The larger scale models aren't necessarily built on the smaller models, they are independent and generally less specific. They are probably even inputs to the more specific models. So, like rising sea levels and increased temps (on average) is basically guaranteed, the _exact_ change for a particular place is more uncertain.
Neil deGrasse Tyson in his Cosmos show described it like a person walking a dog. We don't know where the dog will be exactly, but we can see the person with the leash is moving in one direction, and the dog isn't going to ever get too far from him (because of the leash).
But the uncertainty in the dog analogy is the length of the leash. If we don't know the length of the leash, we can know the general directionality but can't make very strong conclusions about where the dog will be, right? I don't know that this supports the idea that uncertainty will only be around the edges; I've heard NDT talk about the opposite: even a small shift in in the average causes relatively large changes in the probability of (previous) long-tail events.
A more accurate drill down on the analogy would be that we don't know the exact length of the dog' leash either, but we do know what the limits of it are. We know it's not a 1 km leash, but the "uncertainty around the edges" encompasses not knowing if it's 2 m or 0.5 m.
Part of the accuracy of the analogy is that just like when you see the human from a long distance, you don't know exactly how long the leash is, but you do have a solid expectation of the rough upper bound for the dog's distance from the human even still.
With climate change you're talking about having seen the human walk half way down a block already. You can see they're continuing to walk the same direction, and everyone agrees they'll continue walking to the end of the block if nothing changes. Do we know exactly where the dog is during that whole walk? No, but we do know it will cross a line two thirds of the way down the block sometime before the human reaches the end of the block. And the likelihood of the dog crossing is greater and greater the further along the block the human is.
>but we do know it will cross a line two thirds of the way down the block sometime before the human reaches the end of the block.
I'm trying to be careful here because I don't want to come across as if I'm against investing efforts to mitigate climate change. But in the real world, it ultimately comes down to trade-offs. So I agree with the premise that eventually, if unabated, climate change will likely cause "bad" outcomes. Apropos to this thread, though, is the definition of "bad". And from what other commenters have shared, there is large uncertainty of both the "low" and "high" temperature change models out to about 2070 or so.
In other words, even if the circumstances meet the definition for a "high" temperature change it may result in the same outcome as if it were a "low" temperature change, but the mitigation efforts would likely be drastically different. In a world where the solution is trade-offs, mitigating for one scenario over the other comes with real consequences. The point I'm trying to get at here is that I think uncertainty has to be a larger part of the conversation when we're talking about competing risks, especially when that uncertainty is relatively high. While uncertainty is a central part of a scientific discussion, my hesitancy about even bringing this up is that I also recognize that highlighting uncertainty is also a tactic of bad-faith actors to undermine any reasonable conclusions.
Neil deGrasse Tyson in his Cosmos show described it like a person walking a dog. We don't know where the dog will be exactly, but we can see the person with the leash is moving in one direction, and the dog isn't going to ever get too far from him (because of the leash).