Wednesday, April 22, 2015
That Australian life - NSW storms with a dash of sea level history
This photo by Dallas Kilponen from the Sydney Morning Herald shows the waves hitting Wylies Baths (the baths themselves are under water) at the Sydney beach side suburb of Coogee.
The waves were quite something. On Tuesday, a monster wave with a maximum height of 14.9 metres was recorded at 3pm, eclipsing the previous high of 14.1 metres set during the 2007 east coast low that washed the Pasha Bulker commodity carrier ashore near Newcastle. I wrote a post on that east coast low (New England's Wild Weather), in part because it came after drought, in part because of its scale. If you click on the link, you will see a photo of the Pasha Bulker that gives you an idea of then wave scale.
In an earlier post (New England prehistory: creating synthesis in the face of destruction), I mentioned that my present historical research was focused on prehistoric New England. My best guess is that the Aborigines came to Northern NSW between 30,000 and 40,000 years ago, although the earliest radio carbon dates are c20,000 years ago. As part of the process, I have been trying to map dates against changing sea levels and climatic variations.
Let me give you a number here just to attract your attention. Over the last 100,000 years, sea levels have fluctuated from perhaps 120 metres below current levels to a metre above.I was thinking of this as I listened to the storm reports. This variation was most pronounced over the last twenty thousand years.
I don't want to get into the now almost theological debate on human induced climate change. However, I am interested in sea level trends. During the Holocene Warm Maximum period that began c9,000 years ago, average temperatures were around half a degree hotter than they are now, the sea was a metre higher than now. That warm maximum period was replaced by a colder phase that saw sea levels fall.
We may or may not have entered a warmer phase now. Its interesting, however, to realise the scale of natural changes regardless of cause.
kvd, I mentioned John Mulvaney in a comment. This video may be of interest. Professor Mulvaney was mentor to Isabel McBryde who I think of as my personal mentor or role model in some of these areas: