"Another element to consider is whether this increase is driven by a few but extreme events. However, when we look at the 25% and 75% quartiles – the former shows the change across 25% of the weeks with the least volatility, and the latter shows the change for 25% of the weeks with the highest volatility – the trend is increasing for both," said Alan Murphy, CEO, Sea-Intelligence.

"It means that volatility is increasing not only in the weeks with high changes, but also in the more stable and 'calm' weeks," he added, noting that this shows an increased volatility in the overall supply/demand balance on Asia-NAWC.

"To the degree that spot rates are driven by the actual weekly supply/demand balance, this capacity volatility means that the underlying driver for spot rate formation on Asia-NAWC has become progressively more unstable over the past 13 years – creating a much more volatile and unpredictable spot rate in itself," Murphy said.

To get a better understanding of the severity, Sea-Intelligence said it took an absolute value of the week-on-week change, so that any change is recorded as a positive value, irrespective of whether the change is positive or negative. Furthermore, to look deeper into whether there is any systemic change, it calculated capacity volatility as a 52-week moving average.