Zoology Department
Prithvi Narayan Campus, Pokhara
bhabaamatya@yahoo.com
Global warming refers to the rising global temperature. It causes climate change that is responsible for: flood; frequent and intense rain and snow; change in the normal occurrence of monsoon thereby affecting crop production; drought; land slide; vector borne diseases; more frequent tropical storms; forest fire and extinction of species due to the loss of ecological niches.
Scientists all over the world believe that global warming is caused mainly by two processes as given below:
1) Increase in the level of green house gases such as carbon dioxide (Co2), chlorofluorocarbons (CFCS), methane and water vapour due to burning of fossil fuel and deforestation.
According to Milankovitch cycle, there is a periodic change in the Earths orbit and rotation around the sun that alter solar radiation reaching the Earth and cause global warming as well as cooling.
Green house effect is the major cause of global warming. In the troposphere level of atmosphere there are gases like Co2, CFCS, methane and water vapour that allow visible light and infrared radiation from the sun to reach the earth but do not allow heat (infrared radiation) from the earth to escape out thereby increasing the temperature of the earth.
Earth faced global warming and cooling in the past, long before human evolved in the earth. However the global warming occurring at present is found to be very rapid due to excessive production of Co2. This is harmful to the natural ecosystems as they cannot adopt the fast occurring environment change thereby increasing the chance of species extinction.
Global warming directly effects the life and life cycle of organisms, glaciers on mountains, heats up sea, melts polar ice, increases the chance of forest fire, cause drought and dries up rivers, ponds and lakes.
The melting of glaciers and polar ice increase sea level. Studies have shown that the sea level has raised by 4-8 inches during the last 100 years. The rise of sea level brings coastal flooding that is dangerous to the islands.
Global warming heats the sea water and interferes with its circulation. The important circulations in the sea are: Arctic circulation, EI Nino and LA Nina. They effect climate in most parts of the earth. High temperature can slow down Arctic circulation and increase the frequency and intensity of EI Nino and LA Nina.
EI Nino causes the accumulation of warm water in the tropical pacific along the west coast of South America where as LA Nina causes the upwelling of cold water in the west coast of South America and accumulation of warm water in the east coast of Asia near Indonesia.
LA Nina causes rain and monsoon in India, Africa and North America.
In Nepal, the global warming and climate change has brought following consequences:
a) Late monsoon season affecting the crop production.
b) Insecure supply of clean water for drinking as well as aquaculture.
c) Rapid melting of glaciers has dangered the existence of temperate lakes in high altitudes.
d) High possibility of forest fire.
e) Man as well as animals are forced to live under stress due to warm climate mainly in the terai region of Nepal.
f) Warm climate has effected the life cycle of many animals as well as plants. For example, the late flowering of plants including Lali Gurans (Rhododendron).
g) Decrease in the volume of water in high altitude rivers and streams has threatened the life of coldwater fishes and other aquatic organisms.
h) Out break of diseases due to insufficient supply of water in hilly region.
i) Excessive melting of glaciers and rain has caused flooding especially in Koshi river, in the east of Nepal, affecting the life style of thousands of people and destroying land and crop fields.
j) Land slides in different parts of the country.
Fighting Global Warming:
We must act responsibly against global warming before it's too late. The following activities act against global warming:
1) Reduction in the use of fossil fuel
2) Increasing hydropower to generate electricity
3) Maximum use of biogas and solar energy
4) Protecting and increasing the forests as they absorb Co2, the main cause of global warming.
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