Since you haven't responded, let me guess: You're trying to imply that because there was a very large sea level rise between 20k and 8k years ago, that somehow makes the unprecedented in the common era rise over the last century unimportant?
If so then you are either being purposely misleading or you don't understand that the very large sea level rise between 20k and 8k years ago was due to the end of the last ice age. See where is says "last glacial maximum"? That is the peak glaciation of the last ice age. As the ice age ended and all that ice melted sea levels rose quite a bit - duh. But why stop there - why not plot the previous interglacial periods where sea levels drop and rose again?
Where did you get your 20" /century rise number - from averaging in the post ice age melt rise?
You wouldn't be purposely trying to misrepresent the history of sea level change would you? I hope not.
This is an engineering forum - that kind of thing will not fly.
The history of sea level rise immediately following the last ice age is irrelevant to the question of how the rate of sea level change over the last century relates to the rate of sea level change over the previous 27 centuries. If you read the study I linked to you'll see that the whole point is that the rate of change has acclerated dramatically and the only explanation is the global warming that has occured during that period.
Below you'll find a few plots from that
that study:
The first one shows global sea-level change and associated global temperature anomaly.
The second one shows counterfactual hindcasts of global mean sea-level rise in the absence of AGW.
As the authors conclude:
Counterfactual hindcasts with this model indicate that it is extremely likely (P=0.95P=0.95) that less than about half of the observed 20th century GSL rise would have occurred in the absence of global warming, and that it is very likely (P=0.90P=0.90) that, without global warming, 20th century GSL rise would have been between ?3 cm and +7 cm, rather than the observed 14 cm. Forward projections indicate a very likely 21st century GSL rise of 52–131 cm under RCP 8.5 and 24–61 cm under RCP 2.6, values that provide greater consistency with process model-based projections preferred by AR5 than previous semiempirical projections.