[mongol]

> Also, there will be significant consequences for humans (which could be catastrophic and hard to predict if we don't limit warming to say 2C)

I have trouble visualizing what form the catastrophe would take. The worst I can imagine is global famine, is that what we are talking about here? Or rather local famine, acting as catalysts to civil unrest, wars etc?

Basically, I think the climate debate gets fuzzy here. Granted, just like you say, it gets hard to predict, but given that, what makes certain temperatures a threshold for disaster?

[Wojtkie]

If oceans get too hot, fisheries will collapse and wreck coastal communities. Sea level rise will make storm surges worse and make "once in a lifetime" events more common.

This instability will drive a migration of people inland, essentially as ecological refugees.

[valval]

Then what? Keep going.