GLOBAL WARMING & CLIMATE CHANGE

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 20^th 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 20^th 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.

Due to rise if ocean water temperature in Indian Ocean, during 1997-98 catastrophic coral bleaching was observed caused death of almost 7-% of the corals near Andaman and Nicobar and Lakshadweep islands. An analysis suggests that sea temperature has risen by 0.6% C during later half of 20^th century.

4.       Other Evidences-

·         Thawing of permafrost areas.

·         Greening of Taiga and Tundra Forests

·         Spreading of tropical diseases to towards temperate and polar regions.

·         Shifting of seasonal weather phenomena and changes in precipitation patterns.

·         Increased frequency of extreme weather events.