Various man-made factors have significantly contributed towards “Global Warming”.The ‘Green House Effect’ is one of the most significant factors.The major green house gases are water vapours,which causes about 36-70 % of all the green house effect,carbon dioxide which causes 3-7 %.Clouds also effect the radiation balance through cloud forcing similar to greenhouse gases.

Human activity,since the ‘Industrial Revolution’ has increased the among of green house gases in the atmosphere ,leading to increased temperature forcing from Carbon dioxide,Methane,tropospheric ozone,CFCs and nitrous oxide.The concentration of Carbon dioxide and Methane have increased by 36% and 148% respectively since 1750. Less direct geological evidence indicates that carbon dioxide values higher than this were last seen about million years ago.

 

 

Fossil fuel burning has produced about 3 quarter of the increase in carbon dioxide from human activity over the past 20 years.The rest of this increase is caused mostly by changes in land-use,particularly ‘deforestation’ alongwith burning fossil fuel. Over the last decades of the 20th century,gross domestic products,per capita and population growth were the main drivers of increase in green house gas emissions.

 

Carbon Dioxide emissions are continuing to rise due to burning of fossil fuel and land use change.Emissions scenario ,estimates of changes in future emission levels of green house gases,have been projected that depend upon uncertain economic,sociological,technological and natural developments.Fossil fuels are abundant and will not limit carbon emissions in the 21st century.

 

The popular media and the public often confuse global warming with the ozone hole.i.e. the destruction of stratospheric zone bu chloroflouro carbons.Although there are a few areas of linkage the relationship between the two is not strong.Reduced stratospheric ozone has had a slight cooling influence on surface temperatures,while increased tropospheric ozone has had a somewhat larger warming effect.

 

Various impacts witnessed are being evident owing to the “Global Warming” .It has been detected in a number of systems.Rising sea levels are consistent with warming.Most of the increase in global temperature since the mid 20th century is,with high probability,attributable to human-induced changes in green house gas concentrations.Even with current policies to reduce emissions,global emissions are still expected to continue to grow over the coming decades.

 

Changes in regional climate are expected to induce greater warming over land,with most warming at high northern latitudes,and least warming over the southern ocean and parts of the North Atlantic Ocean.Snow covered areas and sea ice sheets are expected to decrease,with the Arctic expected to be largely ice-free in September 2037.The frequency of hot extremes,heat waves,and heavy precipitation will very likely increase.The frequent occurance of the natural catastrophes especially related to flood outbursts are said to be one of the impacts of the ‘global warming’.The eco and social systems show clear evidences of the global warming too.