1. INTRODUCTION
Our earth daily absorbs large quantity of solar energy from the sun. Most of the
energy is radiated back to atmosphere by the earth, and this process maintains the
balance of heat energy on the earth. There are many gases present in the atmosphere,
but only carbon dioxide and water vapour absorb this infrared radiation of the earth
strongly and effectively block the radiation of energy back to the atmosphere.
However a considerable part of it is re-emitted to the earth’s surface and consequently
the earth’s surface gets headed up. This increase in temperature of the earth is called
the green-house effect. Global warming is defined as the release of green house gases
into the air that trap heat on the earth, causing for warmer temperatures. Global
warming is affecting the earth a lot, and it is affecting it fast too. The greenhouse
effect is only troublesome when it gets too strong and warms things too much. The
people of industrialized nations have extracted Earth’s vast buried stores of fossil
fuels and burned them. All those extra greenhouse gases mean more and more solar
energy is being trapped in the atmosphere, exacerbating the greenhouse effect and
making things warmer. This decade has been the hottest decade in centuries (Stuart,
2005). Because of this the polar ice caps are melting, and it could change the flow of
the North Atlantic Current. The change in flow could cause immeasurable effects to
the Earth, and could change the weather that occurs on the earth dramatically.
According to the IPP 2001 report, the Earth’s surface has warmed by about 1 degree
Fahrenheit, and that is the biggest it has raised in centuries (Stuart, 2005). The hotter
atmosphere on the earth causes the ocean temperature to rise, and coincidently
hurricanes get more power from warmer waters. Not only does global warming
affects the earths weather patterns, it also affect its wildlife.

2. 2. Global warming
2.1 Contributors to global warming
A majority of scientists have concluded that human activities are responsible for most
global warming. Human activities contribute to global warming by enhancing Earth’s
natural greenhouse effect. The greenhouse effect warms Earth’s surface through a
complex process involving sunlight, gases, and particles in the atmosphere. Gases that
trap heat in the atmosphere are known as greenhouse gases. Global atmospheric
concentrations of carbon dioxide, methane and nitrous oxide have increased markedly
as a result of human activities since 1750 and now far exceed pre-industrial values
determined from ice cores spanning many thousands of years. The global increases in
carbon dioxide concentration are due primarily to fossil fuel use and land-use change.
Source: http://www.koshland-science-museum.org/exhibitgcc/images/causes03a.gif

3. 2.1.1 Natural causes
The Sun is the only source of energy for the functioning of the Earth’s climate system,
any changes in solar output may lead to climate change and specifically global
warming. It is predicted that a change in solar output by only 1% per century may
change the average temperature of the planet by 0.5 to 1.0 Celsius. Changes in the
shape of the Earth’s orbit around the sun alter the total amount of solar energy
received by the planet. This would also affect the planet’s temperature. Volcanic
activity is yet another significant contributor to variations of Earth’s mean
temperature. The sun, water vapour and volcanism are far more powerful agents of
change in climate than carbon dioxide emissions. The world’s natural wetlands
produce more greenhouse gases annually than all human sources combined.
Greenhouse gases and solar forcing affect temperatures in different ways. While both
increased solar activity and increased greenhouse gases are expected to warm the
lowest portion of Earth’s atmosphere, an increase in solar activity should warm the
second major layer of the atmosphere (stratosphere) while an increase in greenhouse
gases should cool the stratosphere. The oceans play an important role in determining
the atmospheric concentration of carbon dioxide. Carbon dioxide gas in the
atmosphere and dissolved in the ocean surface reach a balance. Changes in ocean
circulation, chemistry, and biology have shifted this balance in the past. Such changes
may affect climate by slowly moving carbon dioxide into or out of the atmosphere.

4. The above graph shows the departure from the long-term average, of average global
temperatures, in degrees Fahrenheit, since 1880. (Source: EPA)
2.1.2 Human activities
The main human activities that contribute to global warming are the burning of fossil
fuels (coal, oil, and natural gas) and the clearing of land. The focal point of this cause
is the generation of energy for use both in industry and commercial/ private sector.
Fossil fuel combustion is especially heavily used as a source of energy for industry.
However, we have burned these fuels faster than the rate at which it was removed by
the early tropical forests, in other words very large amounts of carbon dioxide is
released at a very high rate and the nature is unable to remove it in good time. This
leads to the accumulation of extra carbon in the atmosphere and consequently to
global warming. For example, burning occurs in automobiles, in factories, and in
electronic power plants that provide energy for houses and office buildings as well as
deforestation and various agricultural and industrial practices are altering the
composition of the atmosphere and contributing to climate change. These human

5. activities have led to increased atmospheric concentrations of a number of
greenhouse gases, including carbon dioxide, methane, nitrous oxide,
chlorofluorocarbons, and ozone in the lower part of the atmosphere. Carbon dioxide is
produced when coal, oil, and natural gases (fossil fuels) are burned to produce energy
used for transportation, manufacturing, heating, cooling, electricity generation, and
other application. There are some other industry-related activities usually called
industrial processes which are also significant sources of greenhouse gases. The
products whose manufacturing causes emission of these gases include cement,
minerals, chemicals, metals. Many activities related to industrial processes use large
amounts of energy and thus produce significant amounts of greenhouse gas emissions
through fossil fuel combustion.
2.1.3 Land use
Land use changes for example clearing land for logging, ranching, and agriculture
lead to carbon dioxide emissions. Vegetable contains carbon that is released as carbon
dioxide when the vegetation decays or burns. Normally, lost vegetation would be
replaced by re-growth with little or no net emission of carbon dioxide. However, over
the past several hundred years, deforestation and other land use changes in many
countries have contributed substantially to atmospheric carbon dioxide increases.
Methane (natural gas) is the second most important of the greenhouse gases resulting
from human activities. It is produced by rice cultivation, cattle and sheep ranching,
and by decaying material in landfills. Methane is also emitted during coal mining and
oil drilling, and by leaky gas pipelines. Nitrous oxide is produced by various
agricultural and industrial practices. When land is cleared for expansion of human
settlements or for timber sales, a cocktail of pollution is released as part of this

6. process and the main greenhouse gas emitted is carbon dioxide. Most importantly is
tropical deforestation especially by forest fires and alongside other pollutants causes
the release of carbon dioxide. The main greenhouse emitted as a result of waste
management is methane, with some small amounts of nitrous oxide. Tropical
rainforests play a very important role in regulating global and regional climate
patterns. An extremely important service provided by the rainforests is the removal of
carbon dioxide from the atmosphere by photosynthesis. It acts as a pollution or carbon
dioxide sink and storage. Deforestation leads to release of carbon dioxide from the
trees back to the atmosphere, release of carbon stores held in soil into the atmosphere
and destruction of forests as carbon sinks for future carbon dioxide removal and all of
these will further contribute to the global warming effect.

7. 2.2 Impact of global warming
2.2.1 World
The impact of global warming is far greater than just increasing temperatures.
Warming modifies rainfall patterns, amplifies coastal erosion, lengthens the growing
season on some regions, melts ice caps and glaciers, and alters the ranges of some
infectious diseases. The IPCC has concluded that global temperatures will likely rise
from 1.2 to 6.5 degrees Celsius by the end of the century depending on different
scenarios regarding greenhouse gas emission. Rainfall patterns will continue to
change around the world. In general, global warming should accelerate the
hydrological cycle. Warmer air cause more water to evaporate. A warmer atmosphere
can hold more water vapour, so more water is available to fall back to Earth when it
rains or snows. As a result, extreme precipitation events should become more frequent
and intense leading to worse flooding. In addition, increased evaporation in some
regions will lead to drier conditions, with a higher probability of drought. Ice is
melting worldwide especially at the Earth’s poles. This includes mountain glaciers,
ice sheets covering West Antarctica and Greenland, and Arctic sea ice. For more
places, global warming will result in more frequent hot days and fewer cool days with
the greatest warming occurring over land. Most importantly, global warming will
affect on ecosystems, the plants and animals that co-exists in particular climate zone,
both on land and in the ocean. Warmer temperatures have already shifted the growing
season in many parts of the world. This change in the growing season affects the
broader ecosystem. Migrating animals have to start seeking food sources earlier. The
shift in seasons may cause the lifecycles of pollinators to be out of synch with
flowering plants and trees. This mismatch can limit the ability of both pollinators and

8. plants to survive and reproduce which would reduce food availability throughout the
food chain.