Waves

It is acknowledged that we have almost no information about the occurrence of storms in ancient times (say before the 20th c.). Past climate changes have been identified, inducing cooler and warmer periods. During one of the cold periods, a “moderate increase in storminess in the high-latitude North Atlantic region” is mentioned (Giosan, 2018, O’Brien, 1995). More recently, we may have an indication that warming of the Arctic area is reducing the frequency and the intensity of storms (Routson, 2019). Similarly, recent mathematical modelling shows that 21st c. global warming may lead to “a decrease in average wave height but increases in the maximum waves” (Bricheno, 2018).

The climate of the Roman period from 200 BC to 100 AD is considered fairly close to ours, with a cooler period before that and after that (see Ancient Climate/Temperature, Beresford, 2013, p 60). Hence, and in the absence of further proof, we usually suppose that the ancient wave climate is similar to the present one.

References

BERESFORD, J., 2013, “The ancient sailing season”, ed. Brill, (364 p).

BRICHENO, L., & WOLF, J. 2018, “Future wave conditions of Europe, in response to high-end climate change scenarios”, Journal of Geophysical Research, Oceans, 123, (p 8762–8791),
https://doi.org/10.1029/2018JC013866.

GIOSAN, L., 2018, “Neoglacial Climate Anomalies and the Harappan Metamorphosis”, Climate of the Past,
https://doi.org/10.5194/cp-2018-37.

O’BRIEN, S., et al., 1995, “Complexity of Holocene Climate as Reconstructed from a Greenland Ice Core”, Science, New Series, Vol. 270, Issue 5244, (p 1962-1964).

ROUTSON, C., et al., 2019, “Mid-latitude net precipitation decreased with Arctic warming during the Holocene”, Nature, Volume 568, Issue 7750, (19 p).
Acc. to Routson (2019) “The Arctic has warmed more than low latitudes naturally in the past […] resulting in smaller temperature differences between the Equator and the pole, the jet stream gets weaker and less precipitation falls in the mid-latitudes” because of “reduced baroclinic potential energy that fuels storm systems, reducing mid-latitude cyclone frequency and intensity”.
See also: Northern Arizona University News.