Would someone please tell me the truth?

Apparently, there is a group of scientists who are contesting the United Nations claim that global warming is leading to rising temperatures.  We’ve heard this kind of thing before.  Awhile ago, eggs were considered healthy, then a report came out saying eggs were bad.  Then, a few years later, another report said that eggs were good again.  Now, the same thing seems to be happening with this whole global warming issue.  The problem, we can’t afford to wait 20 years to find out if pollution is causing global warming or not.  It makes sense to me to act like it’s the truth and enact pollution reduction measures just to be on the safe side.