Every pause starts with one small step. The step can be backwards or sideways.
But this can be due to a multitude of factors.
The pause is confirmed when a second reading is also sideways or backward.
Mind you it is a very temporary pause and of very little import.
Further readings can be up or down and still be a pause as long as the average of the readings from the first step remain at or below the last reading that was he start of the pause.
Now comes the interesting part. Defining a pause as the length of time from the initial start point would give a decline instead of a pause if the readings over time continue downwards
A pause is actually a leveling of the readings, which dates from the last reading backwards.
Hence after say 20 readings downwards one has to take extra readings from the upwards part of the graph to balance out or level the new downwards section. The way to do this is to take the line across from the last reading to the new first reading, then evaluate the area above the line and take the average level here as the length of the pause.
Obviously the start of the pause is not where the line goes across from the last reading but a little higher,
The point is though that the pause extends backwards as well as forwards as long as the last measurement puts the average below the initial measurement when the pause started.
When the average starts dropping significantly the pause extends out dramatically.
When does a pause become a reversal or fall?
1929 is a good answer. A fall or reversal starts with a similar change to a pause only it is never a sideways step always down.
The only answer can be in retrospect although a good sign is a preternaturally large fall. The global climate changes constantly and a big fall is only likely through a catastrophic event which mankind cannot ward against.