Point Of No Return Meaning

(idiomatic) The point in any journey, process, or sequence of events when it is no longer possible to reverse course or stop the process.

Example: 2005, Steve Connor, "Global warming 'past the point of no return'," The Independent, 16 Sep.:
  A record loss of sea ice in the Arctic this summer has convinced scientists that the northern hemisphere may have crossed a critical threshold beyond which the climate may never recover.