Runaway greenhouse effects are global, not local. It would be caused by a self-reinforcing feedback where the warming releases more CO2, but that would quickly spread over the entire planet.

There are lots of possible causes for the extra warming in the Arctic in particular, but the high-level view is that ice is more reflective than water, so the increased area of water surface absorbs more heat. There's going to be a lot more to it than that, from the way water and air flow within and around nearby regions, but it was expected that the Arctic would warm faster than the rest of the planet.

Runaway greenhouse effect on Earth is impossible for a billion years or more for a variety of reasons. You're looking for doomsday cult nonsense rather than minor/major climate changes that are more nuanced and more probable.

You're right in that our atmosphere will not soon "prevent the planet from cooling and from having liquid water on its surface." In other words, yeah, we aren't going to literally boil the oceans. We shouldn't throw around the term "runaway greenhouse" in serious discussions of anthropogenic global warming.

However, reality is somewhere between "doomsday cult nonsense" and the flippant, dismissive tone of your comment that characterizes the worsening climate crisis about which our species is not doing enough as "minor/major climate changes." That's definitely understating the costs and disruptions that human civilization is facing on its current course.

I wonder if OP was referring to any of the more immediately concerning positive feedback loops: https://en.wikipedia.org/wiki/Climate_change_feedback#Positi...

>I wonder if OP was referring to any of the more immediately concerning positive feedback loops

Yeah, that's why I prefaced it with it being a dumb question. :)

If the feed backs are accelerating global warming, it wouldn't be too distant a notion from the premise of runaway greenhouse gases.

I'll have to brush-up on my nomenclature to not ask such bone-headed questions in the future. :(