World sea levels started rising for unknown reasons about 1860. Graphs showing this:
“Sea-Level Rise from the Late 19th to the Early 21st Century” (Church, White, 2011):
The total rise in mean global sea level from 1880 to 2009 was 210 mm. The average trend over that period was 1.5 mm per year: Sea-Level Rise from the Late 19th to the Early 21st Century | Surveys in Geophysics
Started? Or was that when they first started meaningful measuring?
And what do you mean by “unknown reasons”? Unknown in 1860? Because we’re pretty sure we’ve got a handle on it now.
The worldwide seas levels have been rising and falling since the start of time. 10-15 thousand years ago the sea levels were 300-600 feet lower than now. Britain was connected to Europe by a vast valley and North America and Asia were connected. Sea levels have also been higher than they have now.
Additionally anyone who lives near the coast knows there are tides, higher tides and then there are very high tides. So on a daily scale the sea levels rise and fall.
On a geologic scale the sea levels are constantly changing. On a daily scale sea levels are constantly changing.
To say the sea levels started to change in one specific year is incorrect.
Indeed, but joema’s links show that sea levels have indeed risen.
All the evidence of the effects of sea level rise on human habitations is … you know… underwater right now …
Probably sea levels have been rising since the end of the “Little ice age” around 1400. There is a bay in Alaska (Glacier Bay) that was ice-locked as recently as 1800 but is now open. So the real question is: has the rate of rise increased substantially recently?
The one datum I have is this. I have vacationed in Barbados every winter since 2001. There were certain walks along the sea shore that I could do for the first several years that are now blocked by the ocean. To be sure, I had to time those walks for low tide; they were always blocked at high tide. Even more interesting in a way is that when I look at tidal charts, almost all of the low tides, except at new and full moon, are above the so-called mean sea level. There is a sand bar near where I swim that is shown on the maps, but I have never seen it even at a full moon low tide. Has the island been sinking? I doubt it because it is a coral island uplifted by a volcano and I see no reason it could sink.
The critical takeaway is that the rate of rise has increased dramatically in recent years. Look at joema’s last link:
The rate since 1993 is nearly double the average, and therefore is many times what it was at the beginning of the rise.
One technical note. The earlier Wikipedia links are drawn from that last link, and those graphs are shown in sections 3 and 4. They go back to 1860, but the 1860-1880 data appear exceedingly wonky, probably why the authors start from 1880 in the above quote from the abstract.
But to say that they have risen significantly since 1860 is entirely correct.
The fact that sea levels have fallen and risen over geologic time is irrelevant if you are deciding to purchase beachfront property in Florida. Sea levels are certainly rising now.
Note that only about half of rising sea levels can be attributed to the melting of ice caps and glaciers. About half is due to thermal expansion of the water in the oceans as they warm up.
As is Norfolk.
However, this isn’t due to sea level increases-well I guess some of it is. But in a few places along the US East coast, the land along the coast is sinking due to the after-effects of the last ice age. The ground is still rebounding inland, and like a see-saw the other end is going down.
Lots of articles available. Here is one non-technical one.
http://www.bayjournal.com/article/land_subsidence_leaves_chesapeake_region_with_sinking_feeling
Poor Venice.
I visited Venice a few years ago and was told that the problem with Venice was more to do with them extracting too much groundwater, causing the place to sink.
That issue was addressed decades ago.
A lot of damage had already been done, but that is no longer a contributing factor (all the wells have been capped).
It’s even more easily debunked by simply considering the source. The Faily Caller is Fucker Carlson’s website, so there really isn’t any truth on it anyway.
Here’s some stuff from NOAA
About water levels changing: Climate Change: Global Sea Level | NOAA Climate.gov
A map which shows the sum of land movements and sea level changes: Sea Level Trends - NOAA Tides & Currents
More perspective on the practical impacts of smaller sea level rises that haven’t yet inundated cities on nice days: Coasts | U.S. Climate Resilience Toolkit
Best username/location combo of the week …
Who/Which is that?
ETA: I *think *I get it. You’re thinking LSL stands for something associated with sea level. Like maybe “less than sea level”. Very funny. Not true though.
Or at least it wasn’t when I picked the name. Check back with me in 100 years and it might have come to mean something else. 
Maybe it’s a subject/location connection … like someone from Pripyat discussing nuclear power plant safety …
That’s interesting. I’m in Charleston very occasionally (last time was less than 2 weeks before Dylan Roof) and I didn’t realize that they had any street flooding at high tides.
(Some googling dug up an article on what Charleston may be like in the dystopic year of 2017.)
(ETA: Oh, wait–that is 2107–that makes the article less silly.)
About 3 miles from me on the barrier island is a ritzy area full of 75 foot yachts and $20M ocean-front houses. Their docks and the main road go 6"+ underwater at every extra-high tide. So a dozen times a year clustered in a couple of week-long bouts.
The locals are quite upset, and demand that somebody else pay to solve this. Without any ugly seawalls.
Sigh …
And so it will go nationwide as ever larger fractions of the populace are confronted monthly, then weekly, then daily with the incontrovertible evidence that things are changing.