Global warming and climate change have been greatly debated by scientists around the globe for several years. The main issues of contention in regard to climate change have been the major causes. Research has been continuously done to ascertain the extent to which both natural and man-made causes are significant. Some of the natural causes that have been found to contribute to climate change include volcanic eruptions, sun spot activity, and change in earth’s orbit among others (Wolff, 2014). Scientists have however, equivocally agreed that the main cause of climate change is associated with anthropogenic factors, which include burning of fossil fuels, aerosol emission, and land use change.
In everyday human activities, greenhouse gases are released into the atmosphere. The increase in industrialization in many parts of the world has raised the amount of these gases released into the atmosphere. Presence of greenhouse gases in the atmosphere traps the earth’s outgoing long wave radiation leading to increased temperatures in the lower part of the atmosphere (Wolff, 2014). The amount of carbon dioxide and methane has significantly increased in the last few decades and many parts of the world have recorded high maximum and minimum temperatures. Although water vapor is an abundant green house gas in the atmosphere, its short life span in the atmosphere makes is less effective in causing climate change.
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Carbon dioxide is one of the effective greenhouse gases in the atmosphere. Its existence in large quantities traps the long wave radiation and subsequently leads to increase in the average surface temperature. Human activities such as burning of fossil fuels cause emission of carbon dioxide. Many motor vehicles use petrol and combustion of these fuels results on carbon dioxide. In urban areas where traffic congestion is experienced, the amount of carbon dioxide is relatively high (Solomon, 2007). Although it may not be released in voluminous quantities, its ability to stay long in the atmosphere makes it the most effective green house gas. The emission of carbon dioxide into the atmosphere by human since the beginning of industrialization has increased by 30%.
Methane is another green house gas that is highly generated by human activities such as agriculture and organic matter decomposition. It is also emitted by ruminants such as cows during digestion. Although it is stronger than carbon dioxide since it has a high capacity to absorb heat, its little amount in the atmosphere makes it the second most effective gas in the atmosphere (Solomon, 2007).
Nitrous oxide is also another significant green house gas that is largely emitted from agricultural activities such as use of fertilizers as well as combustion of fossil fuels. Other man-made compounds such as Chlorofluorocarbons have been found to be dangerous and have been regulated as a result of its impact on the Ozone layer.
A report by IPCC (2007) shows that the concentration of carbon dioxide in the atmosphere has rise by about 109 ppmv since the beginning of the 21st century (Solomon, 2007). Annual variations however, exist as a result of oxidation and photosynthesis annual cycles. Similarly, methane gas has increased by more that 1000ppbv over the same period. It has also been found that the average warming as a result of greenhouse effect since 1850 to 2000 is about 2.5Wm2 with 60 % of this being contributed by carbon dioxide and 25% being contributed by Methane. It is expected that a warming effect of 4 W/m2 will be observed if the amount of carbon dioxide doubles its pre-industrial level (Solomon, 2007).
Aerosols released from human activities have profound effects in climate change as they are responsible for absorption and scattering of long wave infrared radiation. Their existence in the atmosphere may also lead to a change in the chemical composition of clouds hence their lifetime (WMO, n.d). Humans emit aerosols to the atmosphere through agricultural activities, burning of biomass, industrial processes, and emissions from exhausts
Lastly, the land use change such as deforestation has been found to affect the albedo of the earth surface. Since the beginning of industrialization, half of land has been converted from forests to farm lands and grazing fields. An increase in surface albedo causes a cooling effect and this is characteristic of forested areas (WMO, n.d). Cleared areas have little albedo as most of the solar radiations are absorbed hence increased heating as a result of more long wave radiation being released from the earth surface.
In conclusion, anthropogenic factors are the main causes of climate change that has been felt in many parts of the world in form of increasing temperatures, increasing snow melt, and increase in sea levels among others. If no proper approach is put in place to reduce emission of green house gases into the atmosphere, the effects are going to be detrimental in the near future.
Solomon, S. (2007). IPCC (2007): Climate Change the physical science basis. American Geophysical Union, Fall Meeting 2007.
WMO(n.d). Causes of climate change. Retrieved from <https://www.wmo.int/pages/themes/climate/causes_of_climate_change.php/>
Wolff, E. (2014). Climate Change: Evidence and Causes. School Science Review , 96 (354), 17-23.