The
problem we now face is that human
actions - particularly the
burning of fossil fuels (coal, oil and natural gas) and land clearing -
are increasing the concentrations of these gases, creating the prospect
of global climate change.
Carbon dioxide (CO2) emissions resulting from direct human activities
have
perturbed the global carbon cycle. Thus the CO2 concentration in the
atmosphere is now about 20% higher than 200 years ago. Burning of oil,
coal and natural gas, and the clearing and burning of vegetation, are
the main causes of the rise. This gas makes the biggest contribution to
the enhanced greenhouse effect (about 70%).
What is the greenhouse
effect?
The warming
effect of the Earth's atmosphere is called the greenhouse
effect. Radiation from the Sun enters the atmosphere but is prevented
from escaping back into space by greenhouse gases. These gases trap
heat because they readily absorb
infrared radiation. As the energy cannot escape, it warms up the Earth,
causing an increase in the Earth's temperature (the global warming).
greenhouse
effect - schematic figure
What is global climate
change
(global warming)?
Our climate has warmed by about 0.7°C over the last 300 years,
with
about 0.5°C of warming occurring over the last 100 years.
It is accepted that much of this change is due to an increase in the
emissions of greenhouse gases, which are created through burning fossil
fuels.
Scientific models predict that the average global temperature will rise
by a further 3°C by the next century unless change takes place
now.
With a rising in global temperatures, the ice caps in the Arctic and
Antarctic waters have already begun melting, which is leading to sea
level rises.
The resultant effect on human life and the natural environment could be
devastating, with rising sea levels likely to submerge whole islands in
the Pacific, flood low lying areas in many countries and inevitably
push entire species to extinction.
The extraction and use of fossil fuels are responsible for many of the
world's environmental problems. Much air and water pollution, soil
erosion and climate change is energy related.
To address these issues, a shift to methods of producing heat and
electricity that do not compromise the environment and the needs of
future generations is a global priority.
Why do we need renewable
energy?
Electrical energy is essential to billions of people around the world.
We are reliant on it for the simplest of things from light to read by
to water for a shower.
The conventional sources of power come from burning of fossil fuels
such as coal, gas, oil or from nuclear fuels. As there are fears of
fossil fuel shortages, as well as evidence that fossil fuels are
creating climate change and concerns about nuclear power,generation of
an alternative clean energy source is clearly of growing importance.
What is the greenhouse
gases
problem?