BOLD CAPS IS GENERALLY REGARDED AS STANDING ON A TABLE AND SHOUTING OR THE RANTING OF A LUNATIC. It really should be used very sparingly
And now to my response. Here is the Wikipedia version of MSL
https://en.wikipedia.org/wiki/Sea_level. MSL conceptually makes sense but as usually the devil is in the details. Yes sea level varies over time and the vast majority of folks do not worry about the details but professionals like engineers land planners, architects and developers have to worry about the details. Generally one of the roles of government is that in situation where there is a need for a common standard that the government will take the lead. Such is the case for the precise definition of MSL. The USGS and a few other government agencies maintain a network of benchmarks around the country which are fixed points in usually publicly available locations. The average person has no need for access to these benchmarks so they don't notice them. Many federal post offices have them. For someone like me that hikes up mountains, there are frequently brass benchmarks on summits of mountains that have good view of the surrounding countryside. Many of these brass benchmarks have space for the elevation above MSL but most arent filled in. Its not that the surveyor who installed it was lazy, as much as MSL changes over time. To deal with this variation, there are agreed upon datums that are put in place where based on available data and exact elevation standard is established and all elevations should be referenced to that elevation. The link
https://www.ngs.noaa.gov/datums/vertical/ is good reference to the datums in place around the world.
I did a study several years ago for power plant system that was potentially impacted by actual sea level as the plant drew it cooling water from an ocean bay. I was chasing a fairly precise measurement over a long term and had to take into account change in MSL in the calculations. In coastal areas where sea level is very important various parties keep long term records of tidal variation listing high, low and mean tide tied to benchmark. I located a site near the plant and obtained the long term records from the sire for around 50 years and then came up with a long term change in the actual seal level at the plant intakes. It supported that there has been consistent trend in sea level rise so 0 MSL based on the 1928 datum is now effectively below the actual current sea level. The vast majority of the scientific community agree that Anthropogenic global warming is impacting sea level due to warmer average climate and multiple indicators support this. If you do not want to use the widely accepted Anthropogenic reason for sea level rise and go with long term natural variations in climate, the short term variation over 100 plus years from multiple sources is the actual sea level is rising. In New England tidal action is more extreme and its usually the high tides that coincide with onshore tidal surge that cause the problems. The combination of a higher actual MSL and a more energetic climate (a warmer atmosphere means bigger storms), leads to so called "100 year flooding events" occurring multiple times in a decade. No matter what the cause, no one can predict the future, all they can do is look at prior trends and project them into the future and the current trend is higher average sea level and more significant storms leading to storm surges.. Of course if someone believe in the "end times" and plan to be risen up into heaven "momentarily" then I suppose there is no corporeal future to worry about for themselves and any future generations and this discussion is moot.
Of course man contributes to the problem like many actions that were done 100's of years ago it subsequently was determined that it was bad idea Filling in shoreline to expand available land area is now regarded as a pretty dumb idea and its rarely practiced or allowed in most areas. Coastal hardening and barriers have been proven to effectively just shift the damage to areas that are unprotected.
. I have heard that despite the lack of regulations on height of mechanical and major electrical equipment that developers of new buildings are now putting the mechanical rooms on the third story or above so the expensive equipment doesnt get flooded. The old standard was to put mechanical equipment well below ground. Projections I have seen are the combination of sea level rise and increased storm surge yields a recommendation to put critical equipment 25 feet above the current mean sea level. There are various maps and aerial photos of the impact of sea level rise of Boston, its scary how much of the city will get flooded during storm surge events. There was a concept floated of building a huge tidal surge dam in Boston Harbor similar to the one being built in Venice Italy and the one in place in London, it was shot down for now but expect it will be coming back after a major Hurricane hit. Note that its not just Boston its all the US coast, Boston is just trying to get ready for it.
