce free oxygen. One of the most well known photolysis it the ozone

cycle. O2 oxygen molecule is broken down to atomic oxygen by the ultra

violet radiation of sunlight. This free oxygen then recombines with

existing O2 molecules to make O3 or ozone. This cycle is important

because it helps to shield the Earth from the majority of harmful ultra

violet radiation turning it to harmless heat before it reaches the Earth’s

surface.

In the biosphere, oxygen undergoes cycles of respiration and

photosynthesis. Humans and animals breathe in oxygen. This oxygen is

used in metabolic processes and carbon dioxide given out. Plants and

phytoplanktons undergo process of photosynthesis where carbon dioxide

is used in the prescence of sunlight to form carbohydrates and oxygen.


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The lithosphere mostly fixes oxygen in minerals such as silicates andoxides. Most of the time the process is automatic all it takes is a pure

form of an element coming in contact with oxygen such as what happens

when iron rusts. A portion of oxygen is freed by chemical weathering.

When a oxygen bearing mineral is exposed to the elements a chemical

reaction occurs that wears it down and in the process produces free

oxygen.

THE SULFUR CYCLE

Sulfur Cycle, circulation of sulfur in various forms through nature.

Sulfur occurs in all living matter as a component of certain amino acids. It is

abundant in the soil in proteins and, through a series of microbial

transformations, ends up as sulfates usable by plants.


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The sulfur cycle contains both atmospheric and terrestrial processes.Within the terrestrial portion, the cycle begins with the weathering of rocks,

releasing the stored sulfur. The sulfur then comes into contact with air where it

is converted into sulfate (SO4). The sulfate is taken up by plants and

microorganisms and is converted into organic forms; animals then consume

these organic forms through foods they eat, thereby moving the sulfur through

the food chain. As organisms die and decompose, some of the sulfur is again

released as a sulfate and some enters the tissues of microorganisms. There are

also a variety of natural sources that emit sulfur directly into the atmosphere,

including volcanic eruptions, the breakdown of organic matter in swamps and

tidal flats, and the evaporation of water.

Sulfur eventually settles back into the Earth or comes down within

rainfall. A continuous loss of sulfur from terrestrial ecosystem runoff occurs

through drainage into lakes and streams, and eventually oceans. Sulfur also

enters the ocean through fallout from the Earth’s atmosphere. Within the

ocean, some sulfur cycles through marine communities, moving through the

food chain. A portion of this sulfur is emitted back into the atmosphere from

sea spray. The remaining sulfur is lost to the ocean depths, combining with

iron to form ferrous sulfide which is responsible for the black color of mostmarine sediments.

THE PHOSPORUS CYCLE

Phosphorus is an important element for all forms of life. As phosphate

(PO4), it makes up an important part of the structural framework that holds

DNA and RNA together. Phosphates are also a critical component of ATP — the

cellular energy carrier — as they serve as an energy release for organisms to use

in building proteins or contacting muscles. Like calcium, phosphorus is

important to vertebrates; in the human body, 80% of phosphorous is found in

teeth and bones.

The phosphorus cycle differs from the other major biogeochemical cycles

in that it does not include a gas phase; although small amounts of phosphoric

acid (H3PO4) may make their way into the atmosphere, contributing — in some

cases — to acid rain. The water, carbon, nitrogen and sulfur cycles all include at

least one phase in which the element is in its gaseous state. Very little


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phosphorus circulates in the atmosphere because at Earth’s normal

temperatures and pressures, phosphorus and its various compounds are not

gases. The largest reservoir of phosphorus is in sedimentary rock.

It is in these rocks where the phosphorus cycle begins. When it rains,

phosphates are removed from the rocks (via weathering) and are distributed

throughout both soils and water. Plants take up the phosphate ions from thesoil. The phosphates then moves from plants to animals when herbivores eat

plants and carnivores eat plants or herbivores. The phosphates absorbed by

animal tissue through consumption eventually returns to the soil through the

excretion of urine and feces, as well as from the final decomposition of plants

and animals after death.

The same process occurs within the aquatic ecosystem. Phosphorus is

not highly soluble, binding tightly to molecules in soil, therefore it mostly

reaches waters by traveling with runoff soil particles. Phosphates also enter

waterways through fertilizer runoff, sewage seepage, natural mineral deposits,and wastes from other industrial processes. These phosphates tend to settle on

ocean floors and lake bottoms. As sediments are stirred up, phosphates may

reenter the phosphorus cycle, but they are more commonly made available to

aquatic organisms by being exposed through erosion. Water plants take up the

waterborne phosphate which then travels up through successive stages of the

aquatic food chain.


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THE HYDROLOGIC CYCLE

The hydrologic cycle involves water moving from the surface (most

importantly the oceans) to the atmosphere, across the land, and everywhere in

between. Environmental scientists know that the hydrologic cycle includes

various processes that change water from solid to liquid to gas form and

transport it to every corner of earth’s surface (and below).

In terms of water, the earth is a closed system, so water isn’t added or

removed from earth; it’s simply transformed, transported, and recycled.


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Water in the oceans moves to the atmosphere through evaporation, aprocess that changes the liquid water to vapor, or gas.

After the water vapor is in the atmosphere, processes of atmospheric circulation transport it around the globe.

As the water vapor is carried over land, the atmosphere often releases itin the form of precipitation (rain or snow).

The precipitation may stay on land in the form of snow (for a year or so)or ice (for many years), or it may move across the land as rivers andstreams, and some of it will evaporate back into the atmosphere.

The water on the surface of the earth may end up in lakes for many years, be absorbed into the soil and rocks and become groundwater, orcontinue to flow as runoff until it reaches the ocean again.

Groundwater is water that flows underground toward the nearest ocean.

Plants release water into the atmosphere through a process calledtranspiration . While plants lose water to the atmosphere pretty much allthe time (sort of like sweating), transpiration is higher duringphotosynthesis, when plants release water into the atmosphere inexchange for taking in carbon dioxide


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Greenhouse gas effect and climate change

Greenhouse Effect: History

Svante Arrhenius (1859-1927) was a Swedish scientist who was the first to

claim in 1896 that fossil fuel combustion may eventually result in enhanced

global warming. He proposed a relation between atmospheric carbon dioxide

concentrations and temperature. He and Thomas Chamberlin calculated that

human activities could warm the earth by adding carbon dioxide to the

atmosphere. This was not actually verified until 1987; in 1988 it was finally

acknowledged that the climate was warmer than any period since 1880. The

greenhouse effect theory was named and the Intergovernmental Panel on

Climate Change (IPCC) was founded by the United Nations Environmental

Programme and the World Meteorological Organization. This organization tries

to predict the impact of the greenhouse effect according to existing climate

models and literature information.

The Enhanced Greenhouse Effect

Some human activities also produce greenhouse gases and these gases

keep increasing in the atmosphere. The change in the balance of the

greenhouse gases has significant effects on the entire planet. Burning fossil

fuels - coal, oil and natural gas - releases carbon dioxide into the atmosphere.

Cutting down and burning trees also produces a lot of carbon dioxide. A group

of greenhouse gases called the chlorofluorocarbons have been used in aerosols,

such as hairspray cans, fridges and in making foam plastics.

Since there are more and more greenhouse gases in the atmosphere,

more heat is trapped, which makes the Earth warmer. This is known as global

warming. A lot of scientists agree that man's activities are making the natural

greenhouse effect stronger. If we carry on polluting the atmosphere with

greenhouse gases, it will have very dangerous effects on the Earth. Today, the

increase in the Earth's temperature is increasing with unprecedented speed.

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To understand just how quickly global warming is accelerating, consider

that during the entire 20th century, the average global temperature increased

by about 0.6 degrees Celsius (slightly more than 1 degree Fahrenheit). Using

computer climate models, scientists estimate that by the year 2100 the average

global temperature will increase by 1.4 degrees to 5.8 degrees Celsius

(approximately 2.5 degrees to 10.5 degrees Fahrenheit).

Greenhouse Gases

Many greenhouse gases occur naturally in the environment, such as

water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Others such

as hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur

hexafluoride (SF6) are created and emitted solely through human activities.

Human activities also add significantly to the level of naturally occurring

greenhouse gases. The principal greenhouse gases that enter the atmosphere

because of human activities are:

Carbon Dioxide (CO2): Carbon dioxide enters the atmosphere through the

burning of fossil fuels (oil, natural gas, and coal), solid waste, trees and woodproducts, and also as a result of other chemical reactions (e.g., manufacture of

cement). Carbon dioxide is also removed from the atmosphere (or

"sequestered") when it is absorbed by plants as part of the biological carbon

cycle.


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Nitrous Oxide (N2O): Nitrous oxide is emitted during various agricultural and

industrial activities, as well as during combustion of fossil fuels and solid

waste.

Methane (CH4): Methane is emitted during the production and transport of

coal, natural gas, and oil. Methane is also emitted when organic waste

decomposes, whether in landfills or in connection with livestock farming.

Fluorinated Gases: Hydrofluorocarbons, perfluorocarbons, and sulfur

hexafluoride are synthetic, powerful greenhouse gases that are emitted from a

variety of industrial processes. Fluorinated gases are sometimes used assubstitutes for ozone-depleting substances (i.e., CFCs, HCFCs, and halons).

These gases are typically emitted in smaller quantities, but because they are

potent greenhouse gases, they are sometimes referred to as High Global

Warming Potential gases ("High GWP gases").

Greenhouse gases vary in their ability to absorb and hold heat in the

atmosphere. HFCs and PFCs are the most heat-absorbent, but there are also

wide differences between naturally occurring gases. For example, nitrous oxide

absorbs 270 times more heat per molecule than carbon dioxide, and methaneabsorbs 21 times more heat per molecule than carbon dioxide. However,

carbon dioxide contributes the most, since its level in the athmosphere is the

highest.

Estimates of future emissions and removals depend in part on

assumptions about changes in underlying human activities. For example, the

demand for fossil fuels such as gasoline and coal is expected to increase greatly

with the predicted growth of the U.S. and global economies.

Many, but not all, human sources of greenhouse gas emissions are expected to

rise in the future. This growth may be reduced by ongoing efforts to increasethe use of newer, cleaner technologies and other measures. Additionally, our

everyday choices about such things as commuting, housing, electricity use,

and recycling can influence the amount of greenhouse gases being emitted.


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The Effects of Global Warming

With more heat trapped on Earth, the planet will become warmer, which

means the weather all over Earth will change. Since the conditions we are

living in are perfect for life, a large rise in temperature could be disastrous for

us and for any other living creatures on Earth. At the moment, it is difficult for

scientists to say how big the changes will be and where the worst effects will

occur. These are some of the assumptions.

The Weather

The effects will vary in different parts of the world: some places willbecome drier and others will become wetter. Although most areas will be

warmer, some areas will become cooler. There may be many storms, floods and

drought, but we do not know which areas of the world will be affected. All over

the world, these weather changes will affect the kinds of crop that can be

grown. Plants, animals, and even people may find it difficult to survive in

different conditions.

Sea Levels

Higher temperatures will make the water of the seas and oceans expand.

Ice melting in the Antarctic and Greenland will flow into the sea. All over the

world, sea levels may rise, perhaps by as much as 20 to 40 cm, by the

beginning of the next century. Higher sea levels will threaten the low-lying

coastal areas of the world, such as the Netherlands and Bangladesh.

Throughout the world, millions of people and areas of land will be at danger

from flooding. Many people will have to leave their homes and large areas of

farmland will be ruined because of floods.

Farming

The changes in the weather will affect the types of crops grown indifferent parts of the world. Some crops, such as wheat and rice, grow better in

higher temperatures, but other plants, such as maize and sugarcane, do not.

Changes in the amount of rainfall will also affect how many plants grow. The

effect of a change in the weather on plant growth may lead to some countries

not having enough food. Brazil, parts of Africa, south-east Asia, and China will

be affected the most and many people could suffer from hunger.


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Plants & Animals

It has taken million of years for life to become used to the conditions on

Earth. As weather and temperature changes, the homes of plants and animals

will be affected all over the world. For example, polar bears and seals will have

to find new land for hunting and living if the ice in the Arctic melts. Many

animals and plants may not be able to cope with these changes and could die.

This could cause the loss of some animal and plant species in certain or all

areas of the world.

People

The changes in climate will affect everyone, but some populations will be

at greater risk. For example, countries whose coastal regions have a largepopulation, such as Egypt and China, may see whole populations move inland

to avoid flood risk areas. The effect on people will depend on how well we can

adapt to the changes and how much we can do to reduce climate change in the

world.

Renewable Energy

There are many forms of renewable energy. Most of these renewable

energies depend in one way or another on sunlight. Wind and hydroelectric

power are the direct result of differential heating of the Earth's surface whichleads to air moving about (wind) and precipitation forming as the air is lifted.

Solar energy is the direct conversion of sunlight using panels or collectors.

Biomass energy is stored sunlight contained in plants. Other renewable

energies that do not depend on sunlight are geothermal energy, which is a

result of radioactive decay in the crust combined with the original heat of

accreting the Earth, and tidal energy, which is a conversion of gravitational

energy.

Solar. This form of energy relies on the nuclear fusion power from the core of

the Sun. This energy can be collected and converted in a few different ways.

The range is from solar water heating with solar collectors or attic cooling with

solar attic fans for domestic use to the complex technologies of direct

conversion of sunlight to electrical energy using mirrors and boilers or

photovoltaic cells. Unfortunately these are currently insufficient to fully power

our modern society.

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Wind Power. The movement of the atmosphere is driven by differences of

temperature at the Earth's surface due to varying temperatures of the Earth's

surface when lit by sunlight. Wind energy can be used to pump water or

generate electricity, but requires extensive areal coverage to produce significant

amounts of energy.

Hydroelectric energy. This form uses the gravitational potential of elevated

water that was lifted from the oceans by sunlight. It is not strictly speaking

renewable since all reservoirs eventually fill up and require very expensive

excavation to become useful again. At this time, most of the available locations

for hydroelectric dams are already used in the developed world.

Biomass is the term for energy from plants. Energy in this form is very

commonly used throughout the world. Unfortunately the most popular is the

burning of trees for cooking and warmth. This process releases copious

amounts of carbon dioxide gases into the atmosphere and is a major

contributor to unhealthy air in many areas. Some of the more modern forms of

biomass energy are methane generation and production of alcohol for

automobile fuel and fuelling electric power plants.

Hydrogen and fuel cells. These are also not strictly renewable energy

resources but are very abundant in availability and are very low in pollution

when utilized. Hydrogen can be burned as a fuel, typically in a vehicle, with

only water as the combustion product. This clean burning fuel can mean a

significant reduction of pollution in cities. Or the hydrogen can be used in fuel

cells, which are similar to batteries, to power an electric motor. In either case

significant production of hydrogen requires abundant power. Due to the need

for energy to produce the initial hydrogen gas, the result is the relocation of

pollution from the cities to the power plants. There are several promising

methods to produce hydrogen, such as solar power, that may alter this picture

drastically.

Geothermal power. Energy left over from the original accretion of the planet

and augmented by heat from radioactive decay seeps out slowly everywhere,

everyday. In certain areas the geothermal gradient (increase in temperature

with depth) is high enough to exploit to generate electricity. This possibility is

limited to a few locations on Earth and many technical problems exist that

limit its utility. Another form of geothermal energy is Earth energy, a result of

http://www.altenergy.org/renewables/wind.htmlhttp://www.altenergy.org/renewables/hydroelectric.htmlhttp://www.altenergy.org/renewables/hydroelectric.htmlhttp://www.altenergy.org/renewables/biomass.htmlhttp://www.altenergy.org/renewables/biomass.htmlhttp://www.altenergy.org/renewables/hydrogen_and_fuel_cells.htmlhttp://www.altenergy.org/renewables/hydrogen_and_fuel_cells.htmlhttp://www.altenergy.org/renewables/geothermal.htmlhttp://www.altenergy.org/renewables/geothermal.htmlhttp://www.altenergy.org/renewables/geothermal.htmlhttp://www.altenergy.org/renewables/hydrogen_and_fuel_cells.htmlhttp://www.altenergy.org/renewables/biomass.htmlhttp://www.altenergy.org/renewables/hydroelectric.htmlhttp://www.altenergy.org/renewables/wind.html


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the heat storage in the Earth's surface. Soil everywhere tends to stay at a

relatively constant temperature, the yearly average, and can be used with heat

pumps to heat a building in winter and cool a building in summer. This form of

energy can lessen the need for other power to maintain comfortable

temperatures in buildings, but cannot be used to produce electricity.

Other forms of energy. Energy from tides, the oceans and hot hydrogen fusion

are other forms that can be used to generate electricity. Each of these is

discussed in some detail with the final result being that each suffers from one

or another significant drawback and cannot be relied upon at this time to solve

the upcoming energy crunch.
http://www.altenergy.org/renewables/other.htmlhttp://www.altenergy.org/renewables/other.htmlhttp://www.altenergy.org/renewables/other.html

envi engg.pdf

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