Sea levels could rise by more than three metres, shows new study

April 26, 2017
Sea levels could rise by more than three metres, shows new study
Flood defences such as the Thames Barrier must take account of worst-case sea level scenarios. Credit: University of Southampton

Global sea levels could rise by more than three metres – over half a metre more than previously thought – this century alone, according to a new study co-authored by a University of Southampton scientist.

An international team including Sybren Drijfhout, Professor in Physical Oceanography and Climate Physics, looked at what might happen if continue unabated.

Using new projections of Antarctic mass loss and a revised , they concluded that a worst-case scenario of a 2.5 to three-metre was possible by 2100.

Professor Drijfhout said: "It might be an unlikely scenario, but we can't exclude the possibility of rising by more than three metres by the year 2100.

"Unabated global warming will lead to sea-level rise of many metres – possibly more than ten metres – within a few centuries, seriously threatening many cities all over the world that are built in low-lying river deltas. This will also seriously affect the coastline of the UK."

The research – published this month in Environmental Research Letters – is consistent with the National Oceanic and Atmospheric Administration's (NOAA) recent adjustment of its possible future high-end sea-level rise from two to 2.5 metres.

However, the new study integrated different model estimates with a new statistical method, whereas the NOAA estimate relied on expert judgment.

Recent observation and modelling studies have shown the future melt of Antarctica might happen dramatically faster than previously thought.

Professor Drijfhout and scientists at the Royal Netherlands Meteorological Institute, which led the research, took this and other factors – including ocean warming, glacier melt, land water storage and Greenland ice sheet melt – into account to create their projection.

"This is the first time that robust statistical techniques have been used to develop a scenario like this, whereas previous high-end sea level projections have always been based on subjective expert judgment," said Professor Drijfhout.

"It's important for policy-makers and the general public to know what the consequences might be when carbon dioxide emissions are not decreased, especially as there is a severe time-lag between emission-reduction and the response.

"Also, the construction of artificial flood defences need to take account of low-probability events, including the possibility that the international community fails to take adequate measures in reducing measures.

"We should not forget that the Paris Agreement is only a declaration of intention, and that no adequate measures have yet been agreed to turn these intentions into policy."

The team's projection explicitly accounted for three scientific uncertainties – the speed at which the Antarctic ice sheet is going to melt, the speed at which the ocean is warming up, and the amount of emitted greenhouse gases over the 21st century.

Explore further: Regional sea-level scenarios will help Northeast plan for faster-than-global rise

More information: Dewi Le Bars et al. A high-end sea level rise probabilistic projection including rapid Antarctic ice sheet mass loss, Environmental Research Letters (2017). DOI: 10.1088/1748-9326/aa6512

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28 comments

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philstacy9
Apr 26, 2017
This comment has been removed by a moderator.
SteveS
4.2 / 5 (5) Apr 26, 2017
A science fiction plot is not science.


No it isn't, but this is

http://iopscience....iop.org
Munix
not rated yet Apr 26, 2017
Nothing to worry about.

I will be on my super-yacht enjoying the high seas ;-)
Steve Case
5 / 5 (4) Apr 26, 2017
Three meters by 2100 comes to an average of over TEN times the current rate for the next 83 years. The obvious question to ask is when will this dramatic run-up in the rate begin to happen?

Steve Case - Milwaukee, WI
zz5555
4.2 / 5 (5) Apr 26, 2017
Three meters by 2100 comes to an average of over TEN times the current rate for the next 83 years. The obvious question to ask is when will this dramatic run-up in the rate begin to happen

Exponential increase often starts out slow, so it's not surprising that the rate isn't too fast right now. Projections indicate that sea level rise will greatly speed up around mid-century (https://skeptical...sic.html ). Note that we're currently running at the top of projections, so they're certainly correct so far. The continued warming of the ocean and the accelerating loss of ice indicates that we'll certainly get a great deal more sea level rise - especially if we continue to put CO2 in the atmosphere. I don't know if we'll get to 3m of rise, but it's certainly not an outlandish statement.
MR166
2 / 5 (4) Apr 26, 2017
" Projections indicate that sea level rise will greatly speed up around mid-century "

Go pack 20 years or so and tell me how those predictions turned out. Funny how the apocalypse is always 20 years away or just long enough for those making the predictions to retire.
anonieme_x
3.7 / 5 (3) Apr 27, 2017
It really bothers me that even media like phys.org pick out the (highly unlikely) wcs as the most important conclusion of this thorough international scientific research and build the article around it. The most likely scenario is not even mentioned.
I think click bait driven media that only mention the extreme predictions contribute to the polarisation in society, because they do not really provide the public - whatever its position in the matter - with a balanced story of the research findings.

('science fiction plot'? The KNMI is a world leading institute that constantly refines its models with empirical data; this is hardcore science.
I wonder; if someone tried to punch a science denier's nose, would the 'skeptic' still dismiss the scenario where the fist trajectory that - given the ongoing measurements that confirm the trajectory - is obviously on collision course with his nose, as a 'science fiction plot'?)
MR166
2.3 / 5 (6) Apr 27, 2017
Yet the Antarctic continues to gain ice mass and is cooling !
SteveS
4.2 / 5 (5) Apr 27, 2017
Yet the Antarctic continues to gain ice mass

No it doesn't
http://onlinelibr...052/full

and is cooling !

No it isn't
https://www.resea...459_2009
MR166
2 / 5 (4) Apr 27, 2017
SteveS
5 / 5 (4) Apr 27, 2017
https://www.nasa.gov/feature/goddard/nasa-study-mass-gains-of-antarctic-ice-sheet-greater-than-losses

NASA 2016 GRACE Data
https://climate.n...and-ice/
https://sealevel-...3116.csv
http://www.thegwpf.com/antarctic-peninsula-cooled-nearly-1c-during-1999-2014/

There's more to the antarctic than the antarctic peninsula
MR166
1.8 / 5 (5) Apr 28, 2017
In order to keep everyone upset the most highly publicized CO2 reading is taken at a site that is an ACTIVE volcano that spews tons of the stuff . That gives them the opportunity to "adjust" the readings at will.

If they really wanted to have a true gauge of the earths tempurature they would have deployed 10s of thousands of additional measurement stations in remote areas all over the world. This would not be very expensive. Solar cells and satellite internet make this a very easy task. No, they prefer to take most of their readings in populated areas and "adjust" the data as they see fit.
Hat1208
4.5 / 5 (8) Apr 28, 2017
@MR166

Please give a link to this highly unethical practice to prove your point. Other than that STFU.
SteveS
5 / 5 (5) Apr 28, 2017
In order to keep everyone upset the most highly publicized CO2 reading is taken at a site that is an ACTIVE volcano that spews tons of the stuff . That gives them the opportunity to "adjust" the readings at will.

http://scrippsco2...nds.html

Point Barrow, La Jolla, Mauna Loa, Christmas Island, and the South Pole, take your pick, they all show the same thing.
SteveS
5 / 5 (5) Apr 28, 2017
That gives them the opportunity to "adjust" the readings at will.

https://www.esrl....BDioxide
223 data sets from dozens of Countries. So tell me who are the "them" that "adjust the readings at will"?
Hat1208
4.3 / 5 (6) Apr 28, 2017
@Steve S

Thanks for the link. Very interesting that none of these locations give any credence to MR166's claim of biased data from populated areas. From the looks of those locations where the readings were taken not much in the way of population. Although I understand Christmas Island to have a thriving industrial complex, sic.
SteveS
4.4 / 5 (7) Apr 28, 2017
@HAT1208

Thanks, when MR166 posted links to reputable articles on Antarctic mass balance and temperature I had high hopes for a reasonable fact based argument, but then he just reverted back to the same old conspiracist ideation and zombie arguments. :-(

MR166
1 / 5 (4) Apr 29, 2017
zz5555
5 / 5 (5) Apr 29, 2017
Much to my regret, I actually wondered what MR166 was posting and took him/her off ignore. The latest post is to an article on a place called hockeyschtick. (Really, the "hockey stick" has been confirmed over and over and over using independent data. How incompetent do you have to be to keep on about it?) The article claims that a paper shows that some stations are "non-valid" and that only using "valid" stations shows that the Northern Hemisphere temperature was 1C cooler in 2013.

But is there any validity to this claim? It turns out the answer is "No".

cont'd.
SteveS
5 / 5 (3) Apr 29, 2017
http://hockeyschtick.blogspot.com/2015/05/new-paper-finds-large-warming-bias-in.html


https://www.resea..._to_2013

WTF!

Please can everybody read this and tell me how it managed to get published?
zz5555
5 / 5 (4) Apr 29, 2017
To start out with, the paper (http://s3.amazona...mper.pdf ) uses an average of Northern Hemisphere temperatures. But it just uses a straight average of the sites, with no thought of where those sites are. As the paper shows, most of those sites are in the US and northern Europe. So it starts by introducing a cooling bias into the process.

cont'd.

(I hope the link doesn't get screwed up. If it does and you want to see the paper, use scholar.google.com and search for "Extraction of the global absolute temperature for northern hemisphere using a set of 6190 meteorological stations from 1800 to 2013". But I don't recommend it.)
zz5555
4.2 / 5 (5) Apr 29, 2017
Next, he removes "non-valid" sites. But how does he define a non-valid site? If a site is missing a measurement from one month, he removes it from consideration for the whole year. This might be valid if he was averaging annual temperatures. But he averages monthly temperatures. This makes no sense. So areas with less reliable equipment (read: 3rd world nations or areas with wars - that is, the warmer areas in consideration) get moved to the "non-valid" list. So the "valid" list has more of a cooling bias added to it.

He also mistakenly believes that absolute temperature is more important than anomalies. This introduces more of a cooling bias given the preference to the northern latitudes in his study. He also introduces a seasonal bias that, again, neglects the location of the sites with missing data - introducing a cooling bias.

cont'd.
zz5555
4.2 / 5 (5) Apr 29, 2017
The only valid conclusion I can see coming from this paper is: First world nations have more temperature stations and more reliable equipment. Which seems to be worthy of a D'uh! No wonder it only has one citation (and he was also the author of the paper that cited it).

My fault for reading a comment by MR166.
SteveS
4.2 / 5 (5) Apr 29, 2017
http://hockeyschtick.blogspot.com/2015/05/new-paper-finds-large-warming-bias-in.html


http://static.ber...-103.pdf
https://www.resea..._to_2013

MR166 please compare the methodology for the temperature averaging process in these two papers.
zz5555
5 / 5 (3) Apr 29, 2017

WTF!

Please can everybody read this and tell me how it managed to get published?

Danged if I know. It seems he's a PhD candidate in economics (https://www.resea...topoulos ). I don't think he likes relativity or LIGO much, but if you want a hoot, look at his paper on the missing flight MH370 and dark energy (I am not making that up). Doesn't look like it ever got published, though.
SteveS
5 / 5 (3) Apr 29, 2017

WTF!

Please can everybody read this and tell me how it managed to get published?

Danged if I know. It seems he's a PhD candidate in economics (https://www.resea...topoulos ). I don't think he likes relativity or LIGO much, but if you want a hoot, look at his paper on the missing flight MH370 and dark energy (I am not making that up). Doesn't look like it ever got published, though.


http://www.academ...overn_it

He does seem to have an opinion about everything, doesn't make hockeyschtick look particularly good does it.
antigoracle
1.8 / 5 (5) Apr 29, 2017
It might be an unlikely scenario

LMAO....Never mind that NASA has confirmed that the Antarctic is cooling and gaining mass, despite extensive geothermal activity in the west of the continent.
Da Schneib
5 / 5 (4) Apr 29, 2017
@SteveS, well done. Bringing data works well. Unfortunately, data don't swing those untutored in critical thinking, they only affect the perceptions of the trained.

Vote always and ever for teaching of critical thinking skills right along with the alphabet.

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