Greenland is bad, the melting was so bad NASA scientists thought they’d made a mistake:
However the tipping point we should really be worried about is a sudden release – or pulse – of methane into the atmosphere, triggering a runaway greenhouse effect.
In short, rising temperatures help unlock the billions of tonnes of carbon locked up in the under the Siberian permafrost.
The permafrost is a lid, under which is billions of tonnes of methane. Methane is a far more potent GHG than carbon (it traps more heat). More methane, more heat. More heat, more warming. More warming, the greater the risk of other tipping points.
How does such an event rate on the scale of probability?
Well it depends.
Do we really want to find out?