Understanding Climate Change

- Climate change is one of the big concerns of our time as we have learned that it has adverse consequences on our atmosphere and the environment. What really is climate change? What are the causes of climate change? How does climate change affect our lives? We shall get answers to these questions and other similar questions on this page and other pages on this website.

What is Climate Change?

We shall start by defining weather, climate and then 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 in weather occur with the movement of air over the earth surface and the resultant redistribution of heat and moisture.

Climate , on the other hand, 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. It is an established pattern of the values of the atmospheric variables, which has been derived from several years of collecting weather information at the target location. As mentioned earlier, weather changes rapidly (hourly or daily basis) but past data records were used to estimate the climate of a particular location for a time period (a decade or longer). To easily remember the difference between weather and climate, it is good to consider climate is the expected, while weather is what you get.

Climate Change at a location, is the observed differences in the averages and/or 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 target 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 - 1942 and another time period 1952 - 1962. If the average temperature of location "A" over a decade (1932-1942) is 23oC and the average temperature of the same location "A" for another decade (1952-1962) is 23.8oC, then the location has witnessed a change in climate as there has been a temperature increase of 0.8oC.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. The shift is established by considering large volume of data collected throughtout the period of interest.

What is the difference between Climate Change and Global Warming?

The increase in average global temperature, as noticed in our example above, causes the warming up of the planet. The warming up of the planet is what is referred to as Global Warming while climate change, as defined above, refers to the difference in the averages or the extremes of atmospheric variables of two or more periods of time.

International Panel on Climate Change (IPCC)

To understand how our climate is changing, an organization called 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 but rather 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.

From their studies, IPCC have found out 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 is possible during the next century, based on predictions from climate models.

Causes of Climate Change

Climate change is caused by increase in the global energy balance (GEB) which is the difference between the energy the earth surface receives from the sun and the energy the earth surface reflects back to space. The change in the GEB is caused by internal and external climate forcing processes. External processes are from outside the earth (e.g. variations in the amount of energy received from the sun and variations in the earth’s orbit around the sun) while internal processes are from within the earth (e.g. effects of oceans, continental drift, atmospheric processes, water cycle, clouds, ice and snow, land surfaces, volcanic eruptions and man-made processes (mainly industrial and agricultural)). The external climate forcing processes and the internal climate forcing processes except the man-made processes are grouped together as natural causes of climate change while the man-made processes are anthropogenic or human causes of climate change. The natural causes are believed to even out eventually and are not considered to be responsible for climate change. However, the anthropogenic causes are believed to be the main causes of the change in climate from one period to the other. For more information on the causes of climate change, readers are requested to read: Causes of Climate Change on this website.

Human influence on the climate started with the industrial revolution of the 1700-1800s in certain parts of the World. The human industrial activities generate greenhouse gases which trap heat and increase the average temperature of our planet (i.e. warms up our planet) and produce periodic changes in climate. Our industries use fossil fuels (Coal, Oil/petroleum and Gas) to generate energy for their processes. These fuels are known to be dirty fuels that release the GHGs to the atmosphere. Some of these greenhouse gases are: Carbon Dioxide (CO2); Methane (CH4); Nitrous Oxide (N2O); Hydrofluorocarbons (HFCs); Perfluorocarbons (PFCs); and Sulphur Hexafluoride (SF6). Also responsible for the generation of the GHGs is human's agricultural practices causing the release of substantial amount of methane (CH4) to the environment. For more information on the human influence on climate change, readers are encouraged to read: Human Contributions to Climate Change on this website

The impact of climate change on our atmosphere and our environment include: Winds, tornadoes and hurricanes are becoming stronger than before resulting in loss of lives and properties; glacier is melting fast and there is decline in snow cover leading to less fresh water for drinking and danger for animals of snow habitat (e.g. polar bears); rising sea levels and flooding; decrease in water levels in ponds, lakes and other water bodies; increasing precipitation; changes in the timing of lake and river freeze-up/break-up; and in permafrost regions, thawing of permafrost. For more information on the impact of climate change, readers are encouraged to read: Evidences and Effects of Climate Change on this website

Variations of earth's temperature

Variations of the earth's surface temperature: year 1000 to 2100 (Source: IPCC - Climate Change 2001 Synthesis Report)

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