I think if you read the full IPCC report you will see they are far from dramatic. Often news articles on the reports include calls to action (which I am all for given the path we are on). I believe the IPCC may also issue a statement about the report as a whole on release. However, if you read subsections of the full report you will see each domain specialist assign low medium or high confidence to each potential climate outcome. They also include useful descriptions of the physical mechanisms behind many climate phenomenon

There is a great podcast that goes through the whole IPCC report in something like 70 episodes. It's in german though, so not quiet sure how helpfull it could be for you, but maybee there is something similar in english. The podcast mentioned is "https://dasklima.podigee.io/" . Discussion about IPCC goes on until episode 77, after that they discuss some broader topics.

I happen to speak German, thank you!

When you frame it that way, your question is "how can $NONEXPERTS confirm $EXPERTS"

First and foremost: read.

Second: don't demand certitude and table the idea that there's a universal judgement. Think: am I asking for an up/down vote on a conversation, or on an assertion?

Uncertainty can't always be driven down to 0. People usually expect this from other fields and yet understand when it is silly in their own field. (imagine: climate scientist forum noting cosmic rays, asking how any system can possibly be secure given memory safety causes security issues, and cosmic rays can flip memory bits, then hand-wringing about how they can even figure out what software research to trust)

This thread is itself a good example: OP has no issue with the research, or type of research, or anything, just is concerned how laypeople might believe it is certain and confirmed because it is in Nature. The paper itself makes no such claim, as the OP goes to great lengths to explain (c.f. it is statistical model)

Dramatic? The IPCC is perhaps the driest bit of prose there is.