8/14/2019 Air Resources and State of the Atmospheric Environment
1/64
Air Resources and State of the
Atmospheric Environment
8/14/2019 Air Resources and State of the Atmospheric Environment
2/64
The Earths Atmosphere
Blanket of air surrounding the earth that protects
us by blocking the dangerous radiation from the
sun and reducing temperature extremes betweenday and night.
Composed of mixture of gases that gradually thins
out as it reaches space
composed of Nitrogen (78%), Oxygen (21%), and
other gases (1%).
8/14/2019 Air Resources and State of the Atmospheric Environment
3/64
Composition of the Atmosphere
Percent Composition ofDry Atmosphere,by volume - ppmv: partsper million by volume
Gasper NASA
Nitrogen (N2)
78.084%
Oxygen (O2)
20.946%
Argon (Ar)
0.9340%
http://en.wikipedia.org/wiki/Parts_per_millionhttp://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.htmlhttp://en.wikipedia.org/wiki/Nitrogenhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Argonhttp://en.wikipedia.org/wiki/Image:Atmosphere_gas_proportions.gifhttp://en.wikipedia.org/wiki/Argonhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Nitrogenhttp://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.htmlhttp://en.wikipedia.org/wiki/Parts_per_million8/14/2019 Air Resources and State of the Atmospheric Environment
4/64
Carbon dioxide (CO2)
365 ppmv
Neon (Ne) 18.18 ppmv Helium (He) 5.24 ppmv
Methane (CH4)1.745 ppmv
Krypton (Kr) 1.14 ppmv
Hydrogen (H2) 0.55 ppmv
Not included in above
composition
of dry atmosphere:
Water vaporHighly variable;
typically makes up about 1%
Minor components of airnot listed above include:
nitrous oxide (0.5 ppmv
xenon (0.09 ppmv) ozone (0.0 to 0.07 ppmv,
0.0 to 0.02 ppmv inwinter)
nitrogen dioxide (0.02
ppmv), iodine (0.01 ppmv),
carbon monoxide (0.0 totrace)
ammonia (0.0 to trace).
http://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Neonhttp://en.wikipedia.org/wiki/Heliumhttp://en.wikipedia.org/wiki/Methanehttp://en.wikipedia.org/wiki/Kryptonhttp://en.wikipedia.org/wiki/Hydrogenhttp://en.wikipedia.org/wiki/Water_vaporhttp://en.wikipedia.org/wiki/Nitrous_oxidehttp://en.wikipedia.org/wiki/Xenonhttp://en.wikipedia.org/wiki/Ozonehttp://en.wikipedia.org/wiki/Winterhttp://en.wikipedia.org/wiki/Nitrogen_dioxidehttp://en.wikipedia.org/wiki/Iodinehttp://en.wikipedia.org/wiki/Carbon_monoxidehttp://en.wikipedia.org/wiki/Ammoniahttp://en.wikipedia.org/wiki/Ammoniahttp://en.wikipedia.org/wiki/Carbon_monoxidehttp://en.wikipedia.org/wiki/Iodinehttp://en.wikipedia.org/wiki/Nitrogen_dioxidehttp://en.wikipedia.org/wiki/Winterhttp://en.wikipedia.org/wiki/Ozonehttp://en.wikipedia.org/wiki/Xenonhttp://en.wikipedia.org/wiki/Nitrous_oxidehttp://en.wikipedia.org/wiki/Water_vaporhttp://en.wikipedia.org/wiki/Hydrogenhttp://en.wikipedia.org/wiki/Kryptonhttp://en.wikipedia.org/wiki/Methanehttp://en.wikipedia.org/wiki/Heliumhttp://en.wikipedia.org/wiki/Neonhttp://en.wikipedia.org/wiki/Carbon_dioxide8/14/2019 Air Resources and State of the Atmospheric Environment
5/64
The evolution of the Earth's
atmosphere The modern atmosphere is sometimes
referred to as Earth's "third atmosphere", in
order to distinguish the current chemicalcomposition from two notably differentprevious compositions.
The original atmosphere was primarilyhelium and hydrogen; heat (from the stillmolten crust, and the sun) dissipated thisatmosphere.
8/14/2019 Air Resources and State of the Atmospheric Environment
6/64
About 3.5 billion years ago, the surface had cooled
enough to form a crust, still heavily populated
with volcanoes which released steam,carbon dioxide, and ammonia.
This led to the "second atmosphere"; which was,
primarily, carbon dioxide and water vapor, with
some nitrogen but virtually no oxygen
This second atmosphere had ~100 times as much
gas as the current atmosphere. It is generally
believed that the greenhouse effect, caused byhigh levels of carbon dioxide, kept the Earth from
freezing.
http://en.wikipedia.org/wiki/Crusthttp://en.wikipedia.org/wiki/Volcanohttp://en.wikipedia.org/wiki/Steamhttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Ammoniahttp://en.wikipedia.org/wiki/Water_vaporhttp://en.wikipedia.org/wiki/Nitrogenhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Multiplicationhttp://en.wikipedia.org/wiki/Gashttp://en.wikipedia.org/wiki/Greenhouse_effecthttp://en.wikipedia.org/wiki/Freezinghttp://en.wikipedia.org/wiki/Freezinghttp://en.wikipedia.org/wiki/Greenhouse_effecthttp://en.wikipedia.org/wiki/Gashttp://en.wikipedia.org/wiki/Multiplicationhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Nitrogenhttp://en.wikipedia.org/wiki/Water_vaporhttp://en.wikipedia.org/wiki/Ammoniahttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Steamhttp://en.wikipedia.org/wiki/Volcanohttp://en.wikipedia.org/wiki/Crust8/14/2019 Air Resources and State of the Atmospheric Environment
7/64
In the next few billion years, water vapor condensed to
form rain and oceans, which then dissolved the carbon
dioxide
About 50 % of CO2 were absorbed into the ocean
The first life forms were the cyanobacteria and were the
first oxygen producing evolving phototropic organisms.
Cyanobacteria converted the earths atmosphere froman anoxic (state without oxygen) to an oxic (with
oxygen) state. Being the first to carry out oxygenic
photosynthesis, they were able to convert carbon
dioxide into oxygen playing a major role inoxygenating the atmosphere.
8/14/2019 Air Resources and State of the Atmospheric Environment
8/64
Eventually, photosynthesizing plants evolved andconverted more carbon dioxide to oxygen
Excess carbon were locked in fossil fuels,sedimentary rocks (limestone), and animal shells.
The oxygen released reacted with ammonia to formnitrogen, aside from bacteria converting ammonia to
nitrogen The appearance of more plants increased the levels
of oxygen significantly but the concentration of CO2dropped.
The oxygen produced first reacted with variouselements like iron but eventually accumulated in theatmosphere resulting to mass extinction and furtherevolution
8/14/2019 Air Resources and State of the Atmospheric Environment
9/64
Ozone layer started
to appear and lifeforms were better
protected from the
UV
The oxygen-nitrogenatmosphere is the
"third atmosphere".
http://www.windows.ucar.edu/tour/link=/earth/images/atmosphere_image.html8/14/2019 Air Resources and State of the Atmospheric Environment
10/64
Air Resources
Nitrogen being the mostabundant gas in theatmosphere is formed from
reaction of ammonia withoxygen
Dilutes oxygen and carbondioxide
Helps slow down decay,
rusting, and burning Liquefaction and fractional
distillation of N2 from the
atmosphere
Uses of nitrogen
Cryogenics and refrigerant
responsible for the orange-red, blue-green, blue-violet,
and deep violet colors of theaurora.
Component of proteins,foods, fertilizers, poison, andexplosives
Annealing steel andblanketing medium duringproduction of electroniccomponents
8/14/2019 Air Resources and State of the Atmospheric Environment
11/64
Oxygen is a by-
product of
photosynthesis
It combines easily
with many substances Supports life
Supports burning
process
Uses:
oxy-acetylene welding
frequently used to aidrespiration of patientsin hospitals
used in makingmethanol and ethene
oxide rocket fuel oxidant
steel manufacture
ozone (O3) in theatmosphere isprotection against thesun's ultraviolet rays
8/14/2019 Air Resources and State of the Atmospheric Environment
12/64
Carbon dioxide although small in
concentration plays a role in warming theatmosphere
Produced by animal respiration, burning of
fuels, , and by volcanic eruption Important to life of plant
Not poisonous, but too much of it in the air
lessens the amount of oxygen breathed in byhumans and animals
8/14/2019 Air Resources and State of the Atmospheric Environment
13/64
Carbon is one of the most common element that
has unique properties (can form bond with itself or
with other elements Found in all living organisms
Can be found in compounds that can exist as gas,
liquid, or solid on the earths surface Thus carbon can help form solid minerals such as
limestone, plants and animals, and carbon dioxide
that can be carried around the world through the
atmosphere and be dissolved in water This makes possible the existence of carbon in
compounds which are essential to life on earth
8/14/2019 Air Resources and State of the Atmospheric Environment
14/64
Carbon atoms continually move through livingorganisms, the oceans, the atmosphere, and in thecrust of the planet (carbon cycle)
The paths taken by carbon through this cycle arecomplex and take millions of years to complete thecycle (coal and crude oil).
Others may take days or simply hours to pass the
cycle (Burning) The aggregation of the possible paths of carbon,
where it may be stored for extended periods (the"sinks"), where it is likely to be released to the
atmosphere (the "source"), and what triggers thosesources (the "release agents"), together defines thecarbon cycle.(Global Climates - Past, Present, and Future, S. Henderson, S. Holman, and L.Mortensen (Eds.). EPA Report No. EPA/600/R-93/126, U.S. Environmental Protection Agency, Office ofResearch and Development, Washington, DC. pp. 59 - 64.)
8/14/2019 Air Resources and State of the Atmospheric Environment
15/64
The Carbon Cycle
8/14/2019 Air Resources and State of the Atmospheric Environment
16/64
Carbon sinks includelong-lived trees,
limestone (formed fromthe carbon-containingshells of small seacreatures that settle tothe ocean bottoms and
build up into thickdeposits), plastic (amodern invention, butvery long-lived), and theburial of organic matter
(such as those thatformed the fossil fuelswe use today).
8/14/2019 Air Resources and State of the Atmospheric Environment
17/64
Carbon sources
include the burning
of fossil fuels and
other organic matter,
the weathering of
limestone rocks(which releases ),
and the respiration
of living organisms.
8/14/2019 Air Resources and State of the Atmospheric Environment
18/64
Release agents
include volcanic
activity, forest fires,and many human
activities.
8/14/2019 Air Resources and State of the Atmospheric Environment
19/64
The other 1% is composed of "trace" gases, themost prevalent of which is the inert gaseouselement argon. The rest of the trace gases,although present in only minute amounts, arevery important to life on earth.
Two in particular, carbon dioxide and ozone, canhave a large impact on atmospheric processes.
Another gas, water vapor, also exists in smallamounts. It varies in concentration from beingalmost non-existent over desert regions to about4% over the oceans. Water vapor is important to
weather production since it exists in gaseous,liquid, and solid phases and absorbs radiantenergy from the earth.
8/14/2019 Air Resources and State of the Atmospheric Environment
20/64
Other trace gases suchas methane, oxides of
nitrogen are transparentto UC radiation but canabsorb outgoinginfrared radiation, in
effect trapping the heatenergy. This trappedheat energy makes theearth warmer than itwould be without thesetrace gases. (GHG)
8/14/2019 Air Resources and State of the Atmospheric Environment
21/64
This phenomenon has been called the"greenhouse effect" because the trace
gases trap heat similar to the way that agreenhouse's transparent coveringtraps heat.
Without our atmospheric greenhouseeffect, earth's surface temperaturewould be far below freezing.
On the other hand, an increase in
atmospheric trace gases could result inincreased trapped heat and risingglobal temperatures.
8/14/2019 Air Resources and State of the Atmospheric Environment
22/64
8/14/2019 Air Resources and State of the Atmospheric Environment
23/64
It extends from the earth's
surface to an average of 12
km (7 miles).
The pressure ranges from
1000 to 200 millibars (29.92
in. to 5.92 in.).
The temperature generallydecreases with increasing
height up to the tropopause
(top of the troposphere);
this is near 200 millibars or36,000 ft.
8/14/2019 Air Resources and State of the Atmospheric Environment
24/64
The temperature averages 15C (59F) near the
surface and -57C (-71F) at the tropopause.
The layer ends at the point where temperature no
longer varies with height. This area, known as the
tropopause, marks the transition to the
stratosphere.
Winds increase with height up to the jet stream. The moisture concentration decreases with height
up to the tropopause.
The air is much drier above the tropopause, in the
stratosphere.
8/14/2019 Air Resources and State of the Atmospheric Environment
25/64
The sun's heat that warms the earth'ssurface is transported upwards largely by
convection and is mixed by updrafts and
downdrafts.
The troposphere is 70% and 21% . The
lower density of molecules higher up would
not give us enough to survive.
8/14/2019 Air Resources and State of the Atmospheric Environment
26/64
Troposphere-air flow is
usually horizontal
Ozone layer responsiblefor absorbing the ultraviolet
radiation from the suin
Above the stratosphere is
the mesosphere and abovethat is the ionosphere (or
thermosphere), where
many atoms are ionized
(have gained or lost
electrons so they have a
net electrical charge).
8/14/2019 Air Resources and State of the Atmospheric Environment
27/64
The ionosphere is very thin, but it is whereaurora take place, and is also responsible for
absorbing the most energetic photons fromthe Sun, and for reflecting radio waves,thereby making long-distance radiocommunication possible.
The structure of the ionosphere is stronglyinfluenced by the charged particle wind fromthe Sun (solar wind), which is in turngoverned by the level of Solar activity.
8/14/2019 Air Resources and State of the Atmospheric Environment
28/64
State of the Atmospheric
Environment Most scientists believe that human
activity is altering the composition of the
atmosphere by increasing theconcentration of greenhouse gases
(GHGs). Greenhouse gases occur
naturally in the atmosphere and theirpresence results in what atmospheric
scientists call the greenhouse effect.
8/14/2019 Air Resources and State of the Atmospheric Environment
29/64
It is important to remember that the
greenhouse effect is what keeps the earth
warm enough to be habitable.
The current concern is directed at an
enhanced greenhouse effect, one that
would put more heat-absorbing gases into
the atmosphere, thereby increasing globaltemperatures.
The enhanced greenhouse effect has
been linked to increased GHG emissionsfrom human activities.
8/14/2019 Air Resources and State of the Atmospheric Environment
30/64
The recent attention given to the
greenhouse effect and global warming
is based on the recorded increases inconcentrations of some of the
greenhouse gases due to human
activity. Of particular interest are watervapor, carbon dioxide, methane, nitrous
oxide, chlorofluorocarbons, and ozone.
With the exception of
chlorofluorocarbons, all of these gases
occur naturally and are also produced
by human activity.
8/14/2019 Air Resources and State of the Atmospheric Environment
31/64
Water vaporis the most important GHG on theplanet.
Unlike most of the other atmospheric gases, water
vapor is considered to be a 'variable' gas; that is,the percentage of water vapor in the atmospherecan vary greatly depending on the location andsource of the air.
Water vapor absorbs heat readily. human activity is not directly changing water vapor
content.
But man, directly influence other GHGs. Although
other GHGs are individually less important thanwater vapor, increasing their concentrations mayaffect global climate in significant and measurableways.
8/14/2019 Air Resources and State of the Atmospheric Environment
32/64
Carbon dioxide (CO2) is considered the
most important human-influenced GHG.
Over geologic time, sources and sinks
generally balance. In today's
atmosphere, however, levels areclimbing in a dramatic and easily
measurable fashion, providing evidence
that there are now more sources thansinks.
8/14/2019 Air Resources and State of the Atmospheric Environment
33/64
What are the sources for this
'extra' CO2? Human activities primarily responsible for the
increases Fossil fuel combustion accounts for 65%
Deforestation ( released from trees that are cutand burned or left to decay) accounts for 33%
The by-products of cement production account forthe remaining 2%
8/14/2019 Air Resources and State of the Atmospheric Environment
34/64
natural sources of CO2 Plants and animals give off CO2 while alive
and respiring and when dead and decaying(bacteria that consume the dead bodiesrespire too, after all).
Carbonate rocks contain CO2 that can be
released by exposure to acid and/orweathering. Certain naturally carbonatedspring waters contain CO2 because the water
has passed though carbonate rocks on its wayto the surface.
Volcanoes geological sources are insignificant when
compared to the human sources.
8/14/2019 Air Resources and State of the Atmospheric Environment
35/64
Methane (CH4 ) largely a product of natural biologic processes, but
its output can be accelerated by human activities.
emitted from the decay of organic matter inwaterlogged soils (for example, wetlands and rice
paddies) and from the digestive tracts of grazinganimals (for example, ruminants).
increased concn. from human activities include theexpansion of rice agriculture, the increased number
of livestock, the increased number of landfills, andleakage from natural gas pipelines.
8/14/2019 Air Resources and State of the Atmospheric Environment
36/64
Nitrous oxide (N2O )
naturally occurring GHG but the concn.
increased significantly because of human
activities
is emitted from coal-burning power plants
and can be released from the breakdown
of chemical fertilizers in the soil.
From automobiles
8/14/2019 Air Resources and State of the Atmospheric Environment
37/64
Ozone (O3 )
also a greenhouse gas.
It is important not to confuse the presence of the
ozone in the stratosphere (a good thing) with the
presence of ozone in the troposphere (a bad thing).
In the troposphere, ozone can be a major
component of urban smog damaging crops and
aggravating respiratory problems as well as
enhancing the greenhouse effect.
8/14/2019 Air Resources and State of the Atmospheric Environment
38/64
Chlorofluorocarbons (CFCs)
have no natural source;
produced entirely by human activity.
been used widely as refrigerants in air conditioners,refrigerators, freezers, and heat pumps.
found in some foam plastics and used in someelectronics manufacturing.
Even though CFC production has been vastlyreduced, these compounds remain in the atmosphere
for a long time; we shall see their effects as GHGs formany years.
8/14/2019 Air Resources and State of the Atmospheric Environment
39/64
Other substances emitted to the atmosphere
HydrocarbonsOther organic substances
Heavy metals such as lead
Particulate matter
8/14/2019 Air Resources and State of the Atmospheric Environment
40/64
While the earth's temperature is dependentupon the greenhouse-like action of theatmosphere, the amount of heating and
cooling are strongly influenced by severalfactors just as greenhouses are affected byvarious factors.
In the atmospheric greenhouse effect, the type
of surface that sunlight first encounters is themost important factor.
Forests, grasslands, ocean surfaces, ice caps,deserts, and cities all absorb, reflect, and
radiate radiation differently. Sunlight falling ona white glacier surface strongly reflects backinto space, resulting in minimal heating of thesurface and lower atmosphere.
8/14/2019 Air Resources and State of the Atmospheric Environment
41/64
Sunlight falling on a dark desert soil is stronglyabsorbed, on the other hand, and contributes to
significant heating of the surface and loweratmosphere. Cloud cover also affectsgreenhouse warming by both reducing theamount of solar radiation reaching the earth'ssurface and by reducing the amount of radiation
energy emitted into space. Scientists use the term albedo to define the
percentage of solar energy reflected back by asurface. Understanding local, regional, and
global albedo effects is critical to predictingglobal climate change.
8/14/2019 Air Resources and State of the Atmospheric Environment
42/64
Atmospheric Processes
From the cycle, water is an essential
part of the earth's system.
The oceans cover nearly three-quartersof the earth's surface and play an
important role in exchanging and
transporting heat and moisture in theatmosphere.
8/14/2019 Air Resources and State of the Atmospheric Environment
43/64
Most of the water
vapor in the
atmospherecomes from the
oceans.
Most of the
precipitation
falling over land
finds its wayback to oceans
8/14/2019 Air Resources and State of the Atmospheric Environment
44/64
About two-thirds returns to the
atmosphere via the water cycle
the oceans and atmosphere interactextensively.
Oceans not only act as an abundant
moisture source for the atmosphere butalso as a heat source and sink
(storage).
The exchange of heat and moisture hasprofound effects on atmospheric
processes near and over the oceans.
8/14/2019 Air Resources and State of the Atmospheric Environment
45/64
Ocean currents play a significant role in
transferring this heat poleward. Majorcurrents, such as the northward flowing GulfStream, transport tremendous amounts ofheat poleward and contribute to thedevelopment of many types of weatherphenomena. They also warm the climate ofnearby locations. Conversely, cold southwardflowing currents, such as the Californiacurrent, cool the climate of nearby locations.
8/14/2019 Air Resources and State of the Atmospheric Environment
46/64
Energy Heat Transfer
Practically all of theenergy that reaches theearth comes from thesun. Intercepted first bythe atmosphere, a smallpart is directlyabsorbed, particularlyby certain gases suchas ozone and water
vapor. Some energy isalso reflected back tospace by clouds and theearth's surface.
8/14/2019 Air Resources and State of the Atmospheric Environment
47/64
8/14/2019 Air Resources and State of the Atmospheric Environment
48/64
Conduction is theprocess by which heatenergy is transmittedthrough contact withneighboringmolecules.
Some solids, such as
metals, are goodconductors of heatwhile others, such aswood, are poor
conductors. Air andwater are relativelypoor conductors.
Since air is a poorconductor, most energytransfer by conduction
occurs right at theearth's surface. At night,the ground cools andthe cold ground
conducts heat awayfrom the adjacent air.During the day, solarradiation heats theground, which heats the
air next to it byconduction.
8/14/2019 Air Resources and State of the Atmospheric Environment
49/64
Convection transmits
heat by transporting
groups of molecules
from place to placewithin a substance.
Convection occurs in
fluids such as water and
air, which move freely. In the atmosphere,
convection includes
large- and small-scale
rising and sinking of airmasses and smaller air
parcels.
These verticalmotions effectively
distribute heat andmoisture throughoutthe atmosphericcolumn andcontribute to cloudand stormdevelopment (whererising motion occurs)and dissipation
(where sinkingmotion occurs).
To understand the
8/14/2019 Air Resources and State of the Atmospheric Environment
50/64
To understand theconvection cells thatdistribute heat over thewhole earth, let's consider a
simplified, smooth earth withno land/sea interactions anda slow rotation. Under theseconditions, the equator iswarmed by the sun more
than the poles. The warm,light air at the equator risesand spreads northward andsouthward, and the cooldense air at the poles sinks
and spreads toward theequator. As a result, twoconvection cells are formed.
8/14/2019 Air Resources and State of the Atmospheric Environment
51/64
the slow rotation ofthe earth toward the
east causes the airto be deflectedtoward the right inthe northernhemisphere andtoward the left in thesouthernhemisphere. Thisdeflection of the
wind by the earth'srotation is known asthe Coriolis effect.
Radiation is thetransfer of heat energy
without the
involvement of a
physical substance in
the transmission.
Radiation can transmit
heat through a
vacuum.
E t l f th t
8/14/2019 Air Resources and State of the Atmospheric Environment
52/64
Energy travels from the sun tothe earth by means ofelectromagnetic waves. Theshorter the wavelength, the
higher the energy associatedwith it. This is demonstrated inthe animation below. As thedrill's revolutions per minute(RPMs) increase, the number
of waves generated on thestring increases, as does theoscillation rate. The sameprinciple applies toelectromagnetic waves from
the sun, where shorterwavelength radiation hashigher energy than longerwavelength radiation.
8/14/2019 Air Resources and State of the Atmospheric Environment
53/64
Most of the sun's radiant energy is concentrated inthe visible and near-visible portions of thespectrum. Shorter-than-visible wavelengths
account for a small percentage of the total but areextremely important because they have muchhigher energy. These are known as ultravioletwavelengths
The physical and chemical structure of theatmosphere, the way that the gases interact withsolar energy, and the physical and chemicalinteractions between the atmosphere, land, andoceans all combine to make the atmosphere an
integral part of the global biosphere.
8/14/2019 Air Resources and State of the Atmospheric Environment
54/64
Overview of processes and properties
associated with global climate change
Earth's climate has always changed; it is the rateof change that is of current concern to scientists.
Carbon is critical to the biosphere and mustcontinue cycling to support life on Earth.
The carbon cycle includes sources, sinks, andrelease agents.
Carbon dioxide is an important greenhouse gas.
Living organisms in an ecosystem can haveprofound effects upon the local atmosphere.
8/14/2019 Air Resources and State of the Atmospheric Environment
55/64
Understanding the major greenhouse
gases is necessary to identify the
current trends in atmosphericconcentrations and climate change.
Changes in vegetation can have
profound effects upon wind speed. Human activity has been linked with
increased greenhouse gases in the
atmosphere.
8/14/2019 Air Resources and State of the Atmospheric Environment
56/64
Present Climates and Human
Activity The discovery of fossil fuels and the means of
turning the energy trapped within them into heat,
transportation, and the basis for manufacturingand construction and the global industrial
revolution that followed changed the world
forever for our species
8/14/2019 Air Resources and State of the Atmospheric Environment
57/64
Since the 1800s, CO2
concentrations worldwide
have increased fromapproximately 280 ppm
(or 0.028%) to around 365
ppm (0.0365%). The
increase seems trivial, butit also means that some 3
gigatons (3 billion metric
tons) of CO2are being
added to the atmosphere
every year.
8/14/2019 Air Resources and State of the Atmospheric Environment
58/64
Because CO2 is a powerful
greenhouse gas, it can beconcluded that the earth'stemperature should go upas CO2 concentrations
increase.
climatologists havedetected a steady but smallincrease in global average
temperatures over the lastfew decades, based onweather data collected allaround the world. Six of thelast ten were the hottest
years on record.
8/14/2019 Air Resources and State of the Atmospheric Environment
59/64
Regardless of the cause of thewarming, we understand enough about
global climate to predict that as the
temperature goes up, the entire globalclimate system powered by heat energy
should also change, although the
magnitude and direction of the changes
are uncertain
8/14/2019 Air Resources and State of the Atmospheric Environment
60/64
Future climates- The Great
Uncertainty Will the climate change for the worse because of our
actions?
In fact, no one knows for sure. Most atmospheric
scientists believe that the global climate is warmingat least partially because of a build-up of CO2 from
fossil fuel use, but what that means to humans andnatural ecosystems is largely unknown.
The climate is vastly complex and strongly influencedby many factors other than greenhouse gasconcentrations
8/14/2019 Air Resources and State of the Atmospheric Environment
61/64
it extremely difficult to link any climatic events or
characteristics to a single cause.
As a result, controversy exists as to themagnitude and danger of global warming
induced by greenhouse gases.
Many scientists take the issue very seriously
and support efforts to slow or reverse the build-up of atmospheric CO2 with the expectation that
global warming will slow as a result. Others,
however, contend that CO2
may not be affecting
the climate and that the changes are part of
natural, long-term climatic cycles.
8/14/2019 Air Resources and State of the Atmospheric Environment
62/64
They suggest that efforts to reduceemissions are unnecessary and dangerousto economic growth and development.
While the controversy rages, researchersaround the world continue to gather
atmospheric data, develop and refinepredictive computer models, and try toreduce the uncertainty in ourunderstanding of the earth's climate.
8/14/2019 Air Resources and State of the Atmospheric Environment
63/64
With this, let us try to ponder on the
critical issues about the state of our
atmospheric environment and itsrelation to climate change, explore the
possibility of balancing the sources and
sinks (or reservoirs) of GHGs , thenature of climate change and predictions
of future changes, and the elements of
the scientific and political debates that
will ultimately determine how we respondto climate change
8/14/2019 Air Resources and State of the Atmospheric Environment
64/64
Top Related