Global

Issues

Presentation by: Harmandeep, Thang, Safir

Global

Warming

The Fact:

4000 islands in Indonesia will drown in the upcoming years

due to rising sea levels caused by Global Warming.

9.1

What is Global Warming?

Global Warming refers to the increasing temperature of

earth's surface due to the excess heat trapped into our

atmosphere. This takes place due to enhanced green house

effect.

What is Greenhouse effect?

The phenomenon whereby the earth's atmosphere traps solar radiation, caused by the presence in the atmosphere

of gases such as carbon dioxide and methane that allow

incoming sunlight to pass through but absorb heat radiated

back from the earth's surface. This keeps the Earth warm

and a nice place to live in, keeping us all happy.

“Enhanced” greenhouse effect

These days, human activities produce too much greenhouse gases

that makes the earth’s atmosphere thicker, making it impossible for

the Sun rays to reflect back into the atmosphere. Hence, the Sun rays get stuck into the earth's atmosphere, making it too hot to live in. This

is called Enhanced Greenhouse Effect and is what's

causing Global Warming.

Greenhouse Gases

- Carbon-dioxide

- Methane

- Nitrous Oxide

- Chlorofluorocarbons

- Surface Ozone

Carbon Dioxide- Produced by burning fossil fuels such as

gas, petrol, aviation petrol, diesel and oil

Methane

- Produced when you burp or fart.

- Twenty –one times more effective

than carbon dioxide in blocking the

escape of radiant heat.

Nitrous Oxide- Produced from burning forests, car

exhaust, jet fuel and artificial fertilizers.

Chlorofluorocarbons (CFCs)

- Invented in 1920s.

- Were found in aerosol spray cans and as coolant gases on refrigerators.

- Non-poisonous.

- Odourless.

- Were once called ‘wonder chemicals’.

- Stable and cheap to produce.

Surface Ozone- Generated as a part of photochemical smog.

- Produced by the action of sunlight on motor vehicle and industrial pollution.

Australian greenhouse gas

production

Carbon dioxide

Methane

Nitrous Oxide

Other

Evidence of global warming

#1- Glaciers have been melting.

Evidence of global warming

#2- Icebergs are breaking off.

Evidence of global warming

#3- Ice sheet in Greenland is getting thinner.

Evidence of global warming

#4- Coral reefs in the Caribbean are now permanently bleached.

Evidence of global warming

#5- Alpine plant species has fallen.

Evidence of global warming

#6- Snowgums in Australia have shifted 40 meters up the mountain.

El Niño effect

El Niño effect occurs in which trade winds weaken or

reverse, allowing warmer water to move towards the

west coast of South America around Christmas time.

The result is that Australia experiences drought, and

South America experiences increased rainfall.

9.3

Ozone Layer

What is Ozone?

Ozone is naturally occurring form of oxygen, each

molecule comprising three atoms.

Ozone Layer

Ozone is created when UV light splits oxygen molecules into single

atoms. These single oxygen atoms then join other oxygen

molecules to form triplets of oxygen atoms, or ozone molecules.

UV light also splits ozone molecules, so ozone is continually being

created and destroyed, with UV light being absorbed in the process . The region, in which ozone is thinly distributed is referred

to as the ozone layer.

Dobson Unit

- Measures the thickness of the ozone layer.

- A value of less than 220 DU is considered to be an

ozone hole.

- If all the ozone molecules in the ozone layer were

brought to ground level, it would form a sheet

averaging only 500 DU(5mm) thick.

The future:

Kyoto Protocol

- Formed in 1987 to stop manufacturing of CFCs.

- One hundred nations signed up.

- The agreement is expected to bring the ozone

levels back to normal by 2045.

9.3

Nuclear Radiation

Radiation and

Radioactivity

- An element whose atoms emit nuclear

radiation is said to be radioactive.

- Example: Uranium.

Atoms and Isotopes

- Isotopes are atoms of the same element that have

different numbers of neutrons in their nuclei.

- A radioactive isotope is called a radioisotope.

- When referring to a radioisotope, often just its mass number is given.

- Example: Lithium.

Types of Nuclear Radiation

- Alpha radiation

- Beta radiation

- Gamma radiation

Alpha Radiation

- The thrown out cluster from

radioactive nuclei is known as alpha

particle.

- Its done so to make the nuclei smallerand more stable.

- Alpha particles move at speeds of

up to one-tenth of the speed of light.

- Alpha particles are stopped by a

thick sheet of paper or human skin.

Beta Radiation

- When there is an imbalance of neutrons and protons in a

nucleus, a neutron may change into a proton and an electron. The newly created electron is called a beta particle.

- Beta radiation can be blocked using aluminum sheet of 1mm.

Gamma Radiation

- Sometimes when an alpha particle or beta particle is

emitted from nucleus, the new nucleus is still unstable

and emits extra energy in the form of gamma ray to become even more stable.

- Gamma rays can only be blocked by a thick piece of

lead or concrete.

Half-Life- Half-life is the time taken for half the atoms in a

sample to decay.

- Example: quantity of radon-222 halves every four

days.

Carbon Dating

- Used to date back dead organisms.

- It is done by comparing the amounts of carbon-14 and

carbon-12 in the organism.

Uses of Nuclear Radiation

#1- Used in radiotherapy to treat cancer.

Uses of Nuclear Radiation

#2- Used to detect thickness of paper.

Uses of Nuclear Radiation

#3- Used in hospitals to sterilize

medical equipment.

9.4 Nuclear Energy

Nuclear Fission

- Its when uranium hits the

neutron and as a result the

neutron becomes very

unstable and that produces

heat and energy.

Nuclear Fusion

- Its when tritium and deuterium combine

together releasing neutron. It produces

energy and heat.

Other Alternatives

#1- Solar Energy.

Other Alternatives

#2- Wind Energy.

Other Alternatives

#3- Geothermal Energy.

#1- Think Green

#2- Do Green

#3- Share Green

Save The Earth