Answer:
Scientists are aware that global warming is occurring (this has been measured), and is largely a result of human activity (the burning of fossil fuel). A lot of people have been convinced by large, well financed propaganda campaigns disseminating false or erroneous information that global warming has nothing to do with human activity, instead blaming things as prosaic as sunspots, solar flares, cosmic rays, methane, volcanoes, microsites (bad measurements), soot, ozone, and CFCs. Many of these same folks who claim warming is not caused by humans turn around and insist it isn't happening at all--that the warming stopped in 1998, or 2007, or 2010, and that Jupiter and Pluto are warming (meaning the sun must be causing it). Jupiter and Pluto are NOT warming, and the slight (unexpected) cooling of the sun over the past 40 years is not substantial enough to have had any measurable impact on any planetary climate.
Another view:
There are some scientists who dispute global warming, and a tiny handful of earlier proponents of it have backtracked and now deny it. The environmental movement has spent billions trying to destroy industry, and this is where the true propaganda lies.