
Global Sea Level Rise Map - perugolate
http://geology.com/sea-level-rise/
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mikeash
It seems to me that maps like this are not very useful, and understate the
problem. They treat sea level as something that only varies over long periods
of time, ignoring daily and weekly variations.

The major problem with a 1m sea level rise isn't that land which is currently
1m above sea level becomes permanently flooded. The major problem is that land
which is 2m or 3m or 4m above sea level becomes flooded way more often.

Local sea levels vary with winds, tides, and perhaps more importantly storms.
A smallish rise in sea level might mean that catastrophic storm surge goes
from a 500-year event to a 10-year event (numbers pulled out of my nether
regions, just meant to illustrate the idea).

For example, much of the damage from Hurricane Sandy was caused by its huge
13ft storm surge. If sea level rises by 1m, then a storm with only 10ft storm
surge will match it, which means damage on that level will happen way more
frequently, and a repeat of Sandy would be _vastly_ more damaging.

I think what a map like this needs is a setting which shows where the (for
example) 100-year flood level is now, and where it moves with the given sea
level rise. This is way more complicated, of course, but would do a much
better job of showing the real problems.

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Phemist
To see what an x-metre sea drop looks like - [https://what-
if.xkcd.com/53/](https://what-if.xkcd.com/53/)

~~~
legulere
There used to be a place called Doggerland in Europe:
[https://en.wikipedia.org/wiki/Doggerland](https://en.wikipedia.org/wiki/Doggerland)

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mzahir
This map is not accurate. I tested by looking at the Maldives, of which the
highest point is only 2.4m above the sea level but even at 7m, the map
indicates that some islands would be above the surface.

~~~
xutopia
Sea rise is not distributed equally around the globe though.

[https://en.wikipedia.org/wiki/Tidal_range](https://en.wikipedia.org/wiki/Tidal_range)

I happen to have visited both extremes (Caribbeans and the Bay of Fundy).

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rbanffy
For the Rio de Janeiro region, at least, it seem it is using the top of the
buildings as if it were the ground level. That makes for very optimistic
forecasts.

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tristanj
I found a bug. According to the map, if sea levels rise by 1 meter then both
Death Valley and the Salton Sea will be completely flooded. But if there's a 0
meter sea level rise, they remain unflooded. I guess relying elevation maps
does not give the whole story.

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frobozz
"Note: Some inland depressions, such as the Caspian Sea, show inundation on
the map but would not be flooded. This is because the mapping algorithm is
based upon elevation and can not distinguish areas that are separated from the
oceans by a ridge or other high area. Be sure that you trace a connection with
the ocean before assuming the area would be flooded. "

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brudgers
Original: [http://flood.firetree.net/](http://flood.firetree.net/)

Description: [http://blog.firetree.net/2006/05/18/more-about-flood-
maps/](http://blog.firetree.net/2006/05/18/more-about-flood-maps/)

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danielvf
This map's default setting of a +7 meter rise would be reached in the year
4348 if sea levels continue to rise at the current rate.

(You can get current and historical sea height satellite data from
[http://sealevel.colorado.edu/](http://sealevel.colorado.edu/))

~~~
Gravityloss
There are reasons to assume that a linear fit is not smart.

If you assume the _rate_ of melting is roughly proportional to the
temperature, then we are in for an increase in rates.

But there are other things. Nonlinear ice effects - that are not very well
included in IPCC projections, could cause a lot more sea level rise sooner.
They are hard to predict.

[http://phys.org/news/2015-09-eyes-oceansjames-hansen-
sea.htm...](http://phys.org/news/2015-09-eyes-oceansjames-hansen-sea.html)

~~~
danielvf
Because we are talking about such tiny numbers when we are talking about the
current sea level rises, anything spectacular in the future has to be non
linear in nature or it just would not matter.

It amazed me just how linear historical sea levels have been. Take a look at
measured New York sea levels, which have been kept since before the Civil War.

[http://tidesandcurrents.noaa.gov/sltrends/sltrends_station.s...](http://tidesandcurrents.noaa.gov/sltrends/sltrends_station.shtml?stnid=8518750)

~~~
Gravityloss
Basically there are a few dangerous ways glaciers can react nonlinearly,
raising sea level (from watching a few videos).

Perhaps best is to watch this long presentation by Eric Rignot from NASA JPL a
few times, it's very fascinating and also terrifying.

[https://www.youtube.com/watch?v=3p9uRxX95f4](https://www.youtube.com/watch?v=3p9uRxX95f4)

Imagine two kilometers of glacier sitting on bedrock that's 500 meters below
sea level. The glacier doesn't touch sea water because there's higher ground
between it and the sea, though still below sea level, and also that's blocked
by ice. If that blocking ice melts, the warm and salty water can then touch
the big glacier that then starts melting and calving icebergs. Or if the
glacier is on higher ground, it can start directly sliding towards the sea.

There are multiple glaciers in Greenland and Antarctica that each could
contribute one meter to sea level rise, that the scientists are watching. Eric
Rignot named the parts between the glacier and the sea Flood Gates.

We haven't observed ice sheet collapses, so it's hard to know how it will play
out, how long it will take, one or more centuries. We also can't afford to
wait and observe them and only then do something about it.

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stronglikedan
Neat! Here I thought I was sufficiently inland in South Florida. I never even
considered that the Everglades would flood me out before the Atlantic did.
Heck, my parents house near the beach would fare better than mine near the
Everglades, _and_ those lucky dogs would get beachfront property while mine
was completely underwater!

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arca_vorago
I want this but more detailed and for sea level drops. I think due to rising
water levels there is a massive amount of underwater archeological finds that
havent been properly found simply due to a misunderstanding of where
coastlines used to be at in the ancient past.

~~~
markild
Relevant: [https://what-if.xkcd.com/53/](https://what-if.xkcd.com/53/)

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vedaprodarte
People who doubt the doubt the accuracy of this map should check their brain.
It is only a simulation based on some assumptions, not facts! If you do not
satisfy with it, go and find 60M+ of water and pour it in your country.

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miseg
Are there any predictions for the next X-years of how high the seas might
rise?

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danielvf
The currently quoted number in policy papers is around 1 meter in the next 100
years. The includes the assumption that sea level rise is accelerating beyond
historical trends.

For fun, you can get sea level rise satellite data for the past 20+ years from
[http://sealevel.colorado.edu](http://sealevel.colorado.edu) and run your own
math. If you just naively run forward the observed rate over the last 22
years, you get 1 meter of rise in 300 years.

You can also see historical tide data for cities here
[http://tidesandcurrents.noaa.gov/sltrends/sltrends_station.s...](http://tidesandcurrents.noaa.gov/sltrends/sltrends_station.shtml?stnid=8518750)

It's important to know that tide data combines sea level information with
information on how much the city is sinking. A bedrock city like NYC will give
you better data on sea level rise than a city built on mud, like Venice, which
is going into the water even if global sea levels were falling instead of
rising.

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danvesma
i heard more like 0.55m in the next 100 years

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danielvf
You are correct. That's far more likely, and probably still too high.

The one meter over 100 years figure is the worst case number in the reports.
Of course the bigger number gets the most press.

The last one hundred years have had a .10 to .20 meter rise, depending on who
you ask.

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shaurz
Nothing to worry about then... I'm still above water and +60m, but the city
centre has flooded.

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perugolate
Doesn't look good for the Netherlands...

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Udik
Well, at least part of the Netherlands (approx. 26%) are _already_ below sea
level. And it doesn't look that bad.

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pavlov
Netherlands is protected by dams. The solid geology of the area has allowed
for durable dams to be constructed over centuries.

Places like Florida are going to be severely hit by rising sea levels because
so much of the land is porous. You can't build a dam to stop the sea if it
seeps in from underground.

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perugolate
Just out of interest, how tall are the dams?

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pavlov
The dams in the famous Zuiderzee Works [1] are about 13m high, it seems.

[1]
[https://en.wikipedia.org/wiki/Zuiderzee_Works](https://en.wikipedia.org/wiki/Zuiderzee_Works)

