L2 Global Warming

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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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IPCC

Atmospheric levels of GH gases have

risen in recent decades

It include:

CO2,

methane,

nitrous oxide and

CFCs

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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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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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IPCC

Recent IPCC report mentioned that >90%

probable of fossil fuel burning explained

the warming

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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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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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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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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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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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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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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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~ 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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Weather extremes. Prolonged heat

waves & droughts would occur more

frequently. Hurricanes & typhoons

would occur more frequently

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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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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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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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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

L2 Global Warming

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