How come climate articles always tell us that sea levels will rise by metres over the next 50 years but never tell us how much sea levels have risen over the previous 50 years?

https://www.quora.com/How-come-climate-articles-always-tell-us-that-sea-levels-will-rise-by-metres-over-the-next-50-years-but-never-tell-us-how-much-sea-levels-have-risen-over-the-previous-50-years