A.
The scientific tools for detecting thresholds are very basic, which means that it is impossible to accurately detect tipping points
B.
Scientific uncertainty. Some parts of the earth system appear to be much more resilient than previously thought, while other parts of the earth system are providing indications that they are in fact less resilient and may even have crossed a tipping point
C.
All identified thresholds leading to tipping points in the earth system have been crossed and the challenge is to address the implications