Saturday, May 21, 2011

Climatic Changes



            Climate basically includes changes in temperature, humidity, atmospheric pressure, wind, precipitation of that place from a long period of time, whereas weather is the present condition of these elements.  And we all know that climate is changing from place to place, since climate is affected by the latitude, terrain, altitude and the nearby water bodies. Therefore, we can say that climate is a prediction made by observing the weather of a place for a long period of time; these predictions of climate, are very important to human life because the distribution of natural resources like forest/ vegetation depends on the climatic factors. Therefore, even a slight change in the climate can influence human life at a greater degree.
             Climatic changes are long term changes in the statistical distribution of weather patterns over period of time that range from decades to millions of years. The United Nations framework conversion on climatic changes defines climatic changes as “A change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods”.  Climatic changes occur mainly due to the human behaviors that destroy the environment. Other than that, variation of solar radiation, deviation in the earth orbit, mountain building and continental drift contribute to the present undesirable climatic changes like extreme weather conditions.
             As I mentioned, the most undesirable climatic changes are due to the human behaviors that cause major environmental issues, such like emission of CO2 from fossil fuel combustion which lead to global warming.  When the average temperature of the earth’s nearby surface air and ocean is increasing causing a high annual temperature and other climatic changes such like change in precipitation due to the high evaporation of surface water. 
Not only human behavior cause climatic changes. Uncontrollable factors like variation of solar radiation cause changes in climate by affecting the global warming via cycle sunspot activity.  Another factor is the orbital variation. Seasonal distribution of earth is mainly due to the rotation of the earth in current orbit, a slight change of the earth’s orbit can induce a large change in sunlight that reach earth surface and cause seasonal changes on earth. Variation of earth’s orbit can be due to
1.       Change in tilt angle of earth’s axis of rotation
2.       Precession of earth axis
3.       Combination of above phenomena.
Other than these uncontrollable factors, volcanism which causes a cooling by partially blocking the solar radiation that receive by earth surface, plate tectonics (Building mountains, Continental drift) and ocean variations  also cause climatic changes where position of continent affect the geometry of the ocean and thereby influences the patterns of ocean circulation which helps to transfer heat around the world.
             Even though we got interested in climatic changes recently, changes in climate are not a new thing for earth, since they occur throughout the history of earth. Early scientists thought that climate changes occur slowly and that they cannot be seen during human life time.  They thought that outside forces, ranging from human activities cannot make a permanent change in the atmosphere, since earth atmosphere is so vast and it would automatically drift back to normal state.  With the increasing population, human influence on environment is so high and rapid so that changes have no more time to drift back to the normal state. Therefore, climatic changes are rapid and can be seen in naked eye. And these changes are not like early climatic changes; they are harmful for human life. Whereas these rapid changes in climate can incur health problems like water bone diseases due to undesirable precipitation causing floods. And it would introduce climatic sensitive vector bone diseases like “Dengue” (commonly found in Sri Lanka). And climate stress and the shifting of animal population would create conditions for the spread of certain infections, diseases from animal to human. Not only in health care, 
modern unfavorable climatic changes have an impact on the world economy, like the undesirable changes like heavy precipitation, long term droughts. Tornadoes, cyclones destroy agriculture lands and living places thus creating problems that take much time to recover.