Early warning signals are features or properties to a system that change in a regular fashion as the system approaches some critical transition, with it being possible to use these regularities to predict in advance when a system is likely to turn critical. Ongoing research in different scientific fields is now suggesting the possible existence of generic early­ warning signals that may indicate for a wide class of systems if a critical threshold is approaching. Thus, the actual distance to such transitions, or how much more some parameter needs to change for the system to experience a significant qualitative change in its dynamics, remains an important empirical challenge; so does predicting the state of the system after this point is breached. One of the most promising theories in this areas is called critical slowing down.