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Access the Role of Urban Areas in Climate Change

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"Access the Role of Urban Areas in Climate


Name: Rachel McCormack

Student ID: 110371361

Date of submission:19th November 2010

Tutor name: Darius Barrlett

The world in which we live is changing rapidly be it population, technology,

or, indeed, the big issue of climate change. As humans, we question this term climate

change; what is it? Climate change can be defined as "Any change in global

temperatures and precipitation over time due to variability or to human activity". As

of now, we hear a lot about this issue and its causes but, in fact, we don't really know

much about climate change. Through research carried out by various geographers,

scientists and environmentalists, one can, evidently, see that this issue of climate

change is occurring, and fast at that. Some insist that human interaction contributes to

climate change. If this is so, then most certainly the areas, in which, the most human

activity occurs, that is, the urban areas are going to be the most influential.

Climate change is, undoubtedly, a broad issue. The main cause is said to be the

accumulation of greenhouse gases within our atmosphere, which leads to a

disturbance in the greenhouse effect causing global warming. Greenhouse gases

include carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons (CFC's).

Cconcentrations of carbon dioxide in the atmosphere are naturally controlled by many

processes collectively known as the "carbon cycle". The flux of carbon between the

atmosphere and the land and oceans is regulated by natural processes, such as plant

photosynthesis. While these natural processes can absorb some of the anthropogenic

carbon dioxide emissions, it can't cope with the levels we are seeing today. Research

carried out by the National Energy Information Centre (NEIC) proves that major

greenhouse gases have increased by 25 to 30 percent, since the large scale

industrialization began over 150 years ago. During the past 20 years, three quarters of

man-made carbon dioxide were from the burning of fossil fuels. In 1850, there were

almost no record of anthropogenic emissions of carbon dioxide and atmosphere

concentrations were much lower at 280ppmv. In stark contrast, the anthropogenic

emissions and atmospheric concentration of carbon dioxide grew incredibly by the

year 2000. Anthropogenic emissions of CO2 were at an all time high, with over 6500

million metric tonnes of carbon dioxide released in the atmosphere, causing

atmospheric concentrations up to 370ppvm. One can only draw up the conclusion that

we humans in industrialized areas, such as cities, are responsible for such a

phenomenal rise in the concentration of CO2 in the atmosphere.

This brings me on to the point of how the concentration of these gases causes climate

change. Firstly, it disturbs the greenhouse effect. The green house effect occurs

naturally in our atmosphere and aids the heating of the earth's surface. This process

uses greenhouse gases, such as carbon dioxide, water vapour and methane to change

the energy balance of the earth by absorbing longwave radiation, emitted from the

surface of the earth. The greenhouse effect is an essential part of our earth, as there

Would probably be no existence of life without it. However, if the concentration of

gases in the earth rises, it will disturb the natural function of the greenhouse effect. As

the sun passes through the atmosphere, a number of processes are carried out. Some

of it is reflected back in to space by clouds (26% globally). About 19% of the energy

that is given from the sun is absorbed by gases (ozone), clouds, and particles in the

atmosphere. The remaining 55% of the solar energy passing through the Earth's

atmosphere; 4% is reflected from the surface back to space. On average, about 51% of

the Sun's radiation reaches the surface. This energy is then used in a number of

processes, including the heating of the ground surface; the melting of ice and snow

and the evaporation of water; and plant photosynthesis. If you add uncontrollable

amounts of greenhouse gases into the atmosphere, then it causes interference with

these natural processes. The main issue is the depletion of the ozone, if gases aren't

being renewed; they are trapped in the atmosphere. Gases such as fluorocarcons-12

and -11, nitrous oxide and methane, have very long survival times. This enables them

to reach the stratospheric ozone layer. If they reach this layer, this causes problems as

The harsh ultraviolet light causes decomposition of the fluorocarbons releasing

chlorine atoms that destroy the ozone layer. The ozone is important to prevent the

overheating of the earth's surface, as it allows reflected sun rays to pass out through



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