How confident are scientists that global climate change is human-driven?

This is a very debatable topic, because it is hard to be sure how much climate change is human driven. There have been past climate changes occur due to natural gas build up prior to our pollution of the air. Scientists do feel we have contributed and some say we are the cause, but others believe it is a natural cycle that the earth goes through based on past records and samples from the ground and such. Global Climate Change could undeniably be because of human-made pollution; however, we do not know everything, and we cannot be sure of the initial cause this go around.  There are die hard scientists that fall both ways, and there are those that say it is made up by government officials. If you really look into global warming it is quite intriquing.