Chapter 4; global atmosphere change

CHAPTER 4: Global Atmosphere Change

Prepared by: Shaheen SardarBSc textile engineeringMS Textile ManagementFaisalabad, Punjab, PakistanEmail: [email protected]

COURSE TITLE: Environmental issues of textile industry

THE ATMOSPHERE OF THE EARTH• The atmosphere is made up almost entirely of

Nitrogen and Oxygen, other gases and particles existing in very small concentrations determine to a large extent the habitability of the earth.

• These other gases are CO2, Nitrous oxide (N2O), Methane (CH4), and Ozone (O3) as well as a category of human made gases called “halocarbons” that includes chlorofluorocarbons (CFCs), hydro-chlorofluorocarbons (HCFCs), hydro-fluorocarbons (HFCs), carbon tetrachloride (CCl4), methyl-chloroform (CH3 CCl3), and halons.

THE ATMOSPHERE OF THE EARTH

• Concentrations of most of the gases are essentially unchanging. But CO2, CH4, and N2O are rising.

• Following is the composition of clean, Dry air (fraction by volume in troposphere, 1994)

Constituent FormulaPercent by

volume

Parts per

million (ppm)

Nitrogen N2 78.08 780,800

Oxygen O2 20.95 209,500

Argon Ar 0.93 9300

Carbon dioxide CO2 0.035 358

Neon Ne 0.0018 18

Helium He 0.0005 5.2

Methane CH4 0.00017 1.7

Krypton Kr 0.00011 1.1

Nitrous oxide N2O 0.00003 0.3

Hydrogen H2 0.00005 0.5

Ozone O3 0.000004 0.04

THE ATMOSPHERE OF THE EARTH

LAYERS OF EARTH:• According to temperature, earth’s four layers

are troposphere, stratosphere, mesosphere, and thermosphere. These layers are described below.

LAYERS OF EARTH

(1) Troposphere:• The first layer is called the troposphere. The

depth of this layer varies from about 8 to 16 kilometers. Greatest depths occur at the tropics where warm temperatures cause vertical expansion of the lower atmosphere.

Troposphere

• From the tropics to the Earth's Polar Regions the troposphere becomes gradually thinner. The depth of this layer at the poles is roughly half as thick when compared to the tropics. Average depth of the troposphere is approximately 11 kilometers.

Troposphere

• More than 80% of the mass of the atmosphere and all of the water vapor, clouds, and precipitation occur in troposphere. Maximum air temperature also occurs near the Earth's surface in this layer.

Troposphere

• With increasing height, air temperature drops uniformly with altitude at a rate of approximately 6.5° Celsius per 1000 meters. This phenomenon is commonly called the Environmental Lapse Rate. At an average temperature of -56.5° Celsius, the top of the troposphere is reached. At the upper edge of the troposphere is a narrow transition zone known as the tropopause.

LAYERS OF EARTH

(2) Stratosphere:• Stratosphere is a stable layer of very dry air.

Pollutants that find their way into the stratosphere may remain there for many years before they eventually drift back into the troposphere, where they can be more easily diluted and ultimately removed by settling or precipitation.

LAYERS OF EARTH

LAYERS OF EARTH

Stratosphere

• In the Stratosphere short wavelength ultraviolet energy is absorbed by Ozone (O3) oxygen (O2), causing air to be heated.

• Above the tropopause is the stratosphere. This layer extends from an average altitude of 11 to 50 kilometers above the Earth's surface.

Stratosphere

• The stratosphere contains about 19.9 % of the total mass found in the atmosphere. Very little weather occurs in the stratosphere. The troposphere and stratosphere combined account for 99.9% of the mass of the atmosphere.

Stratosphere

• Occasionally, the top portions of thunderstorms breach this layer. The lower portion of the stratosphere is also influenced by the polar jet stream and subtropical jet stream.

• In the first 9 kilometers of the stratosphere, temperature remains constant with height. A zone with constant temperature in the atmosphere is called an isothermal layer.

Stratosphere

• From an altitude of 20 to 50 kilometers, temperature increases with an increase in altitude. The higher temperatures found in this region of the stratosphere occurs because of a localized concentration of ozone gas molecules. These molecules absorb ultraviolet sunlight creating heat energy that warms the stratosphere.

Stratosphere

• Ozone is primarily found in the atmosphere at varying concentrations between the altitudes of 10 to 50 kilometers. This layer of ozone is also called the ozone layer.

• The ozone layer is important to organisms at the Earth's surface as it protects them from the harmful effects of the sun's ultraviolet radiation. Without the ozone layer life could not exist on the Earth's surface.

LAYERS OF EARTH

(3) Mesosphere: • Separating the mesosphere from the

stratosphere is a transition zone called the stratopause.

• In the mesosphere, air mixes fairly readily.• In the mesosphere, the atmosphere reaches

its coldest temperatures (about -90° Celsius) at a height of approximately 80 kilometers.

Mesosphere

• At the top of the mesosphere is another transition zone known as the mesopause.

• The temperature of the atmosphere decreases with altitude, until the Thermosphere is reached.

LAYERS OF EARTH

(4) Thermosphere: • Then, next layer is thermosphere. Heating of

thermosphere is due to the absorption of solar energy by atomic oxygen.

• Thermosphere is exceptionally hot. • The last atmospheric layer has an altitude

greater than 80 kilometers and is called the thermosphere.

Thermosphere

• Temperatures in this layer can be as high as 1200°C. These high temperatures are generated from the absorption of intense solar radiation by oxygen molecules (O2).

• Measuring the temperature of thermosphere with a thermometer is a very difficult process.

GLOBAL TEMPERATURE

• The average global temperature has risen in the past 150 years.

• The period from 1961 to 1990 is the comparison point for this graph. This is represented by the horizontal line at 0. The anomaly, or variation from this average, is shown for each year.

GLOBAL TEMPERATURE

THE GREEN HOUSE EFFECT

• Have you ever been inside a greenhouse? Greenhouses are very warm inside all year round — this is how plants are grown inside them, even in the winter.

• The way a greenhouse works is that the glass allows the sun's rays to shine in, but then prevents the heat from escaping once it is inside.

• Now, think of the Earth as being a giant greenhouse.


• The gases on Earth act just like the glass; this is how the Earth gets warm from the sun even though it is about 93 million miles away.

• The gases allow the sun's rays to shine in, but then prevent the heat from escaping the Earth.



• This way of warming the Earth's surface is referred to as the greenhouse effect.

• Following are the main gases in the Earth's atmosphere that cause the greenhouse effect:

• (1) Water vapor, (2) Carbon dioxide, (3) Methane, (4) Nitrous oxide


THE GREEN HOUSE EFFECT• Although the Earth's atmosphere naturally

contains these greenhouse gases, over the past few decades their presence has increased, causing the temperature of the earth to increase.

THE GREEN HOUSE EFFECT• The following human activities are the biggest

contributors to the increase of greenhouse gases: (1) Burning gasoline to drive cars and trucks.(2) Burning oil, coal or wood to produce electricity

for heating, cooling and other purposes.(3) Burning forests to clear land.

THE GREEN HOUSE EFFECTExperiment:

• Take two jars and put a teaspoon of water in each jar. Put a lid on just one jar. Place both jars in a sunny spot. After a few hours, check on the jars. You'll see that the open jar hasn't changed, but the closed jar will be steamy and hot inside. What happened? The heat from the sun could not escape from the closed jar, just like it can not escape from the Earth's surface.

GLOBAL ENERGY BALANCE

• It is the global radiation balance at the top of the atmosphere and at the earth's surface.

• Part of the total incoming solar energy 340 Watts/ m2 is absorbed by clouds and atmospheric gases and part is reflected by clouds, atmospheric gases and the ground (land and water surfaces).


• Approximately half (170 Watts/ m2) is absorbed by the ground. Some of this energy is re-radiated upward and some transferred to the atmosphere as ‘sensible’ and ‘latent’ heat by turbulence and convection.

• The atmosphere radiates infrared radiation in all directions.


• When balance is achieved in the atmosphere, the total (short wave and long wave) upward radiation from the top of the atmosphere equals the 340 Watts/ m2 received from the sun.


RADIATIVE FORCING OF CLIMATE CHANGE

• Radiative forcing is generally defined as the change in net irradiance between different layers of the atmosphere. (irradiance is the density of radiation incident on a given surface usually expressed in watts per square centimeter or square meter).

• Typically, radiative forcing is quantified at the troposphere in units of watts per square meter.

RADIATIVE FORCING OF CLIMATE CHANGE

• A positive forcing (more incoming energy) tends to warm the system, while a negative forcing (more outgoing energy) tends to cool it.

• Sources of radiative forcing include changes in insolation (incident solar radiation) and in concentrations of radiatively active gases and aerosols.

CARBON DIOXIDE (CO2)

• CO2 Concentrations are now almost 30% higher than they were just before the industrial revolution.

• Carbon Dioxide (CO2) is a colorless, odorless non-flammable gas and is the most prominent Greenhouse gas in Earth's atmosphere.


• It is recycled through the atmosphere by the process photosynthesis, which makes human life possible. Photosynthesis is the process of green plants and other organisms transforming light energy into chemical energy.

• Light Energy is trapped and used to convert carbon dioxide, water, and other minerals into oxygen and energy rich organic compounds.


• Carbon Dioxide is emitted into the air as humans exhale, burn fossil fuels for energy, and deforests the planet.

• Every year humans add over 30 billion tons of carbon dioxide in the atmosphere by these processes, and it is up thirty percent since 1750.


• An isolated test at Mauna Loa in Hawaii revealed more than a 12% (316 ppm in 1959 to 360 ppm in 1996) increase in mean annual concentration of carbon dioxide.

• Mauna Loa, located in Hawaii, is the world’s largest volcano at 40,000 cubic km and 4,170 meters above sea level.

METHANE (CH4)

• CH4 Concentrations are now increasing as a result of human activities.

• Methane is a colorless, odorless, flammable gas.

• It is formed when plants decay and where there is very little air.

• It is often called swamp gas because it is abundant around water and swamps.

METHANE (CH4)• Bacteria that breakdown organic matter in

wetlands and bacteria that are found in cows, sheep, goats, buffalo, termites, and camels produce methane naturally.

• Since 1750, methane has doubled, and could double again by 2050. Each year we add 350-500 million tons of methane to the air by raising livestock, coal mining, drilling for oil and natural gas, rice cultivation, and garbage sitting in landfills.

• It stays in the atmosphere for only 10 years, but traps 20 times more heat than carbon dioxide.

METHANE (CH4)

Land fills; 11%

Domestic Sewage; 7%

Animal waste; 7%

Fossil fuels; 26%

Enteric fermenta-tion; 22%

Rice Paddies; 16%

Biomass burning; 11%

NITROUS OXIDE (N20): (LAUGHING GAS)

• (N20) Concentrations are now increasing as a result of human activities.

• It is released into the atmosphere mostly during the nitrification portion of the nitrogen cycle.; NH+

4 → N2 →N2O → NO–2 → NO–

3

• Natural sources are oceans and wet forest soils.• Anthropogenic emissions are the result of

tropical agriculture.


• Other sources include combustion of fuels containing nitrogen, and a variety of industrial processes such as the production of nylon.

• Nitrous oxide is another colorless greenhouse gas; however, it has a sweet odor. It is primarily used as an anesthetic because it deadens pain and for this characteristic is called laughing gas.

• This gas is released naturally from oceans and by bacteria in soils.


• Nitrous oxide gas raised by more than 15% since 1750.

• Each year we add 7-13 million tons into the atmosphere by using nitrogen based fertilizers, disposing of human and animal waste in sewage treatment plants, automobile exhaust, and other sources not yet identified.

• It is important to reduce emissions because the nitrous oxide we release today will still be trapped in the atmosphere 100 years from now.

HALOCARBONS

• Halocarbons are carbon based molecules that have chlorine, fluorine, or bromine in them.

• They contribute global warming as well as they have ability to destroy ozone.

• Some greenhouse gases, such as industrial halocarbons, are only made by humans, and thus their presence in the atmosphere can only be explained by human activity.

HALOCARBONS

• The most commonly occurring halocarbon is methyl chloride (CH3Cl), which is produced variously through fungal decaying, marine organism metabolism and burning of biomass (e.g. forest fires).

• Other sources of halocarbons are as follows: (a) Release of refrigerants into the atmosphere.

HALOCARBONS

(b) Accidental release of tetrachloroethylene, carbon tetrachloride and other industrial solvents into the environment.(c) Slash-and burn agriculture, whereby indigenous people burn forests for quick yields of charcoal and first year crops.

HALOCARBONS• Since most halocarbons absorb radiant reflected

sunlight, they contribute to the heating of the troposphere, and thus function as a greenhouse gas.

• Although there is a wide variation in the Global Warming Potential (GWP) among the halocarbons, these chemicals generally have a much greater GWP than either methane or carbon dioxide.

• Halocarbons which reach the stratosphere have significant effects of destroying the ozone layer.

OZONE GAS: (O3)

• The ozone layer is a belt of naturally occurring ozone gas that sits 9.3 to 18.6 miles (15 to 30 kilometers) above Earth and serves as a shield from the harmful ultraviolet B-radiation emitted by the sun.

OZONE GAS: (O3)

OZONE GAS: (O3)

• Ozone is a highly reactive molecule that contains three oxygen atoms. It is constantly being formed and broken down in the high atmosphere, 6.2 to 31 miles (10 to 50 kilometers) above Earth, in the region called the stratosphere.

OZONE GAS: (O3)

• Today, there is widespread concern that the ozone layer is deteriorating due to the release of pollution containing the chemicals chlorine and bromine. Such deterioration allows large amounts of ultraviolet B rays to reach Earth, which can cause skin cancer and cataracts in humans and harm animals as well.

OZONE GAS: (O3)

• Chlorofluorocarbons (CFCs), chemicals found mainly in spray aerosols heavily used by industrialized nations for much of the past 50 years, are the primary culprits in ozone layer breakdown. When CFCs reach the upper atmosphere, they are exposed to ultraviolet rays, which cause them to break down into substances that include chlorine. The chlorine reacts with the oxygen atoms in ozone and rips apart the ozone molecule.

OZONE GAS: (O3)

• According to the U.S. Environmental Protection Agency, one atom of chlorine can destroy more than a hundred thousand ozone molecules.

OZONE GAS: (O3)

OZONE GAS: (O3)

AEROSOLS

• Suspensions of particles having an effective diameter of less than 10µm are called aerosols.

• Some particles enter the atmosphere as solids (e.g. solid dust) and other are formed in the atmosphere when gases such as sulfur dioxide condense into liquid particles such as sulfates.

• Combustion of fossil fuels and biomass burning are the principal sources.

AEROSOLS• They affect the earth’s energy balance in

following three ways. (1) They can reflect incoming solar radiation back

into space, which increase the earth’s albedo.(2) They can provide cloud the condensation nuclei,

which increases the clouds reflectivity and cloud lifetime, and those also increases albedo.

(3) Carbonaceous particles, such as soot from fossil-fuel combustion, can increase the atmosphere absorption of incoming solar energy.

AEROSOLS• CO2, Nitrous oxide (N2O), Methane (CH4), and

halocarbons are well mixed, long-lived greenhouse gases. Lifetime of these gases is measured in decades. Lifetime of Aerosols is measured in days.

• When you look up at the sky, you are looking at more than just air. There are also billions of tiny bits of solid and liquid floating in the atmosphere. Those tiny floating particles are called aerosols or particulates.

AEROSOLS• Some aerosols are so small that they are made

only of a few molecules – so small that they are invisible because they are smaller than the wavelength of light. Larger aerosols are still very small, but they are visible.

• There are hundreds or thousands of little aerosols in each cubic centimeter of air. Some of them are natural and others are released into the air by humans.

AEROSOLS• Natural sources of aerosols include dust from dry

regions that is blown by the wind, particles released by erupting volcanoes or forest fires, and salt from the ocean.

• We, humans, add aerosols to the atmosphere too. Aerosols are a part of air pollution from cars, power plants, and factories that burn fossil fuels.

AEROSOLS• Some aerosols are released into the atmosphere,

others are made in the atmosphere. For example, sulfate aerosols are made in the atmosphere from sulfur dioxide released from power plants.

AEROSOLS

AEROSOLS• In general, the smaller and lighter a particle is,

the longer it will stay in the air. Larger particles tend to settle to the ground by gravity in a matter of hours whereas the smallest particles (less than 1 micrometer) can stay in the atmosphere for weeks and are mostly removed by precipitation.

AEROSOLS• For several reasons, aerosols affect climate. • Aerosols help clouds to form in the sky and the

number and types of clouds affects climate. • Certain types are able to scatter or absorb

sunlight, which affects climate. • Aerosols that scatter light can make interesting

distortions in the sky, called atmospheric optics.

AEROSOLS• The aerosols that are from air pollution are

hazardous to human health. • When the little particles get deep into a person’s

lungs it can make him or her very ill.• Aerosols can also limit visibility, causing haze in

many parts of the world.

GLOBAL WARMING POTENTIAL

• CH4 (Methane) has a global warming potential of 21 because it is 21 times as powerful as a greenhouse gas as CO2 (CO2 has a GWP of 1).

• Global-warming potential (GWP) is a relative measure of how much heat a greenhouse gas traps in the atmosphere.

• It compares the amount of heat trapped by a certain mass of a gas to the amount of heat trapped by a similar mass of CO2.

GLOBAL WARMING POTENTIAL

THE CARBON CYCLE

• Carbon is an element. It is part of oceans, air, rocks, soil and all things. Carbon doesn’t stay in one place. It is always on the move.

• Carbon moves from the atmosphere to plants: In the atmosphere, carbon is attached to oxygen in a gas called (CO2). With the help of the Sun, through the process of photosynthesis, carbon dioxide is pulled from the air to make plant food from carbon.

THE CARBON CYCLE

• Carbon moves from plants to animals.Through food chains, the carbon that is in plants moves to the animals which eat them. Animals that eat other animals get the carbon from their food too.

THE CARBON CYCLE

• Carbon moves from plants and animals to the ground.When plants and animals die, their bodies, wood and leaves decay bringing the carbon into the ground. Some becomes buried miles underground and will become fossil fuels in millions and millions of years.

THE CARBON CYCLE

• Carbon moves from living things to the atmosphere.Each time you exhale, you are releasing carbon dioxide gas (CO2) into the atmosphere. Animals and plants get rid of carbon dioxide gas through a process called respiration.

THE CARBON CYCLE• Carbon moves from fossil fuels to the atmosphere

when fuels are burned.When humans burn fossil fuels to power factories, power plants, cars and trucks, most of the carbon quickly enters the atmosphere as carbon dioxide gas. Each year, five and a half billion tons of carbon is released by burning fossil fuels. That’s the weight of 100 million adult African elephants! Of the huge amount of carbon that is released from fuels, 3.3 billion tons enters the atmosphere and most of the rest becomes dissolved in seawater.

THE CARBON CYCLE• Carbon moves from the atmosphere to the

oceans. The oceans, and other bodies of water, soak up some carbon from the atmosphere.

THE CARBON CYCLE• Carbon dioxide is a greenhouse gas and traps

heat in the atmosphere. Without it and other greenhouse gases, Earth would be a frozen world. But humans have burned so much fuel that there is about 30% more carbon dioxide in the air today than there was about 150 years ago.

• Most of the carbon in the atmosphere exists as carbon dioxide (CO2) and to a lesser extent, methane (CH4).

THE CARBON CYCLE• Although CO2 and CH4 are trace gases, which

occur in very small concentrations, they are both important greenhouse gases.

• The concentration of CO2 and CH4 in the atmosphere strongly affects the strength of the greenhouse effect and consequently the Earth's mean temperature.

THE CARBON CYCLE

CARBON EMISSIONS FROM FOSSIL FUELS

• Fossil fuel usage is expected to increase as the world's population continues to increase.

• Scientists have determined that approximately 40% of the carbon dioxide produced by burning fossil fuels is being absorbed by the terrestrial and ocean biosphere.

• The other 60% is staying in the atmosphere, and as a consequence, carbon dioxide is at its highest level in millions of years.


• So, what can individuals, organizations or governments do to reduce the amount of CO2 in the atmosphere?

• The burning of fossil fuels pollutes the atmosphere, degrades local environments, causes health and smog problems.


THE OCEANS AND CLIMATE CHANGE

• The ocean has been called the "global heat engine." Energy escapes the ocean in the forms of heat and water vapor.

• As the atmosphere warms, temperature gradients are created, resulting in surface winds that, in turn, drive ocean currents.

• These winds and water vapor also dramatically affect meteorological conditions, resulting in the formation of clouds or even rainstorms that are vital for life on land.



• Sea spray and water vapor form low clouds that ultimately cool temperatures at the surface.

• Meanwhile, desert dust and carbon dioxide settle into the ocean and act as "fertilizer" to stimulate the growth of phytoplankton (plankton consisting of microscopic plants), thereby enhancing the ocean's ability to absorb carbon dioxide from the atmosphere -- a process known as the "biological pump."


THE OCEANS AND CLIMATE CHANGE (Marine Phytoplankton)


• Phytoplankton forms the basis of the marine food chain.

• “Phytoplankton is the fuel on which marine ecosystems run. A decline of phytoplankton affects everything up the food chain, including humans.”


CHANGES IN STRATOSPHERIC OZONE

• By the time chlorine-containing compounds reach the stratosphere, they have been distributed globally. However, ozone depletion is most significant at the poles and in particular over the Antarctic continent at the South Pole.

• Figure indicates the large difference between ozone concentrations at the South and North Poles.

• Change in stratospheric ozone concentrations in the stratosphere is shown in the figure below.

CHANGES IN STRATOSPHERIC OZONE

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Chapter 4; global atmosphere change

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