NASA develops tool that shows how much sea level rise coastal cities can expect based on location and degree of ice melt

November 17, 2017 by Bob Yirka, Phys.org report
Gradient Fingerprint Mapping can be used to determine how loss of sea ice will impact sea level rise at a specific location. Credit: Carla Schaffer / AAAS

(Phys.org)—A trio of researchers at NASA's Jet Propulsion Laboratory has developed a new tool to map sea level rise for major cities depending on which parts of the Earth's ice sheets melt and by how much. In their paper published on the open access site Science Advances, Eric Larour, Erik Ivins and Surendra Adhikari describe the tool and the ways it can be used.

As the ice at the poles (and on mountain tops) slowly melts due to global warming, sea levels will rise—that much is obvious. Less obvious is how much rise in different cities will actually experience—this is because the Earth spins (and wobbles) and because there are gravitational differences at different points on the planet—some due to the changes in mass of the ice itself. Because of this, it is difficult to say how much a given will be impacted in the coming years. In this new effort, the team at NASA has made things much easier for city planners. They have created a that accounts for all the factors that will impact sea level changes at various points around the globe over time. The end result is that people responsible for long-term planning for cities that exist on or near the sea now have a tool that they can use to see how much sea levels are expected to rise for their city over a given time-frame.

As one example, the tool shows, the researchers report, that ice melting off the northwest corner of Greenland will have a direct impact on sea levels for London over the course of the next century. New York, on the other hand will be much more impacted by ice melting on the whole northern half of Greenland. Moving south, the tool shows that melting of the northern parts of the Antarctic ice sheet will have a profound impact on Sydney, Australia.

Contribution of glaciers and ice sheet around the world to local sea-level rise in a subset of coastal cities located across all five continents. The movie shows the wide differences in the way ice contributes to sea level according to which city is being considered. Credit: NASA/JPL-Caltech

The researchers describe their tool as offering a sea-level fingerprint for the planet, one that can be modified as conditions change and more is learned about climate change.

The gradient of sea level rise near New York City with respect to ice loss from the Greenland Ice Sheet. Red indicates a larger impact on NYC local sea level rise. Credit: NASA/JPL-Caltech

Explore further: Simulations show likely amount of sea level rise in coastal cities around the world

More information: Eric Larour et al. Should coastal planners have concern over where land ice is melting?, Science Advances (2017). DOI: 10.1126/sciadv.1700537

Abstract
There is a general consensus among Earth scientists that melting of land ice greatly contributes to sea-level rise (SLR) and that future warming will exacerbate the risks posed to human civilization. As land ice is lost to the oceans, both the Earth's gravitational and rotational potentials are perturbed, resulting in strong spatial patterns in SLR, termed sea-level fingerprints. We lack robust forecasting models for future ice changes, which diminishes our ability to use these fingerprints to accurately predict local sea-level (LSL) changes. We exploit an advanced mathematical property of adjoint systems and determine the exact gradient of sea-level fingerprints with respect to local variations in the ice thickness of all of the world's ice drainage systems. By exhaustively mapping these fingerprint gradients, we form a new diagnosis tool, henceforth referred to as gradient fingerprint mapping (GFM), that readily allows for improved assessments of future coastal inundation or emergence. We demonstrate that for Antarctica and Greenland, changes in the predictions of inundation at major port cities depend on the location of the drainage system. For example, in London, GFM shows LSL that is significantly affected by changes on the western part of the Greenland Ice Sheet (GrIS), whereas in New York, LSL change predictions are greatly sensitive to changes in the northeastern portions of the GrIS. We apply GFM to 293 major port cities to allow coastal planners to readily calculate LSL change as more reliable predictions of cryospheric mass changes become available.

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41 comments

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Benni
1.8 / 5 (15) Nov 17, 2017
Scientist Al Gore told us 20 years ago that we should expect significant ocean level rise that by now would have our present coastland areas under water, they are still above water.
Shootist
1.4 / 5 (10) Nov 17, 2017
Sea levels have been rising (they never stopped rising) since the end of the last glaciation.

If this worries you, don't trust the government to save you, start walking, you'll have from decades to centuries to get to high ground.
Ojorf
2.6 / 5 (5) Nov 17, 2017
Benni
1.7 / 5 (12) Nov 17, 2017
Scientist Al Gore told us 20 years ago that we should expect significant ocean level rise that by now would have our present coastland areas under water, they are still above water.


I have a cousin who owns coastland property in northern California that he bought in the mid90s. His property markers are still the same distance from the edge of the ocean as they were back when he bought the property over 20 years ago.
physman
4.6 / 5 (10) Nov 17, 2017
@Benni That settles that then, we can rest easy knowing that Benni's mate says it's fine.
Benni
1.7 / 5 (11) Nov 17, 2017
@Benni That settles that then, we can rest easy knowing that Benni's mate says it's fine.


Hey, they're still looking for your zany relative's DM. Since the last time we talked about you great uncle, astrophysicists have employed DM detection devices 1000 times more sensitive & turned up zero. Poor uncle Zwicky.
eachus
1 / 5 (7) Nov 17, 2017
I keep wondering when the people studying sea level rise and climate change will get a clue. (First note that the Mediterranean has significant rise and fall due to the water flow through the Straits of Gibraltar, but the sinking of Venice is due to pumping water out from underneath the city.) During the last Ice Age ocean levels were over 100 feet (30+ meters) below current levels. The oceans and continents float on the upper mantle. So the continents are rising with respect to the oceans, but more slowly than ocean level rises.

Of course, land masses that were buried under miles of ice during the Ice Age are rebounding faster. This can be seen in Canada, parts of the US, and the British Isles. The British Isles are an interesting special case, since they are tilting (or untilting) at the same time they are rising.

Anyway, when all this recovery finishes, most cities will be higher above sea level than now, except those on the wrong side of nearby subduction zones.
Captain Stumpy
4.4 / 5 (7) Nov 17, 2017
@benjiTROLL
Scientist Al Gore told us
one would think a self-proclaimed "nuclear engineer" would be literate enough to comprehend that Gore is not a scientist...

it's not a matter of supposition as it's freely available information if one is only capable of reading to at least the 6th-grade level
(of course, that may well explain why you're ignorant of this simple fact...)

.

That settles that then, we can rest easy knowing that Benni's mate says it's fine
@Physman
those cursed with fanaticism or stupidity are impervious to this type of humour as it's too far beyond their capacity to comprehend
aksdad
1.4 / 5 (9) Nov 17, 2017
one would think a self-proclaimed "nuclear engineer" would be literate enough to comprehend that Gore is not a scientist

Speaking of being impervious to humor....Benni just pwned you. Of course Al Gore isn't a scientist. That's why it's funny.
aksdad
1.4 / 5 (9) Nov 17, 2017
The current global average rate of sea level rise as measured by satellite telemetry is 3.4 ± 0.4 mm/yr.

http://sealevel.colorado.edu/

Tide gauge data shows it being less than that, closer to 2 mm/yr. The lower chart on the NASA page below (1870–2000) is about 1.5 mm/yr:

https://climate.n...a-level/

The difference between tide gauge (~2 mm/yr) and satellite (~3.4 mm/yr) is due to instrument differences and statistical processing. No significant acceleration in sea level rise is observed over the 147-year tide gauge record. There are, however, brief rate increases corresponding to El Niños followed by sea level decreases afterward as you can see in the first link before and after the big ones in 1998 and 2016. You can also see a decrease in sea levels around major La Niñas, as in 2010–11 and 2012.

2 and 3.4 mm/yr is 8 to 13 inches per century. So far no evidence of catastrophic glacier melt accelerating sea level rise.
aksdad
2 / 5 (10) Nov 17, 2017
If you'd like to see measured sea level rise and historical trends from tide gauges around the world to get an idea how much your coastal city is affected, see the global map on the NOAA Tides and Currents Sea Level Trends page here:

http://tidesandcu...ltrends/

Click on any link to see the data from that station. It's obvious from the map that land subsidence contributes significantly to local sea level change. The land around the Gulf of Mexico is subsiding so rates are higher. The land at high northern latitudes is rising; bouncing back from the mile-thick glaciers that covered them 12,000 years ago at the end of the last ice age, so sea levels are actually decreasing there.
TrollBane
5 / 5 (7) Nov 17, 2017
Meanwhile, regional governments in Nova Scotia are pushing the province and federal government to fix two century old dikes that protect the Trans Canada highway and other infrastructure because Nova Scotia is likely to be cut off from the mainland by rising seas and storm surges in a couple of decades if nothing is done.
Porgie
4 / 5 (4) Nov 17, 2017
If we could only stop California from releasing 10 million tons of CO2 per year. Through forest fires and other mismanaged wild lands.
Steve 200mph Cruiz
1 / 5 (5) Nov 17, 2017
I thought the main driver of sea level rise was the extra heat like mercury in a thermometer
leetennant
4.4 / 5 (7) Nov 17, 2017
I'll be even more fascinated when NASA releases the maps for the tidal surge of bullshit in comments sections since Trump got elected.
Bekim_Bacaj
1 / 5 (9) Nov 17, 2017
This madness must stop!
This is a product of hysteria of mad superstitious people that have infiltrated all Science institutions of the world and it's getting out of hand. It is threatening the foundations of human civilization.
These anti-science articles must be punished, and those who publish them also must bare consequences.
This nonsense must come to an end.
leetennant
5 / 5 (8) Nov 17, 2017
This madness must stop!
This is a product of hysteria of mad superstitious people that have infiltrated all Science institutions of the world and it's getting out of hand. It is threatening the foundations of human civilization.
These anti-science articles must be punished, and those who publish them also must bare consequences.
This nonsense must come to an end.


I'd love to know how you punish an article.
leetennant
4.6 / 5 (10) Nov 17, 2017
Scientist Al Gore told us 20 years ago that we should expect significant ocean level rise that by now would have our present coastland areas under water, they are still above water.


The original IPCC projections for sea level rises were 0.8m by 2100 so, no, this is either a lie or a figment of your imagination

Sea levels have been rising (they never stopped rising) since the end of the last glaciation.


This clearly shows this statement is not true
https://www.giss....nitz_09/

I have a cousin who owns coastland property in northern California that he bought in the mid90s. His property markers are still the same distance from the edge of the ocean as they were back when he bought the property over 20 years ago.


Even if this were true, it's utterly irrelevant. A single anecdotal data point is not information. This is science of the "But my Dad always said" variety.
leetennant
4.5 / 5 (8) Nov 17, 2017
3.4 mm/yr is 8 to 13 inches per century. So far no evidence of catastrophic glacier melt accelerating sea level rise.


3.4mm per year is around 20cm, which is the current level of sea level rise. A 10cm average rise doubles the risk of flooding in coastal areas and you don't think 20cm is of any concern? The current rate of projected sea level rise is double the rate of initial IPCC projections. And yes, that's pretty catastrophic.

It seems you slept through 2017. Sea level rises are first most noticeable in storm surge and levels of flooding. Now tell me how many record floods and storm surges there were in 2017 in the US alone? Now add in the rest of the world. You're in denial and it's not pretty.
howhot3
5 / 5 (5) Nov 17, 2017
I'll be even more fascinated when NASA releases the maps for the tidal surge of bullshit in comments sections since Trump got elected.


So true, and the tides are mighty high on this one.
Dug
1 / 5 (7) Nov 17, 2017
leetennant. I think 3.4mm is a lot closer to 3.4mm - than it is to 20cm - which isn't the annual sea level rise - its less than 3.4mm. Less than 3.4mm/yr especially if you don't use satellite error adjustments, factor in El Nino and or La Nina effects and or don't include subsidence as sea level rise. See aksdad;s comments above - because of all the bs comments here - his is the closest to actually being correct.
leetennant
4.3 / 5 (6) Nov 17, 2017
leetennant. I think 3.4mm is a lot closer to 3.4mm - than it is to 20cm - which isn't the annual sea level rise - its less than 3.4mm. Less than 3.4mm/yr especially if you don't use satellite error adjustments, factor in El Nino and or La Nina effects and or don't include subsidence as sea level rise. See aksdad;s comments above - because of all the bs comments here - his is the closest to actually being correct.


If sea levels were rising 20cm a year, we'd be Waterworld in less than a decade. 3.4mm/year IS catastrophic. You just don't understand the climate system.
Parsec
4.5 / 5 (8) Nov 17, 2017
Scientist Al Gore told us 20 years ago that we should expect significant ocean level rise that by now would have our present coastland areas under water, they are still above water.


You need to get out more. The ocean has been rising almost exactly as predicted 20 years ago.
leetennant
4.5 / 5 (8) Nov 18, 2017
I thought the main driver of sea level rise was the extra heat like mercury in a thermometer


There are two main sources of sea level rise: the melting of land ice (not sea ice) and thermal expansion (as you said, the extra heat). Considering the volume of water locked up in land ice, the former is going to end up being a far greater driver.
Ojorf
3.8 / 5 (10) Nov 18, 2017
Scientist Al Gore told us 20 years ago that we should expect significant ocean level rise that by now would have our present coastland areas under water, they are still above water.


You need to get out more. The ocean has been rising almost exactly as predicted 20 years ago.


What Gore actually said was that if the Greenland ice sheet collapses large areas of current coast lines will be under water. He did not give a projected time. Check the documentary again.
Benni
1.5 / 5 (8) Nov 18, 2017
Scientist Al Gore told us 20 years ago that we should expect significant ocean level rise that by now would have our present coastland areas under water, they are still above water.


You need to get out more. The ocean has been rising almost exactly as predicted 20 years ago.


And what do YOU say that is? Just put up a number, I don't care about a bunch of indecipherable links, then I'll pass that number on to my cousin who owns coastland property in N California so that he can check to verify his property markers have not been tampered with.
Captain Stumpy
5 / 5 (4) Nov 18, 2017
@idiot benjiTROLL
then I'll pass that number on to my cousin who owns coastland property in N California so that he can check to verify his property markers have not been tampered with
so, your "cousin" has taken regular multi-daily high precision checks with specialised equipment of his property line, especially on the ocean front, for the past few decades?

yeah, i didn't think so
tblakely1357
1 / 5 (6) Nov 18, 2017
'Who are you going to believe, me or your lying eyes?'
leetennant
5 / 5 (7) Nov 18, 2017

And what do YOU say that is? Just put up a number, I don't care about a bunch of indecipherable links, then I'll pass that number on to my cousin who owns coastland property in N California so that he can check to verify his property markers have not been tampered with.


We all knew that you reject climate science because you don't understand it. But I've never before seen somebody use their ignorance with such pride. Are you genuinely using "I don't understand it therefore it must be wrong" as your actual argument? Like, you sat down and went "my ignorance will prove them wrong!".

But I'll get NASA on personalised projections for "your mate's place" right now. That's the only way we'll know for sure!
Benni
1.4 / 5 (9) Nov 18, 2017
And what do YOU say that is? Just put up a number, I don't care about a bunch of indecipherable links, then I'll pass that number on to my cousin who owns coastland property in N California so that he can check to verify his property markers have not been tampered with.


We all knew that you reject climate science because you don't understand it. But I've never before seen somebody use their ignorance with such pride. Are you genuinely using "I don't understand it therefore it must be wrong" as your actual argument? Like, you sat down and went "my ignorance will prove them wrong!".

But I'll get NASA on personalised projections for "your mate's place" right now. That's the only way we'll know for sure!


I asked you something very simple, to give me a number & you launch a personal diatribe? I can only presume that means you don't have a number for N California?
Gimp
1 / 5 (7) Nov 19, 2017
The sky is falling, The sky is falling.
greenonions1
5 / 5 (5) Nov 19, 2017
aksdad
No significant acceleration in sea level rise is observed over the 147-year tide gauge record
But you are also arguing that land movement is affecting the data from tide gauges. In fact there is good data to show that sea level rise is accelerating. Currently around 3 mm per year - previously less than 2 mm per year.

https://tamino.wo...eration/
Benni
1.6 / 5 (7) Nov 19, 2017
aksdad
No significant acceleration in sea level rise is observed over the 147-year tide gauge record
But you are also arguing that land movement is affecting the data from tide gauges. In fact there is good data to show that sea level rise is accelerating. Currently around 3 mm per year - previously less than 2 mm per year.
........then explain why my cousin's property line markers on his N California coastland property have not changed since he bought the property in the mid90s?

greenonions1
5 / 5 (5) Nov 19, 2017
benni
.......then explain why my cousin's property line markers on his N California coastland property have not changed since he bought the property in the mid90s?
Are you arguing that sea levels are not rising? For real? And you are basing that on your cousin's property line markers?
If you really believe that your cousin's property line markers actually prove that sea levels are not rising - you need to write a paper - contact the local media - contact the scientific community - and initiate a study - which will show that all the satellite, and tide gauge, and reconstructional science on the subject are wrong - and cousin Vinny knows the truth....
Captain Stumpy
4.8 / 5 (5) Nov 19, 2017
@benjiTROLL
........then explain why my cousin's property line markers on his N California coastland property have not changed since he bought the property in the mid90s?
because it hasn't been re-surveyed

if you have a surveyed property line it's the same regardless of the year, even if it eventually becomes submerged

if you can't understand the above, perhaps you should read up on the Louisianna purchase survey in the following: White, Albert C. "A History of the Rectangular Survey System." Washington DC: U.S. Department of the Interior, 1926.
TrollBane
5 / 5 (5) Nov 19, 2017
Article on the threat to Nova Scotia: https://www.thegl...7002253/
TrollBane
5 / 5 (6) Nov 20, 2017
"........then explain why my cousin's property line markers on his N California coastland property have not changed since he bought the property in the mid90s?"

Are you implying that your cousin's property represents the entire world? Or is that just the extent of your experience?
leetennant
5 / 5 (7) Nov 20, 2017
"........then explain why my cousin's property line markers on his N California coastland property have not changed since he bought the property in the mid90s?"

Are you implying that your cousin's property represents the entire world? Or is that just the extent of your experience?


I've sent a note to NASA about it. Mapping sea level rise at Benni's mate's place is the only way to be sure.
rini32
5 / 5 (3) Nov 21, 2017
And what do YOU say that is? Just put up a number, I don't care about a bunch of indecipherable links, then I'll pass that number on to my cousin who owns coastland property in N California so that he can check to verify his property markers have not been tampered with.

We all knew that you reject climate science because you don't understand it. But I've never before seen somebody use their ignorance with such pride. Are you genuinely using "I don't understand it therefore it must be wrong" as your actual argument? Like, you sat down and went "my ignorance will prove them wrong!".

But I'll get NASA on personalised projections for "your mate's place" right now. That's the only way we'll know for sure!


Well said this clown (an antigoracle sockpuppet) actually believes with his ignorance he can convince the world of his hilarious ideology.
eachus
5 / 5 (1) Nov 21, 2017
I'd love to know how you punish an article.


Print it out and put it through a shredder. Using it to line a cat box first is extreme and not recommended. ;-)
TrollBane
5 / 5 (2) Dec 03, 2017
"Mapping sea level rise at Benni's mate's place is the only way to be sure." I say we take off and nuke Benni's mates place from orbit. Only way to be sure. ;)

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