A lot of terrible responses here, but here's my terrible take: 1. First are they wanting to discuss anything with you, or are you passively watching them on so

A lot of terrible responses here, but here's my terrible take: 1. First are they wanting to discuss anything with you, or are you passively watching them on social media and now wanting to engage? The latter is different and falls more under science communication than an exercise in epistemology. 2. Practice the principle of charity and giving benefit of the doubt. You aren't convincing them, but trying to understand each other's opinions and claims so you can both converge on a better understanding of the world. 3. Come to some agreement that you are both not experts on the topic, so much of both of your opinions are on your own understanding of so-called-expert's claims (both for and against man-made climate change). Also important here is experts should have evidence readily available so that claims can be reviewed by other experts. 4. Try and come to an agreement that you will both "write" something like a page that each can read and respond to .What their top 3-5 arguments are supporting their opinion. What is 1-2 pieces of evidence that would convince them the other position is more correct. Limit it to like 2-3 replies back and forth. Try and agree that no additional arguments would be mentioned so that you can both come to a shared understanding of the 3-5 claims. Direct citations and links are helpful so that there is enough specificity to review. 5. Most likely you'll end up agreeing to disagree. It is a complicated topic, but hopefully both of you will continue due diligence in understanding the science. IMO having structure and time between exchanges helps focus the discussion. Unless you are already neck deep in the topic, anything you say impromptu will not be convincing because you won't have a sufficient background to explain the evidence and any counter-arguments to the evidence. I highly recommend the book "The Skeptics' Guide to the Universe: How to Know What's Really Real in a World Increasingly Full of Fake" which is close to a reference manual for how to think critically. The podcast they have is great. Good luck!