|
Climate Change - Introduction
Climate Change is increasingly becoming an
important consideration of our lives. Scientists believe that there are
evidences all around us that the Earth's climate has been undergoing
noticeable changes, largely attributed to anthropogenic activities (human
activities providing changes in climate additional to the natural climate
variability), particularly the industrial activities that commenced with
the industrial revolution of the 1700-1800s in certain parts of the World.
Scientists believe that human activities
result in the accumulation of greenhouse gases which trap heat and
increase the average temperature of our planet (global warming),
eventually resulting in climatic changes. Scientists (particularly the
International Panel on Climate Change (IPCC))
believe that the global temperature has increased by close to 1oC
in the last century and they believe that a further increase of between
1.1 to 6.4 oC (based on
predictions from climate models) are possible during the next century.
Global warming (i.e. increase in Earth's
average temperature) could lead to sea level rises, natural disasters - the
storms/flooding, the hurricanes, drought, wildlife extinction, water
pollution etc.
|
International Day of Climate Action -
October 24, 2009
Uppsala
Glacier in Argentina in 1928 (top)
and 2004 (bottom)
(Source:
Greenpeace)
|
|
|
What is Climate Change?
Weather is the state or condition of
the atmosphere at a given time and place measured in terms of the
atmospheric variables (i.e. temperature, humidity, air pressure, moisture,
wind, cloudiness, precipitation (rainfall and snow) and sunshine).
Weather changes from hour-to-hour, day-to-day, and season-to-season. The
changes occur with the movement of air over the Earth surface and the
resultant redistribution of heat and moisture. Climate is the
average and/or the extremes (minimum and maximum) of the atmospheric
variables over a time period (a decade or longer) for a given location.
Climate is the expected, while weather is what you get. Weather changes
rapidly, however, past data sets are used to estimate the climate of a
particular location for a time period (a decade or longer).
Climate
Change,
at a location,
is
the
observed differences in
the averages and extreme values of the atmospheric variables when computed
over two or more time periods
(each time period being about a decade or longer) at
the said location. If the
climate is to be constant, there should not be observed
differences in atmospheric variables observed in a point A between the
time period 1932 and 1942 and another time period 1952 and 1962. Climate
change represents a shift (upwards or downwards) in the magnitude of the
atmospheric variables (temperature, precipitation etc) from the long
established pattern for a given location.
Several natural causes
can lead to variability in climate. Climate variability due to natural
causes, however, seems to even out over time (see IPCC graph of temperature variability below). However,
several other human
activities identified as causing climate change or enhancing the impacts of the natural
climate change causes has been identified by the scientific reports to
have caused substantial changes to our climate. As evident in the IPCC
graph below, temperature seems to have risen by 4oC since the beginning of
the industrial age. This increment is believed to be result from changes
from human activities.
To understand how our climate is changing a body, the
International Panel on Climate Change (IPCC) was set up in 1989
by two United Nations organizations: the
World
Meteorological Organization (WMO) and the
United
Nations Environmental Programme (UNEP). IPCC is a scientific
body created with the mandate to provide the world with a clear scientific view
on the current state of climate change and its potential environmental and
socio-economic consequences. IPCC does not conduct any research nor does
it monitor climate related data or parameters. IPCC reviews and assesses
the most recent scientific, technical and socio-economic information
produced worldwide relevant to the understanding of climate change.
Thousands of scientists from all over the world contribute to the work of
the IPCC on a voluntary basis.
Variations of the Earth's surface
temperature: year 1000 to 2100 (Source:
IPCC -
Climate Change 2001 Synthesis Report)
|
