2. How world temperatures have been changing in the past century?

3.  Global surface temperatures have risen by almost a degree in the last century. Sea levels have risen, while snow and ice cover has dropped significantly. Coral reefs are being destroyed and weather patterns are becoming wilder and less predictable. And the major cause of this climatic mayhem is now clear. It is the work of humans, who are burning ever increasing amounts of fossil fuel and have raised carbon dioxide levels in the atmosphere by 40% in the past 250 years.

4. How this change has affected glaciers??

5.  Global sea level rising  When temperatures rise and ice melts, more water flows to the seas from glaciers and ice caps, and ocean water warms and expands in volume. This combination of effects has played the major role in raising average global sea level between four and eight inches (10 and 20 centimeters) in the past hundred years, according to the Intergovernmental Panel on Climate Change (IPCC).  http://environment.nationalgeographic.com/enviro nment/global-warming/big-thaw/#page=2