At arch warmer site https://arstechnica.com/science/2020/04/a-puzzling-past-sea-level-rise-m… …. tells us sea levels have jumped surprisingly quickly and steeply in the past. It is funny how problems for the consumption of the general public are glossed over, or ignored – and then someone lets the cat out of the bag. I have often wondered how a now recognised smaller northern hemisphere ice sheet equates with a jump in sea level rise at the end of the Late Glacial Maximum (LGM). Apparently, it doesn't. The relevant paper is at https://doi.org/10.1038/s41561-020-0567-4 … where the argument revolves around precise dating. However, it begins by saying quite clearly that all the ice had melted (which is probably most of it) by 14,650 years ago – yet there was a large jump in sea levels at this point. Dates seem to change all the time but I am assuming this date marks the end of the Oldest Dryas event. It is less likely to be the Older Dyas event which was much shorter and less distinct. It appears, once again, that geochronology is causing a problem – and an insistence on relying on dates being reliable. The Oldest Dryas event is thought to have lasted 3000 years and follows directly on from the end of the LGM. In other words, the glaciation that reached its greatest extent was followed by a lengthy cold period. So, ice was melting and yet it was very cold. Probably not all the time but an average of temperature over those 3000 years. Now, one firstly has to wonder if the Oldest Dryas period really lasted as long as 3000 years and if it did what does that mean. We appear to have another C14 plateau which skews the dates. In spite of that the authors of the paper insist on sticking to the mainstream timeline and this creates the problem in which they seek to find an explanation. In a catastrophist scenario we might think that movements at the pole, not very large movements, can also cause sea levels to change as a result of ocean water finding a new equilibrium.
Assuming geochronology is correct, as the authors do, we still have a steeper rise in sea levels than current calculations allow. They then try and find out why that should be so. Eventually, they resort to a cave in China – and a stalagmite. They assume the subsequent speleotherm is reliably dated – when all speleotherms can offer is the big picture. They are nothing like tree rings in pinpointing a date – yet the title of the piece lays claim to the validity of 14,650 years ago. I think we still have a problem – but the cat is now out of the bag.