Global warming is the increase
in the average temperature of the earth's near-surface air and oceans since the
mid 20th century. The generally accepted theory about global warming is that
the release of greenhouse gases from the burning fossil fuel and from land-use
is responsible for the recent temperature rise.
The increase of certain gases in the atmosphere trap energy which would
otherwise escape into space. These gases called greenhouse gases include carbon
dioxide, methane, nitrous oxide, chloroflourocarbons and ozone in the lower
atmosphere. Many natural and man-made gases contribute to the greenhouse effect
that warms the earth's surface. Of all those, the increasing concentration of
atmospheric carbon dioxide is the most likely cause. When more heat is trapped
in the atmosphere, this makes the earth hotter.
The Earth has an umbrella of gas to protect it from the dangerous
ultraviolet radiation of the sun. This umbrella is known as the Ozone layer.
Unfortunately the pollutants and chemicals can destroy the ozone upsetting the
balance in the almosphere. When this happens the ozone layer is depleted and
the amount of ultraviolet rays reaching the earth's surface increases. As a result of human activities like smoke from
factories and vehicles being emitted, the composition of the atmosphere has
changed and ozone layer is now under threat. Recent satellite pictures have
shown quite clearly that there is a hole appearing in the ozone layer over the
Antarctic Pole. More UV rediation reaching the Earth can affect human health by
causing diseases like cancer and various eye-disorders.
As we know that 'greenhouse effect' and 'ozone depletion' results in
global warming we have to act promptly to check the causes leading to them. For
this human activities like burning of fossil fuels have to be replaced by
harmless methods. Planting plenty of trees can also help to a certain extent to
reduce pollution and global warming.