Models. Prediction with no long term history of being correct. It's a doomsday cult. I would recommend going back to watch Al Gore's An Inconvenient Truth and see how many of the catastrophic predictions have come true.
https://nypost.com/2020/01/10/the-telling-tale-of-glacier-na...
The general trend is clear however and has been for decades.
Look into Bjorn Lomborg. I have no idea how accurate his stuff is, but he is the only one that actually seems to take a pragmatic approach to the problem and looks at the bigger picture
The trend is clear, the world is warming, we know the mechanism, we know the cause and we can calculate at least some of the results and we know they’re bad.
People saying “oh but things are always changing, there used to be an ice age” and things like that, completely ignore the pace of change.
You don’t need to panic but please don’t bury your head in the sand.