Living with Uncertainty

The precise thresholds for most tipping points remain uncertain. Scientists know approximately where the boundaries lie, but they cannot specify exact temperatures with confidence. This uncertainty does not make tipping points less dangerous. It makes them more dangerous, because we might cross them without realizing it until the irreversible process is well underway.

Some scientists argue we may have already crossed the threshold for West Antarctic ice sheet collapse and for Greenland ice loss at current warming levels. If so, significant sea level rise is now committed regardless of future emission cuts.