In science, the facts are not opinions. They are the experimental results.
Except what you're referring to is not even remotely equivalent to "experimental results." We do not have the capability to "experiment" on a global climate under controlled, observable, repeatable conditions. Instead we build computer models based on how we think the climate actually works, all of which are only as accurate as our understanding of climate -- and that understanding is woefully inadequate. Thus the models are gross simplifications of the actual climate, some of which start with the presupposition that climate change is due to man-made CO2 and work backwards from there to make the data and models fit. The results have been models that accurately predict the past but inaccurately represent the present, or if they accurately represent the present they do not match the past. Over time the models get "massaged" to make things fit, always with the assumption it all must be man-made CO2 at the core of it.
I have a built-in distrust for such procedures because there are no effective ways to challenge or prove them experimentally. Additionally, the core climate community has become largely homogeneous by self-selection, where dissenting voices are banished in order to achieve the desired consensus. Grant money is doled out or withheld depending upon whether the findings will support the agenda of the giver. When big business does this it's called astroturfing, being a shill, etc. and is not to be trusted. When government and "big science" does it it's called "consensus" and questioning it is blasphemy of the highest order. Publishing is similarly segregated with any dissenting voice being treated as a pariah.
Do I believe the climate is changing? Absolutely. It was changing before humans arrived, being both significantly warmer and colder than it is today. It is changing while we're here. It will continue to change despite our wishes because we lack the technology to effectively stop it on short timescales. It's the height of anthropocentric arrogance to think the planet's climate is going to sit still for us just because we happened to develop opposable thumbs at this point in Earth's history.
Do I believe human activity is contributing to climate change? At some level it must be as any activity by definition has some kind of impact. The question then becomes how much are we affecting it and, if we reverse course, will the anticipated benefits outweigh the social and economic upheaval such a reversal would cause? Keep in mind sometimes it is better to adapt to change rather than fight it. Some areas currently too cold for agriculture would become more suited to it while other currently-arable areas would become too hot or dry. Certainly it is disruptive -- any change is -- but is the net result positive, negative, or neutral? Nobody has answered that question. To my knowledge the question isn't even being studied on any reasonable scale. Everything's being thrown into the we-have-to-stop-the-climate-from-changing bandwagon, a fool's errand if there ever was one because climate will merely laugh at our puny efforts.
There used to be a time when scientists welcomed questions and opposing ideas and were eager to put their hypotheses to the test. Today...not so much. "There's too much at stake" they say, to entertain skeptics or those that question. Instead they're labeled as "deniers" and treated like knuckle-dragging inbred simpletons at best or traitors to humanity and murderers at worst. The "we have to do something!" crowd is the loudest, saying we can't wait to get firm data and must enact sweeping changes regardless of what it does to anyone. That the worst effects would be felt by prosperous Western nations while third-world and far East polluters would suffer less or not at all. As that fits the current "punish the West for all ills" popular mantra is more than a little suspect so I'm similarly not inclined to believe or support anyone pushing such "climate reform" that doesn't call for all who benefit equally to pay equally as well.