Expert assessment: Sea-level rise could exceed one meter in this century

Nov 22, 2013

In contrast, for a scenario with strong emissions reductions, experts expect a sea-level rise of 40-60 centimeters by 2100 and 60-100 centimeters by 2300. The survey was conducted by a team of scientists from the USA and Germany.

"While the results for the scenario with climate mitigation suggest a good chance of limiting future sea-level rise to one meter, the high emissions scenario would threaten the survival of some coastal cities and low-lying islands," says Stefan Rahmstorf from the Potsdam Institute for Climate Impact Research. "From a risk management perspective, projections of future sea-level rise are of major importance for coastal planning, and for weighing options of different levels of ambition in reducing greenhouse-gas emissions."

Projecting sea-level rise, however, comes with large uncertainties, since the physical processes causing the rise are complex. They include the expansion of ocean water as it warms, the melting of mountain glaciers and ice caps and of the two large ice sheets in Greenland and Antarctica, and the pumping of ground water for irrigation purposes. Different modeling approaches yield widely differing answers. The recently published IPCC report had to revise its projections upwards by about 60 percent compared to the previous report published in 2007, and other assessments of sea-level rise compiled by groups of scientists resulted in even higher projections. The observed sea-level rise as measured by satellites over the past two decades has exceeded earlier expectations.

Largest elicitation on sea-level rise ever: 90 key experts from 18 countries

"It this therefore useful to know what the larger community of sea-level experts thinks, and we make this transparent to the public," says lead author Benjamin Horton from the Institute of Marine and Coastal Sciences at Rutgers University in New Jersey. "We report the largest elicitation on future sea-level rise conducted from ninety objectively selected experts from 18 countries." The experts were identified from peer-reviewed literature published since 2007 using the publication database 'Web of Science' of Thomson Reuters, an online scientific indexing service, to make sure they are all active researchers in this area. 90 international experts, all of whom published at least six peer-reviewed papers on the topic of sea-level during the past 5 years, provided their probabilistic assessment.

The survey finds most experts expecting a higher rise than the latest IPCC projections of 28-98 centimeters by the year 2100. Two thirds (65%) of the respondents gave a higher value than the IPCC for the upper end of this range, confirming that IPCC reports tend to be conservative in their assessment.

The experts were also asked for a "high-end" estimate below which they expect sea-level to stay with 95 percent certainty until the year 2100. This high-end value is relevant for coastal planning. For unmitigated emissions, half of the experts (51%) gave 1.5 meters or more and a quarter (27%) 2 meters or more. The high-end value in the year 2300 was given as 4.0 meters or higher by the majority of experts (58%).

While we tend to look at projections with a focus on the relatively short period until 2100, sea-level rise will obviously not stop at that date. "Overall, the results for 2300 by the expert survey as well as the IPCC illustrate the risk that temperature increases from unmitigated emissions could commit coastal populations to a long-term, multi-meter sea-level rise," says Rahmstorf. "They do, however, illustrate also the potential for escaping such large through substantial reductions of emissions."

Explore further: Scientists develop new method to help global coasts adapt to sea-level rise

More information: B. P. Horton, S. Rahmstorf, S. E. Engelhart, A.C.Kemp: Expert assessment of sea-level rise by AD 2100 and AD 2300. Quaternary Science Reviews (2013). DOI: 10.1016/j.quascirev.2013.11.002

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Maggnus
3.4 / 5 (8) Nov 22, 2013
Hmm, some talking points:

The observed sea-level rise as measured by satellites over the past two decades has exceeded earlier expectations.

Of course Nik the lamp maker knows better.
The survey finds most experts expecting a higher rise than the latest IPCC projections of 28-98 centimeters by the year 2100. Two thirds (65%) of the respondents gave a higher value than the IPCC for the upper end of this range, confirming that IPCC reports tend to be conservative in their assessment.

Damn those scare mongering IPCC authors, not telling us the truth about how, um drastic the, er, lack of , uh sea, er... fooling us..um..damn!
tadchem
1.3 / 5 (14) Nov 22, 2013
"The experts were also asked for a "high-end" estimate below which they expect sea-level to stay with 95 percent certainty until the year 2100." Translation: they are 95% sure sea level rise by 2100 will be LESS than that.
Lurker2358
1.3 / 5 (16) Nov 22, 2013
I don't know what the point in all the belly-aching really is.

Sea level rose by over a foot in the previous century anyway, and has risen more sharply in the relatively recent past.

You all know the energy companies are not going to relinquish control over the energy infrastructure at all, and they are not going to change from Oil, Coal, and Gas as the mainstream power supplies, until they develop a consumer control mechanism for the other forms of energy.

Nobody in congress nor the energy industry wants you to have cheap, affordable energy, of any kind. They want you to be in financial bondage to the needs of the commute, and air conditioner in summer, or the heater in winter.

Once they "Capitalize" renewable energy, that is, figure out how to make more money from it by charging you more, but convincing you it's less, then they'll do those things. If they did it right now, it would be too obvious, and the sheeple might see through it.
freethinking
1.4 / 5 (18) Nov 22, 2013
Someone please Tell Al Gore that sea levels are going to rise. That way he will quit buying shore front mansions from all the carbon credits he is selling.

Anyone want to make a bet with me that in 10 years news article will be..... the expect rise in ocean levels have not occurred yet.
gregor1
1.5 / 5 (17) Nov 22, 2013
Have these "experts" been right about anything yet? I guess the operative word here is 'might' so there's no way we can say they are wrong. I wonder though, if they read this paper http://hockeyscht...has.html
goracle
2.3 / 5 (16) Nov 22, 2013
Have these "experts" been right about anything yet? I guess the operative word here is 'might' so there's no way we can say they are wrong. I wonder though, if they read this paper http://hockeyscht...has.html

You could also wonder if they've read the Weekly World News on the subject. After all, it's available in supermarkets everywhere. Those silly scientists are missing the revelations of Satan's face in a dust cloud, strange apparitions in odd places and other Amazing Discoveries...
runrig
4.2 / 5 (5) Nov 23, 2013
..... I wonder though, if they read this paper http://hockeyscht...has.html

From the papers abstract....
"This deceleration is mainly due to the slowdown of ocean thermal expansion in the Pacific during the last decade, as a part of the Pacific decadal-scale variability, WHILE THE LAND-ICE MELTING IS ACCELERATING THE RISE OF THE GLOBAL OCEAN MASS-EQUIVALENT SEA-LEVEL. Recent rapid recovery of the rising GMSL from its dramatic drop during the 2011 La Niña introduced a large uncertainty in the estimation of the sea level trend, but the decelerated rise of the GMSL appears to be intact." ( MY CAPS).

We've mainly had La Nina/neutral Pacific since ~2005

Also with warm waters to the west there has been enhanced rainfall over NE Oz.
http://phys.org/n...lia.html

"Since 2011, when the atmospheric pattern shifted ……, sea levels have been rising at a faster pace of about 10mm/yr."
Jonseer
1.4 / 5 (14) Nov 23, 2013
Humankind by default will adopt the least espensive, most passive solution to rising sea levels, because it is much cheaper and fits within the paradigms created by our average lifespan.

What we will do is gradually abandon coastal cities and move their functions further inland where they will be safe for at least a century or so much longer than the lives of the people who will make that decision.

As the tides rise to those new structures, they will be abandoned and new ones built further up still.

To think that humankind can act as one in response to global warming is to think of human beings as ants able to unite and face a threat as a single entity.

Unfortunately we are going to do the human thing and each nation will do what's best for it and nothing more.

That means what we should be doing is focusing on handling the changes and adapting to the new world.

All these efforts are just another way the corporatocracy is trying to monetize the crisis to make a profit.
gregor1
1.3 / 5 (16) Nov 24, 2013
So goracle, for you the journal Global and Planetary Change is the equivalent of a trashy paper you're obviously very familiar with called Weekly World News? Do you know the difference between trash journalism and peer reviewed science? This is also from the abstract.
" It is found that the GMSL [Global Mean Sea Level] rises with the rate of 3.2 ± 0.4 mm/yr during 1993-2003 and started decelerating since 2004 to a rate of 1.8 ± 0.9 mm/yr in 2012. This deceleration is mainly due to the slowdown of ocean thermal expansion in the Pacific during last decade, "
I guess it's interesting to know what 90 cherry picked experts think but, with science, we actually like to have real World evidence.
VendicarE
5 / 5 (4) Nov 24, 2013
Those silly scientists are missing the revelations of Satan's face in a dust cloud, strange apparitions in odd places and other Amazing Discoveries...

http://www.thegua...ightings
goracle
2.4 / 5 (14) Nov 25, 2013
So goracle, for you the journal Global and Planetary Change is the equivalent of a trashy paper you're obviously very familiar with called Weekly World News? Do you know the difference between trash journalism and peer reviewed science? This is also from the abstract.
" It is found that the GMSL [Global Mean Sea Level] rises with the rate of 3.2 ± 0.4 mm/yr during 1993-2003 and started decelerating since 2004 to a rate of 1.8 ± 0.9 mm/yr in 2012. This deceleration is mainly due to the slowdown of ocean thermal expansion in the Pacific during last decade, "
I guess it's interesting to know what 90 cherry picked experts think but, with science, we actually like to have real World evidence.

You omit the blog that you linked to, which is what I referred to. Why change the context? Hiding some cherry-picking or distortion of your own?
goracle
2.4 / 5 (14) Nov 25, 2013
From another one of the denialist rags that masquerade as science journals:
"Why Climate Models are Unscientific Fabrications
24 Nov, 2013 - Anonymous Geophysicist"

Anonymous Geophysicist? This is what some portray as peer reviewed science. The links below that teaser were standard, long debunked talking points. I won't bother to link to it.
The Alchemist
1.1 / 5 (14) Nov 25, 2013
The Change in the State of the Earth over 30 Years

Interesting discovery: The amount of heat absorbed by the Earth's retreating ices, is the same as the heat necessary to raise the Earth's temperature:
3.61e12 cm2 ocean area
X 6 cm change in ocean height/depth
2.166e13 cm3 ice melt volume
x
333.55 j/g to melt ice
7.22e15 joules absorbed by Earth ocean-30 year
2.41e14 joules/year
Notes: Heat is absorbed by ice, mollifying heating
Low-density (non-saline) meltwater flows into oceans, cooling them

X 5.27e19 Earth's atmosphere's mass kg
1000 j/kg (K)
X 0.15 K (increase in temperature in 30 years)-NASA
7.9e15 joules absorbed by Earth atm-30 year
2.63e14 joules/year

Note: This is a very interesting result, as the Earth will radiate heat nightly.
That there is persistence indicates a source of heat.
Greenhouse gases contribute in an obvious way.

Note the Earth's energy state has been changing by more than 4+4.4 = 8.4 Hiroshima type nuclear bombs worth of energy every yea
Steve Case
1.3 / 5 (14) Nov 25, 2013
Sea Level Could Exceed One Meter by 2100?

Current rate is 2.9 mm/yr [probably a good deal less] and shows no sign of acceleration which means only a third of a meter at best by 2100
Modernmystic
1.7 / 5 (12) Nov 25, 2013
As someone who thinks AGW can't be more plain that the world is round I'd also like to pause and take a step back, and be clear what we're talking about and why.

Sea level rise is of immense concern for human beings, especially those in coastal cities, which, if I'm not mistaken is between 600 million to 3 billion people depending on "who you ask".

HOWEVER, as far as "the planet" is concerned it is well to keep in mind that the Earth has gone most of its geologic history without ice caps. Let's be clear. We're talking about saving human beings here and saving human misery...not "the planet" (whatever that is supposed to mean).
freethinking
1 / 5 (15) Nov 25, 2013
Just curios if anyone else has noticed that PHYSORG is ignoring Obamacare mess?

Why is the biggest health care story being ignored by PHYSORG? 10+ million people have lost their health care insurance.
Why is the biggest government technology mess being ignored by PHYSORG?

Just one more question..... if Obama was a white conservative, and this happened on his watch, would PHYSORG ignore these stories as well?

Just asking.....
Steve Case
1 / 5 (12) Nov 25, 2013
Modernmystic said:

"Sea level rise is of immense concern for human beings, especially those in coastal cities,"

Yes, were the oceans rising by centimeters each year ever faster and faster, it would be of great concern. But it's not.

You can Google this title:

"Why has an acceleration of sea level rise not been observed during the altimeter era?"

R.S. Nerem and others from Colorado University's Sea Level Research Group put that presentation together in 2011. It's finding of a negative rate in the acceleration of sea level rise is still valid today.

Here's a screen shot from that presentation showing the negative -0.06 mm/yr² rate in acceleration at that time.

http://oi39.tinyp...14bq.jpg
ForFreeMinds
1 / 5 (13) Nov 25, 2013
Maybe the sea level could rise, creating winners/losers depending on where you live, what property you own, and what you do for a living. Their climate models are flawed and don't reflect reality, so why base any thing on it?

Besides, while nature will create winners/losers, why should government get involved and try to "fix" nature's (or God's in case you're a believer) selections of losers, and make winners pay for loser's losses? Apparently those in government don't even consider adapting to change. Politicians use fear of change, to get power. And then they can't stop nature's changes on a global level anyway. If they do, the problems they create will be worse than "problems" they say exist and must be dealt with.
Modernmystic
1.7 / 5 (11) Nov 25, 2013
Maybe the sea level could rise, creating winners/losers depending on where you live,


Depending on where you live? Depending on where you LIVE?

Do you really think that 3 billion people are going to be content to just hang? If you live at 7000 feet in the Andes you will LOSE too...count on it.
The Alchemist
1.4 / 5 (10) Nov 28, 2013
@Modernmystic
You have a good point.
Also consider how much more energy is put into storms and tsunami from just a little water.
6 cm is what the height is risen now. Say that is 0.03m of height more energy.
0.03m x 0.001 kg x 10000/m2(cm2) = 3 joules/m2

Not alot, until you multiply it by the area of a storm.
Not alot until you consider the waves.
____________
Dec 02, 2013
This comment has been removed by a moderator.