Science communication and trying to appropriately communicate risk has a lot of issues, yeah. I don't really blame them because there's been more than two decad

Science communication and trying to appropriately communicate risk has a lot of issues, yeah. I don't really blame them because there's been more than two decades of very obvious failure to get sufficient numbers of people sufficiently politically engaged to change enough to avoid catastrophic outcomes. In general, if you're a relatively high information person, you should probably be looking up the actual reports themselves by organisations like the IPCC. As to your 1/2/3 scenarios, 1 is basically impossible at this point unless every major country starts extremely rapid decarbonisation, like zero carbon within 15 years sort of thing. We think we are on track for option 2, and with predictable mitigations (countries successfully pull off all pledged reductions) it's still pretty much 2, just potentially less severe. By "less severe", I mean we can try to prevent at least some of that sea level rise which means there will be some cities that become coastal but don't get catastrophically flooded. But like, Miami for example, that city won't exist by the end of the century without a hypothetical and unproven seawall (people always say seawalls, sure it's a decent idea, but we don't know if it's even feasible for us to build them to the necessary standards. It's like asking every coastal city to build something more complex and safety critical than Hoover Dam). An important thing to think about is that the difference between 1 and 2 is class based. When I said 1 was impossible, I meant that it was impossible for like "most people", because we're on track for billions of people to become refugees because of climate change, likely leading to wars and significant political issues. But obviously if you're wealthy enough, you are basically insulated from those outcomes because you can just keep moving away from the coast (even if millions of other people are trying to move there at the same time) and the only real impact on you is the broader economic impacts on the country you live in, and even those are muted. So for the wealthy, it's always really been a question of "Is it going to be 1 or 3?", which is a big part of the reason why it has been so immensely hard to see significant political change to prevent anthropogenic climate change. We don't really understand the science of 3 well enough to understand what the tipping points would be to start a runaway greenhouse effect, so no one knows for certain. We need more science on it. I think a very reasonable guess is that it won't happen until our greenhouse gas heat retention is at least as high as it was during the various times in Earth's history when the polar ice caps didn't exist, which gives us significant runway to work with. Beyond that, we just don't know.