Check your link again. It says we are living in a time with relatively high sea levels, the opposite of what you claim.
Read the text again carefully! From the caption under the figure I linked: "Note that over most of geologic history, long-term average sea level has been significantly higher than today.".
In case that was not clear if over much of geological history sea level has been higher than today this means that we are living in a time of relatively LOW sea level. If you don't believe that then just look at the data in the plot!