The list will grow...
Is there Consensus on Climate Change?
Yes there is unusually high consensus among climate scientists that climate change is happening and is caused by humans. The number is 97%+. In contrast only 91% of people think smoking causes lung cancer.
Why is there so much skepticism on climate change?
That's a tough question to answer given the 97%+ consensus but some work has been done by George Mason and Yale to name a couple. A lot comes down to tribalism. People tend to believe what their group believes, especially if the issue is not of utmost importance to them. Other causes of caution are lack of visible evidence in one's local area, need to distance oneself from overwhelming problems that one does not have control over or big money lobbies spreading misinformation. The list is long. Read more here.
How do I best engage someone who does not believe climate change is real or human caused?
There is no correct way. Everyone is different. So first you must understand why they are skeptical. Do they want limited government? Perhaps then they are afraid that admitting the climate change reality will lead to more government control. In other words, the possible solutions are more scary than the problem. Perhaps they are someone who believes humans can't possibly impact the climate since God is in control. There are various examples. But the bottom line is that you must meet them where they are!