Fourth Assessment Report (AR4) was designed by IPCC (Intergovernmental Panel on Climate Change) to provide detailed analysis of global warming. It was written by 2500 experts and scientists. They have analyzed records from last 21 years incessantly. Here is the summary provided through AR4 report.
Global warming is unavoidable and is going to lead increase of air and ocean temperature and rise in sea level due to melting of icecaps. Rise in temperature in twentieth century is occurred only due of increase of anthropogenic GHG (Green House Gases) concentration. (In twentieth century global temperature is raised by 0.74 C and sea level is increased by 17 cm.)
Possible dangers of global warming are predicted as given here.
1. Disappearance of sea ice in later part of century.
2. Increase in frequency of hot streams, waves and heavy precipitation.
3. Increase in tropical cyclone intensity.
4. Decrease in natural water resources.
5. Ice sheets melting may result in sea level rise of 7 meters.
6. Population growth is going to stress over water resources.
7. Unpredictable atmospheric changes over the earth. Heavy rainfall would occur where it was not expected. In 2020, Africans are predicted to face sever water problems and farming may not get water.
8. Increase in sea water acidity: Due to anthropogenic atmospheric carbon, pH of water would decrease by 0.1 units. This is going to turn danger of marine plants and animals.
(This information collected through speech by R.K. Pachauri in Dec,2009 at Copenhagen, Denmark.)