l2 global warming
DESCRIPTION
Global WarmingTRANSCRIPT
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Sustainability and
Engineering Profession
(CON4433)
Lecture 2 - Global Warming &
Greenhouse Effect
VTC 2013
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Aim:
Understanding the definition of
greenhouse effect (GF)
Understanding the problem of global
warming
Discuss the solutions to stop global
warming
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Weather & climate
Physical properties of the troposphere like Temp., pressure, humidity, precipitation, sunlight, cloud cover, wind direction & speed at a given place & time weather
Long-term average weather of an area climate
Climate is a regions general pattern of weather conditions, seasonal variations & weather extremes over a long period
Temp. & precipitation are 2 important factors of climate
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What is Greenhouse?
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Greenhouse Effect
CO2, water vapour, ozone, methane, nitrous oxide, CFCs in the troposphere greenhouse gases
They allow light, IR radiation & some UV radiation from the sun to pass through but prevent the escape of the IR radiation emitted by the Earth
The trapping of heat in the troposphere is known as Greenhouse effect
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Greenhouse Effect
Is greenhouse effect good or bad for living
organisms on Earth?
Without the greenhouse gases,
the earth would have an average
surface temp of -18C instead of its
current 15C
The earth would be cold and lifeless
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Carbon dioxide
Carbon dioxide is an important
Greenhouse gas.
It is a minor component of the atmosphere
(0.03%) but it plays a major part in the
carbon cycle
CO2 is produced in respiration,
fermentation and combustion. It is used by
plants in photosynthesis.
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Carbon dioxide
CO2 is unreactive and is not considered as
a pollutant
CO2 has a large share of the responsibility
for the greenhouse effect of the Earth
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Carbon dioxide
In the past century, human activity has added ~360 billion tons of CO2 to the atmosphere, its conc. in the atmosphere by 25% 0.6C rise in the earths temp.
Average CO2 content of the atmosphere by >9% since 1958. The current rate of is 1 ppm per year
There will be 660 ppm of CO2 by mid 21st Century (twice that in 1900)
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Global Warming
Global warming is the in the earths average temp & changes in the climate
Debate over whether human activities are intensifying the natural GH effect & cause global warming
Controversy over
How much the temp rise
How this temp rise affect the climate in different areas
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Global Warming Findings by
IPCC
Water vapour remained fairly constant in
the troposphere over the past 160,000
years.
CO2 have fluctuated.
Levels of CO2 correlate closely with mean
surface temp of the Earth.
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Global Warming Findings by
IPCC
Atmospheric levels of GH gases have
risen in recent decades
It include:
CO2,
methane,
nitrous oxide and
CFCs
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Global Warming Findings by
IPCC
Most of the in these GH gases have
been caused by human activities:
burning fossil fuels,
use of CFCs,
agriculture &
deforestation
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Global Warming Findings by
IPCC
So far, any temp changes is too small and
do not exceed normal short-term
variations in mean atmospheric temp
caused by volcanic eruptions, air pollution
& other climatic factors
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Global Warming Findings by
IPCC
Recent IPCC report mentioned that >90%
probable of fossil fuel burning explained
the warming
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Global Warming Findings by
IPCC Warming or cooling by >2C over a few decades
would be disastrous.
Such rapid climate change would alter
conditions faster than some species could adapt
or migrate.
Some areas might become uninhabitable.
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Global Warming Findings by
IPCC Accurate projections about the possible effects
of our inputs of GH gases on climates of
biosphere cannot be made
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Modelling Greenhouse Warming
Mathematical models have been
developed by scientist to simulate the
behaviour of climatic & other complex
systems. They are run on computers
The accuracy of the results depends on
the design of the model
accuracy of the input data & the assumptions
used
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Modelling Greenhouse Warming
main projections of climatic models
The Earths mean surface temp will 1.8-
4C in 21st Century. The Earth would be
warmer than it has been for 10,000 years
The Northern Hemisphere will warm more
& faster than the Southern Hemisphere
Temp at middle & high latitudes should
rise 2-3 times the global average
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Modelling Greenhouse Warming
main projections of climatic models
More areas will have extreme heat waves
& more forest fires
Average sea level will rise 2-4 cm per
decade
More droughts, heatwaves and sea level
could continue for >1000 years even
greenhouse gases emissions were
chopped
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Possible Effects of Global Warming
Whats the problem of a possible rise of
only a few degrees in the mean surface
temp of the Earth?
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Possible Effects of Global Warming
The rise in temp is NOT normal swings in
local weather, but a global change in
average climate
A warmer troposphere would have diff.
consequences for diff. people & species.
Some places would get drier, some wetter.
Some would be hotter, others cooler
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Possible Effects of Global Warming
Changes in food production. Projected
drops in yields of key food crops ~30%-
70%
Reduction in water supplies. Lakes,
streams & aquifers could shrink or dry up
Changes in forests. Forests in temperate
& subarctic regions would die out
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Possible Effects of Global Warming
Reduction in biodiversity. Large-scale
forest diebacks would cause mass
extinction of species. Shifts in regional
climate would result in huge loss of
biodiversity.
Rising sea level. It is caused by thermal
expansion of water & melting of glaciers at
the poles.
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Possible Effects of Global Warming
~ 1/3 of worlds population & >1/3 of the
worlds economic infrastructure are
concentrated in coastal regions. Hence, a
moderate rise in sea level will have
destroying effects on our population and
economics
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Possible Effects of Global Warming
Weather extremes. Prolonged heat
waves & droughts would occur more
frequently. Hurricanes & typhoons
would occur more frequently
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Possible Effects of Global Warming
Threats to human health. Supplies of food
& fresh water would be disrupted.
Diseases patterns would be altered
spread of diseases like malaria,
encephalitis, yellow fever, dengue fever &
other insect-borne diseases to temperate
areas
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Solutions to slow Global
Warming Use energy more efficiently. Natural gas is
a more efficient & cleaner fuel (emits
CO2 as coal)
Halting deforestation
Switching to Earth-sustaining agriculture
Slowing population growth
Removing CO2 from exhaust gases
Planting & tending trees
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Solutions to slow Global
Warming Available methods can remove only ~30%
of the CO2 from exhaust gas & would
double the cost of electricity
Each of us need to plant & tend 1,000
trees every year to absorb CO2 we put into
the atmosphere
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Solutions to slow Global
Warming - International Efforts The UNEP and WMO set up the IPCC
(Intergovernmental Panel on Climate
Change) in 1988 for assessing the
effects of climatic change & evaluating
strategies to deal with global warming
Kyoto Protocol in December 1997 called
for the industrialized nations to reduce
average CO2 emission over the period
2008-2012 to ~5% below 1990 levels
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Solutions to slow Global
Warming - International Efforts The Kyoto Protocol initially covers 3 GH
gases: CO2, methane and nitrous oxide.
It also contains the elements of
international trading of GH gas emissions
(which help ensure the lowest-cost way for
reduction of GH gases emission).
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Solution
Slow down
Global Warming
- International
Efforts
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