ESD02. Global Env.tal Problems-1

8/19/2019 ESD02. Global Env.tal Problems-1

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GLOBAL ENVIRONMENTAL PROBLEMSPart-1


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Global Environmental Problems

Occurrence of these problems may be local in nature, but its effects /impacts / damages may not be limited to local or regional level; but these

are recorded across the globe. e.g.

Global warming,

Acid rain marine pollution

Trans-boundary movement of hazardous waste, etc.

The occurrence of these problems is not local in nature. These problems

may occur throughout the globe in various countries.

e.g. deforestation, desertification, etc.


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Types of Global Environmental Problems

Global Warming

Ozone layer depletion

Acid Rains or Acid Deposition

Loss of bio-diversity

Trans-boundary movement of hazardous wastes and chemicals

Deforestation

Desertification

Marine pollution


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Issues – Global Environmental Problems

Have long-term effects on people or societies:

Are either impossible or difficult to remove / reverse in short time duration

May require international efforts for solution


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Global Warming

Green House Gases

Responsible for

Green House Effect


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Total Co2 Emssions by country


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Enhanced Green House Effect

Various Green House Gases in

Atmosphere

Human Activities – release CO2 &other air pollution

Collection in the atmosphere

Acts like a thick blanket

Traps the Sun’s heat

Ultimately, Planet warms up


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Phenomenon

Global Warming - Increase in Earth’s average temperature (Atmosphere &

Oceans)

According to certain observations in the last century, Global surface

temperature has risen by

• 0.6°C (plus or minus 0.2°C) since the late-19th century, and

• about 0.4°F (0.2 to 0.3°C) over the past 25 years*

It is not a uniform phenomenon and has considerable uncertainty

Regarding

Extent of temperature rise,

Scale,

Timing,

Regional distribution, etc.

Note: * - Source: http://lwf.ncdc.noaa.gov/oa/climate/globalwarming.html


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Gases responsible for Global Warming

Green House Gases (GHGs):

Carbon Dioxide

Methane

Nitrous Oxide

Choro-fluoro-carbons


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GLOBAL WARMING – Consequences

Rising temperature of atmosphere and earth’s surface

Melting of ice in the polar regions

Rise in sea levels causing coastal flooding

Change in regional climate

Alter forests, crop yields and water supplies

Ecosystem

Human health

Expansion of deserts into rangelands, forest areas, agricultural areas


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Illustrations showing signs of Global Warming

Garhwal Himalayas, India

Glacial retreat at record pace. The Dokriani

Barnak Glacier retreated 66 ft (20.1 m) in

1998 despite a severe winter. The Gangorti

Glacier is retreating 98 ft (29.9 m) per year.

At this rate scientists predict the loss of allcentral and eastern Himalayan glaciers by

2035. (Reference: 1998. Himalayan glacier

backing off. Science 281:1277).

Source: http://earthobservatory.nasa.gov/Newsroom/NasaNews/2002/200205299370.html


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Ozone Layer Depletion

Ozone – one of the most important

constituents of the atmosphere Form of

Oxygen

Ozone shield:

Stratosphere

It absorbs the harmful ultra violet (UV)

radiation from the sun

Ozone layer is critical for the survival of

most life present on the Earth

Source: www.ns.ec.gc.ca/udo/ozone.html


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Destruction of Catalytic Ozone:

O3 + X → XO + O2

XO + O3 → X + 2O2

2O3 → 2O2

‘X’ chemical triggers ‘Chain Reaction’

Estimated says that single chlorine atom can destroy, more than

100,000 Ozone molecules before it is eliminated by other

reactions.

Ozone Layer Depletion


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Catalyst responsible for Ozone layer depletion

Important catalysts in Stratosphere:

Nitric Oxide (NO), hydroxyl (OH), Chlorine (Cl2), Bromine (Br)

XO –NO2, H2O, ClO and BrO

Sources of catalytic agents:

Natural phenomenon & Human activities


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Ozone Layer Depletion – Causes

Due to human activities:

1960s: Supersonic transport airplane (nitrogen oxides–

Harold Johnston)

1970s: Space shuttles (chlorine)

1974: Aerosol spray cans (CFCs – Molina and Rowland)

Nuclear test explosions & Bromine bombs Currently: Supersonic aircraft ‘High Speed Civil Transport’

Natural factors:

Supernova (stellar explosion)

Meteors and asteroids

Solar flares emit energetic particles that peirce the upper

layers of the ozonosphere

Its impact is very

small and hencethreat to life is also

less.


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Characteristics of Catalytic agents


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Consequences or Effects

Affects heat balance on the earth, which may lead to modification ofclimate.

Increases the UV radiation on the surface of the earth affecting the

organisms adversely: sunburns, snow-blindness, eye damage, cataracts,

ageing, wrinkling of skin, damage to immune system and skin cancer.

Affects several plants species – slow down of photosynthesis, delaying

germination, reduction in leaf size, stunted growth, poor seed quality,

increased susceptibility to weeds, pests etc.

Can depress photosynthesis in marine algae and can kill several species.

As it can penetrate 10 to 20m deep in water, can upset marine ecology

and lower fish yield.


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Illustration showing signs of Ozone layer Depletion

Ozone Hole over Antarctica:

These images from the Total Ozone

Mapping Spectrometer (TOMS) show

the progressive depletion of ozone

over Antarctica from 1979 to 1999.

This "ozone hole" area:

September 1996 - 10.0 million square

miles

September 1998 - 10.5 million square

miles

It develops each year between late

August and early October.

Regions with higher levels of ozone are

shown in red


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THANK YOU

ESD02. Global Env.tal Problems-1

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