Global warming and global dimming are becoming common topics of discussion in the world today. The rising speculations about where the world’s environment is heading are worrying. This is felt most in the sudden rise and fall in temperatures and unexpected climate changes around the world. These effects are mostly attributable to the greenhouse gases whose concentration in the atmosphere is increasing daily. The greenhouse effect is a naturally occurring process, in which emissions of infrared radiation by the atmosphere warms the earth’s surface. This principle is based on the ability of the atmosphere to capture and recycle energy emitted by the earth’s surface. The earth’s average temperature of 14*C would be about 19*C in the absence of the greenhouse effect. Mechanism The earth receives energy from the sun inform of radiation. It then reflects about 30% of this energy while the remaining 70% is absorbed hence warming the land, atmosphere and ocean. In order for the earth not to rapidly cool and heat up, a steady state has to be maintained. This is achieved by the absorbed solar energy being balanced by the energy radiated back to space in form of infrared wavelengths. These infrared radiations that are absorbed in the atmosphere by greenhouse gases and clouds do not easily escape directly into the outer space. The radiations instead bond with particular gases. Greenhouse Gases In the atmosphere gases like Oxygen, Nitrogen and Argon do not interact with, and cannot absorb or emit infrared radiations. The dominant absorbers are water, Carbon dioxide and Ozone which have infrared emitting molecules. Other absorbers are Methane, nitrous oxide and chlorofluorocarbons. Global Warming Global warming, a recent warming of the earth’s lower atmosphere is believed to be a result of an enhanced greenhouse effect due to increased concentration of greenhouse gases in the atmosphere. Advances in human activities are believed to have started global warming and this took effect at the start of the industrial era. This was when a lot of waste gases started getting released into the atmosphere. The effects of global warming are steadily intensifying and this is seen at the North Pole where a massive meltdown of the ice is occurring. As a result of this the native White Polar bear’s existence is endangered. It is believed that if the meltdown does not cease, all the water from the melted ice will cause a great flood that will devastate the whole North Pole and the surrounding environment. Variations in solar activity are also a contributing factor. As a result of global warming, the current climate of the earth is no longer in equilibrium with the atmosphere. Global Dimming On the other hand, the effects of global dimming which is the reduction of the amount of radiation reaching the earth’s surface are very real. The pollutants that are released into the atmosphere combine with the clouds. This makes the incoming sunlight get reflected back into space and less reaches the earth’s surface. This has interfered with the hydrological cycle hence resulting in a reduction in the process of evaporation. Clouds also intercept with the heat radiation from the sun and the earth’s surface which leads to global dimming. Effects of global dimming are evident around busy airports and places where large amounts of wood are burnt. Fossil fuels like diesel which is used in aircrafts and burnt wood, release black carbon into the air which create dark clouds. The proof of this was seen during the suspension of all flights in U.S.A after 9/11 bombings. The atmosphere became so clear and bright in contrast to the usual dark and dim appearance. Effects of global dimming can also be felt at various hours. During day time, the interception of sunlight by clouds and greenhouse gases gives a cooling effect. During night time, re-radiation of heat back to the earth’s surface slows down heat loss which leads to very warm nights. Other effects of global dimming are seen in a number of unexpected floods that have occurred around the world. Of recent places like Indonesia, England and Mozambique have been victims of these floods. Widespread droughts and famines in Africa are results of climate changes due to global dimming. This is the case with Somalia which over the years has suffered from this calamity. Ozone layer Destruction of the Ozone layer is inevitable with the increase in bonding of greenhouse gases with ozone gas in the atmosphere. The ozone layer which protects the earth and everything therewith from the harmful ultraviolet rays and radicals of the sun is slowly getting depleted. Unfortunately once destroyed the ozone layer cannot be replaced. The irony of all these sequences of events is that the areas and people, who suffer the most, do not contribute a lot to the formation of the effects of global warming and dimming. Developed countries which are releasing huge quantities of waste gases to the atmosphere do not suffer the most. Instead it is the underdeveloped countries that feel the pain due to their location and the air current movements. The only way to avoid the foreseen destruction of our world and its environment is taking alternative measures that are harmless to the ozone layer so as to combat this necessary evil. Ends
