Scientists think there's a decent chance that, if global temps rise 2 degrees above pre-industrial levels, it could trigger a cascade of tipping points that further accelerate warming, up to 5 or 6 degrees.
AKA: "A cluster of abrupt shifts occur in ESMs [Earth system models] at 1.5 to 2ºC."

Climate change is not linear: why we need to update the Paris Agreement
For a few years, scientists have been warning that even if we hit Paris targets, we could cross several tipping points that could trigger a cascade into total climate breakdown.
‘A clust...