Global warming refers to gradual rise in
atmospheric and ground surface air temperatures and conseques changes in global
radiation balance, caused mainly by anthropogenic processes leading to climatic
changes at different levels. Global warming is a result of rise in proportion
of atmospheric green house gases (GHG) than their normal level. The rise of GHG
levels has been attributed to the process of industrialization, urbanization
and pollution caused by vehicular, industrial, domestic and agricultural
emissions. The main component gases of GHG emissions are – carbon dioxide,
methane, chlorofluorocarbons, nitrous oxide and ozone. The processes of global
warming have led to the effects of climate change, the evidences of which have
been scientifically corroborated by international panel on Climate Change
(IPCC), formed under United Nations Framework Convention on Climate Change
(UNFCC) and constituted by United Nations Environment Programme (UNEP) and
World Meteorological Organization (WMO).
Evidences
of Global warming:
1.
Increase in air temperatures: It has
been estimated that the overall increase in the air temperature in 20th
century has been about 0.5 to 0.7º C. The 1990s saw seven out of ten warmest
years of last century. The global circulation models have shown rise of 0.4 to
0.8º C in the 20th century. The increase in frequency of EI Nino
events, hurricanes and cyclones between 1970s to 2012 also denotes climatic
changes due to warming of earth’s surface and its atmosphere. IPCC report has
shown that concentration of atmospheric CO2 has increased.
2.
Melting of Mountain and Continental Glaciers: Many reports have suggested that Himalayan Glaciers have receded. Similarly there have
been reports of retreat of glaciers in Alps of New Zealand. Mt. Kenya has lost
its most extensive glaciers in the past century. The glaciers of Greenland too
have been detaching and receding at fast pace.
3.
Warming
of Ocean Water and melting of ice Sheets and ice Bergs in Antarctic and Arctic
Sea.
