Different systems - from the brain to finance - send out similar warning signals before the onset of a major transition.
An example of a general warning signal before a transition is a slow recovery after disruption, called a 'critical slowing down'. Another warning signal preceding a critical transition is 'flickering'. Van Nes: 'Flickering is when disruptions cause a system to oscillate between two equally balanced situations, such as from 'cultivated' to 'desert' and vice versa, or from a clear to a murky state in a lake.' A third signal is when fluctuations in a system slow down but become bigger. It's as if today looks more and more like yesterday. The elements in a system will increasingly resemble one another. This principle is evident in the transformation of an area into a desert. Patches of vegetation look more and more alike just before the critical transition into desert landscape. Something similar happens in an epilepsy attack: the brain cells display notable synchronic activity just before the attack. When a financial system nears a tipping point, its elements - people - also become copycats. 'In an uncertain financial market situation, traders do what other traders do', explains Scheffer. 'When things start sliding, everyone follows and panic breaks out.'