Q:  What is global warming and why is there such controversy surrounding this issue?

A: There are certainly myriad websites that go deeply into the global warming issue. I would suggest that take a look at those to delve even deeper into the topic.  The following web page at NCDC is a good place to start.

 http://lwf.ncdc.noaa.gov/oa/climate/globalwarming.html
 

--Michael Bell