Transcript Understanding Our Environment

Global Warming
Green House Gases
how global warming works
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Green house gases
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Many greenhouse gases occur naturally in
the atmosphere, such as water vapor (3670%), Carbon dioxide (9-26%), Methane ( 49%) and nitrous oxide, while others are
synthetic.
Those that are man-made (lower end)
include the Chlorofluorocarbons (CFCs),
Hydrofluorocarbons (HFCs),
Perfluorocarbons (PFCs),
Sulfur hexafluoride (SF6).
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Water Vapour
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Water Vapor is the most abundant greenhouse
gas in the atmosphere.
Although the media gives impression that (CO2)
is "the big one". water vapor is actually the
dominant greenhouse gas in Earth's
atmosphere.
As the temperature of the atmosphere rises,
more water is evaporated from ground storage
(rivers, oceans, reservoirs, soil.
Water, in gaseous form (as water vapor) and in
liquid form (as tiny droplets in clouds),
generates somewhere between 66% and 85% of
the greenhouse effect
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…..Water Vapour
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Water vapor generates more greenhouse
effect on our planet than does any other
single gas.
As water vapor increases in the
atmosphere, it eventually also condense
into clouds, which are more able to reflect
incoming solar radiation (thus allowing
less energy to reach the Earth's surface
and heat it up) ( Refer Water cycle).
Water cycle
Carbon dioxide (CO2)
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CO2 is a green gas next to water vapour & it helps trap
heat coming from the Sun in our atmosphere through the
green house effect.
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Carbon dioxide occur naturally in the atmosphere,
through our interference with the carbon cycle (through
burning forest lands, or mining and burning coal).
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We artificially move carbon from solid storage to its
gaseous state, thereby increasing atmospheric
concentrations.
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….Carbon dioxide (CO2)
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Carbon dioxide traps heat in the
atmosphere.
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Without it and other greenhouse gases,
Earth would be a frozen world.
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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.
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…Carbon Dioxide ( CO2)
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Concentrations of carbon dioxide in the
atmosphere are naturally regulated by
numerous processes collectively known
as the “carbon cycle” ( Ref Carbon cycle):
We breath in O2 and give out CO2
When humans burn fossil fuels to power
factories, power plants, cars and trucks,
most of the carbon quickly enters the
atmosphere as carbon dioxide ( five and a
half billion tons of carbon each year).
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….CO2
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Natural fires like forest fires make carbon
dioxide.
Things that humans burn make CO2.
The smoke stacks of factories that burn
coal give off carbon dioxide.
The engines of cars, trucks, and buses
also pump carbon dioxide into the air.
Vehicles give off another gas, carbon
monoxide, which combines with O2 and
form CO2
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…Carbon cycle
Nitrous oxide
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Nitrous oxide (N2O) is produced by both natural
and human-related sources.
Primary human-related sources of N2O are
agricultural soil management, animal manure
management, sewage treatment, mobile and
stationary combustion of fossil fuel,, and nitric
acid production.
Nitrous oxide is also produced naturally from a
wide variety of biological sources in soil and
water, particularly microbial action in wet
tropical forests ( Ref. nitrogen cycle).
…Nitrogen Cycle
Other Green Gas- Methane
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When most people think of climate change
they envision billowing smokestacks, and
diesel engines responsible for releasing
carbon dioxide into the atmosphere.
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We over looking a far more inconspicuous
culprit – methane– emissions of which may
be slowing down.
Methane manufacturers. [CREDIT: USDA ARIS
INFORMATION STAFF
….Other Green Gas- Methane
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The Earth's crust contains huge amounts of
methane.
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It is a chemical compound with the molecular
formula CH4.
It is a relatively potent greenhouse gas with a
high global warming potential.
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Burning methane in the presence of oxygen
produces carbon dioxide and water.
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….Other Green Gas -Methane
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Methane is the second most abundant
greenhouse gas, behind only carbon
dioxide, according to the new report from
the United Nations’ Intergovernmental
Panel on Climate Change.
Most natural methane comes from
bacteria that live in wetlands and
marshes, which multiply quickly in wet or
warm seasons.
Large amounts of methane are produced
anaerobically
….Other green House gases
Haloalkanes:
Consisting of alkanes, such as methane or ethane,
with one or more halogens linked, such as chlorine or
fluorine
• Used as flame retardants, fire extinguishants,
refrigerants, propellants and solvents they have or
had wide use
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Chlorofluorocarbons (CFC):
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Contains Chlorine
Gases such as CFC’s had damaged the ozone layer,
creating a huge hole through which dangerous
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Hence, it is forbidden to release CFC gasses into the
atmosphere, so all redundant refrigeration plant,
including air-conditioning and domestice fridges and
freezers must be properly decommissioned and drained
of their CFC gasses by a trained and certified
technician.
Hydrofluorocarbons (HFCs):
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contain no chlorine. They are composed entirely of carbon,
hydrogen, and fluorine.
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They have no known effects at all on the ozone layer.
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Only compounds containing chlorine and bromine are
thought to harm the ozone layer.
Green House Gas in the atmosphere
References
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http://lwf.ncdc.noaa.gov/oa/climate/gases.html#INT
RO
http://www.eia.doe.gov/bookshelf/brochures/greenh
ouse/Chapter1.htm
http://www.solarnavigator.net/greenhouse_gases.ht
m
http://www.neuse.ncsu.edu/nitrogen/
http://www.epa.gov/nitrousoxide/sources.html
http://www.umich.edu/~gs265/society/greenhouse.
htm
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http://scienceline.org/2007/03/23/env_knight
_ipcccows/
http://da.wikipedia.org/wiki/CFC-gas