There are generally three types of climate deniers:
Group 1) "climate change is not happening."
Group 2) "Ok, climate change is happening, but it's not anthropogenic."
Group 3) "climate change is happening, and Ok, is anthropogenic, but...the effects will be minimal , and certainly not worth changing our way of life."
--Due to the overwhelming amount of evidence from multiple independent fields of study, Group 1 has thankfully shrunk and most in Group 1 have migrated to Group 2. If someone is still Group 1 at this point, there's nothing you can do for them. It's like chemtrailers or flat-earthers. Evidence is irrelevant to them.
--Group 2's popular mantra, echoed by BrickHistory, is (to paraphrase) "the earth goes through cycles. Yes it's currently warming, but it has warmed in the past. We've had ice ages. We've even had periods in earth's history that are warmer than today. Therefore, we can conclude that humans play no (or negligible) part in it." This is the premier example of Dunning-Kreuger. It's a cringeworthy reminder that most people with a strong denial of climate change have literally never bothered to do any research into it at all. How do I know? Because any scientific book, journal, debate, lecture, etc. on the subject will immediately frame the problem in terms of rate of change. No credible scientist disputes that the earth has experienced large variations in climate. The difference now is the rate. It's faster. That's the core assertion. Change that used to take 10's or 100's of thousands of years is now occurring over centuries or decades.
Let's say you mow your lawn once every other week. The grass grows, you cut it. Cyclical. What sort of questions would you raise if you found yourself having to mow the grass every day. Or every hour. That's the difference. Not simply that the grass grows and you have to cut it, but that the rate is freakishly fast, and accelerating. So what would you do? You'd try to figure out why. ....did I use a different fertilizer? More water? Did I plant a new type of grass? Is there something in/under the soil? ....You get the point. You would try to isolate the independent variable. When it comes to climate change, there are indeed many natural factors that affect it (solar irradiance, axial tilt, etc.). But those have always existed. And they're measurable. Again, with just a little research you will find that science can easily isolate the variables. Those variables do have an effect, but they do not account for the massive increase in the current rate of climate change.
Group 2ers parroting the "Earth goes through natural cycles" are like someone having a really strong opinion on how the KC--NE game will go tomorrow. But as the conversation continues, it becomes clear they've never even heard of Patrick Mahomes or Bill Belichick. They saw a meme, or overhead something they thought sounded clever on TV and want to present it as their own. But they don't actually know anything about the two teams. Or maybe even about football. ....So you cringe, possibly roll your eyes, and go find someone else to talk to.
--Group 3ers concede to the overwhelming evidence, but try to minimalize it. Their group is, in my experience, characterized by pessimism, apathy, and defeat. As you've heard here, Group 3ers will say 'China and India are larger carbon emitters.' Or that wind/solar/renewables are expensive and consume energy to build, thus negating the effort. The mantra is essentially, "it's too difficult.....so fvck it." Not the America I know. We are the global leader, the superpower. We have global influence. Other countries do what we do. At least for now. If we would simply lead, others would follow. Likewise, innovation is tough. Maybe solar and wind aren't the end-all, be-all. Or maybe not in their current form. We have to experiment. Risk failure. We have to try. There are dozens of proposed lines of effort out there....we don't need all of them to work. But none will work if we just give up. It's a complex problem, like say, landing a man on the moon and returning him safely to earth. We could embrace the challenge and see similar results as the space race -- leaps in technological advances, achievement of a common goal, etc. Or we can say 'fvck it, it's too tough for us. Let's let China or the EU figure it out.'
For those of you in Group 1, 2, and 3, I will close with this: Climate change is happening and is anthropogenic. There is no question of that basic premise. Donald Trump and Joe Biden and AOC and Nancy and Mitch will all come and go. Even Al Gore will be gone one day. But climate change will be with us for the rest of all our lives. And our children's. It's not going away, and I encourage you each year, or each decade to pause and ask: "Hmmm....is that pesky climate change thing over yet? Did the scientists, who dedicate their lives to understanding this, collecting data and evidence in dozens of fields of study, all over the globe finally realize they were wrong this whole time and that the earth 'just goes through cycles?' Did they finally give up and admit this was a leftist conspiracy and a hoax to drive a carbon tax?" The answer will be No. We can discuss, like ViperMan suggests, the validity of specific policies and proposals and the way forward -- that's where the debate needs to be. But again, for the record, 100%, you will not see anthropogenic climate change just fade into a non-issue or revealed as some sort of elaborate hoax. In your whole life. Regardless of the petty noise and friction and squabbling on the internet, in the media, or even in the halls of congress.