Sea-level rise could nearly double over earlier estimates in next 100 years

March 30, 2016
Ice cliff at the terminus of Helheim Glacier, Greenland in August 2014. Credit: Knut Christianson

A new study from climate scientists Robert DeConto at the University of Massachusetts Amherst and David Pollard at Pennsylvania State University suggests that the most recent estimates by the Intergovernmental Panel on Climate Change for future sea-level rise over the next 100 years could be too low by almost a factor of two. Details appear in the current issue of Nature.

DeConto says, "This could spell disaster for many low-lying cities. For example, Boston could see more than 1.5 meters [about 5 feet] of in the next 100 years. But the good news is that an aggressive reduction in emissions will limit the risk of major Antarctic retreat."

With mechanisms that were previously known but never incorporated in a model like this before, added to their ice-sheet model to consider the effects of surface melt water on the break-up of and the collapse of vertical ice cliffs, the authors find that Antarctica has the potential to contribute greater than 1 meter (39 inches) of sea-level rise by the year 2100, and greater than 15 meters (49 feet) by 2500 if atmospheric emissions continue unabated. In this worst case scenario, atmospheric warming (rather than ocean warming) will soon become the dominant driver of ice loss.

The revised estimate for sea-level rise comes from including new processes in the 3-dimensional ice sheet model, and testing them against past episodes of high sea-levels and ice retreat.

The researchers find that "ocean-driven melt is an important driver of Antarctic ice shelf retreat where warm water is in contact with shelves, but in high greenhouse-gas emissions scenarios, atmospheric warming soon overtakes the ocean as the dominant driver of Antarctic ice loss." Further, they find that if substantial amounts of ice are lost, the long thermal memory of the ocean that will inhibit the ice sheet's recovery for thousands of years after greenhouse-gas emissions are curtailed.

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David Pollard, senior research scientist in Penn States Earth and Environmental Systems Institute describes his research on Antarctic ice-sheet melting. Credit: Penn State

DeConto and Pollard's study was motivated by reconstructions of sea level rise during past warm periods including the previous inter-glacial (around 125,000 years ago) and earlier warm intervals like the Pliocene (around 3 million years ago). These high sea levels, ranging from a few meters to 20 meters above today, imply that the Antarctic Ice Sheet is highly sensitive to climate warming.

"So, at a time in the past when global average temperatures were only slightly warmer than today," says DeConto, "sea levels were much higher. Melting of the smaller Greenland Ice Sheet can only explain a fraction of this sea-level rise, most which must have been caused by retreat on Antarctica."

To investigate this, DeConto and Pollard developed a new ice sheet-climate model that includes "previously under-appreciated processes" that emphasize the importance of future atmospheric warming around Antarctica.

They explain that, "to date, research into Antarctic ice sheet vulnerability has focused on the role of the ocean, melting floating ice shelves from below. The ice shelves that fringe the land-based ice hold back the flow of inland ice to the ocean. However, it is often overlooked that the major ice shelves in the Ross and Weddell Seas and the many smaller shelves and ice tongues buttressing outlet glaciers are also vulnerable to atmospheric warming."

They add, "Today, summer temperatures approach or just exceed 0 degrees C. on many shelves, and due to their flat surfaces near sea level, little atmospheric warming would be needed to dramatically increase the areal extent of surface melting and summer rainfall."

"If protective ice shelves were suddenly lost in the vast areas around the Antarctic margin where reverse-sloping bedrock (where the bed on which the ice sheet sits deepens toward the continental interior, rather than toward the ocean) is more than 1,000 meters deep, exposed grounding line cliffs would quickly succumb to structural failure as is happening in the few places where such conditions exist today," the researchers point out.

Explore further: Warming ocean water undercuts Antarctic ice shelves

More information: Contribution of Antarctica to past and future sea-level rise, Nature, nature.com/articles/doi:10.1038/nature17145

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33 comments

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Bongstar420
1.3 / 5 (13) Mar 30, 2016
Wooooaaaaa!

There is not a time in the past when temps were higher and humans were not dumping CO2 into the atmosphere...Our climate is "unprecedented"

;)
BartV
1.4 / 5 (19) Mar 30, 2016
Climate alarmists at work again. They have been barking "WOLF" for way too long.

howhot2
4.6 / 5 (20) Mar 30, 2016
And we climate alarmists will continue to bark "WOLF" until you idiot morons rightwing fruit cakes listen to us! Admit the truth you gray naval hair republican operative, you don't know jack about anything and you just say what ever BS looks right in the minds of the ignorant GOPers.
unrealone1
1 / 5 (14) Mar 30, 2016
The earth has been cooling for 10 000 years. Easy search..
Da Schneib
5 / 5 (10) Mar 30, 2016
The global warming denial cargo cult goes on.

Car-GO! Car-GO! Car-GO! thumpa thumpa thump.

I saw that the article on this actually made the top stories on Google News today. People are starting to pay attention.
howhot2
5 / 5 (7) Mar 30, 2016
There you go; @unrealone1 says Earth has been cooling for 10 000 year. Hay BOZO, How much has it cooled? 1) As much as my butt buddy says. 2) As much as I want 3) As much as I'm told by FOX News. 4) As much as my House Rep says. 5) -100F. 6) -10C 7) 1C 8) -1.24K 9) 100F 10) 10C 11) I really am a BOZO. 12) my wife said it and I forgot.

So what is your answer? Please answer in the name of science! Science!

tblakely1357
1.5 / 5 (15) Mar 31, 2016
Strange, early predictions by the Global Warming 'experts' stated that our coastlines should already be several feet underwater. Must be nice to get funding and fame for a theory that is unfalsifiable.
howhot2
5 / 5 (8) Mar 31, 2016
twinkle toes @tblakely1357 claims
Strange, early predictions by the Global Warming 'experts' stated that our coastlines should already be several feet underwater. Must be nice to get funding and fame for a theory that is unfalsifiable.
Have you ever seen an ice cube melt on a plate? Think land is the dry area.

Search string; "google map sea level rise"
Da Schneib
5 / 5 (12) Mar 31, 2016
Here we go again with the global warming denial cargo cult.

Teh evul sciencetis is gettin teh research grants and doing teh fake sciemse to get teh research grants and butttheresnoglobulwarming.

I love the smell of burning stupid in the morning.
howhot2
5 / 5 (8) Mar 31, 2016
Strange, early predictions by the Global Warming 'experts' stated that our coastlines should already be several feet underwater. Must be nice to get funding and fame for a theory that is unfalsifiable.
So your answer is 11)
SteveS
5 / 5 (11) Mar 31, 2016
Strange, early predictions by the Global Warming 'experts' stated that our coastlines should already be several feet underwater. Must be nice to get funding and fame for a theory that is unfalsifiable.


Very similar to your comment on this thread

http://phys.org/n...ars.html

When the whole Global Warming scam started 20 or so years ago the 'experts' stated that our coastlines would be several feet underwater by now.


So I'll ask you again

This is news to me. I'll be interested in any evidence you have that any expert claimed 20 years ago that sea levels would rise several feet by 2016, or you could just retract the statement and admit you were mistaken.
michael_frishberg
5 / 5 (8) Mar 31, 2016
We have LEARNED more about climate in the past 5 years than in the prior 500.

Anyone scratching themselves and claiming some early prediction doesn't match reality, or this is a hoax (ask Exxon Mobil, they participated in an actual hoax), or, it's science biased by the researcher's conviction that climate change is real so it's all about grant money, has no idea what is now known.
Phys1
5 / 5 (9) Mar 31, 2016
Climate alarmists at work again. They have been barking "WOLF" for way too long.


Go back reading the watchtower Bart.
antialias_physorg
5 / 5 (11) Mar 31, 2016
And we climate alarmists will continue to bark "WOLF" until you idiot morons rightwing fruit cakes listen to us! Admit the truth you gray naval hair republican operative, you don't know jack about anything and you just say what ever BS looks right in the minds of the ignorant GOPers.

Succinct, if somewhat mildly put.
antigoracle
1.3 / 5 (13) Mar 31, 2016
Penn State, the domain of Mann made GloBULL warming.
How convenient that they omit the fact that they can only find GloBull warming only where there is known geothermal activity.
antigoracle
1.3 / 5 (12) Mar 31, 2016
I love the smell of burning stupid in the morning.

Hmm... I did wonder why you so enjoy expressing your ignorance on this forum. Thanks for sharing.
SteveS
5 / 5 (12) Mar 31, 2016
@unrealone1

The earth has been cooling for 10 000 years. Easy search..


Which should make you ask the question 'why has it suddenly started warming so fast now?'
Phys1
5 / 5 (9) Mar 31, 2016
Penn State, the domain of Mann made GloBULL warming.
How convenient that they omit the fact that they can only find GloBull warming only where there is known geothermal activity.

How convenient that you slip in this oversimplification without proof.
Phys1
5 / 5 (8) Mar 31, 2016
@unrealone1

The earth has been cooling for 10 000 years. Easy search..


Which should make you ask the question 'why has it suddenly started warming so fast now?'

And it makes wonder why he doesn't.
antigoracle
1.5 / 5 (8) Mar 31, 2016
Penn State, the domain of Mann made GloBULL warming.
How convenient that they omit the fact that they can only find GloBull warming only where there is known geothermal activity.

How convenient that you slip in this oversimplification without proof.

Here, get someone with a brain to read and explain it to your over simple mind.
http://www.nasa.g...n-losses
runrig
5 / 5 (9) Mar 31, 2016
Strange, early predictions by the Global Warming 'experts' stated that our coastlines should already be several feet underwater. Must be nice to get funding and fame for a theory that is unfalsifiable.


Complete and utter bollocks....

"under the IPCC business as usual emissions scenario, an average rate of global mean sea level rise of about 6 cm per decade over the next century (with an uncertainty range of 3 – 10 cm per decade), mainly due to thermal expansion of the oceans and the melting of some land ice. The predicted rise is about 20 cm ... by 2030, and 65 cm by the end of the next century."

https://en.wikipe...t_Report

"several feet" and "by now" my arse.

No FAR said 8 ins by 2013 (14 years away).

Do you actually believe the rubbish you glean from sceptic Blogs?
Or are you here to just Troll?

Tangent2
5 / 5 (7) Mar 31, 2016
Penn State, the domain of Mann made GloBULL warming.
How convenient that they omit the fact that they can only find GloBull warming only where there is known geothermal activity.

How convenient that you slip in this oversimplification without proof.

Here, get someone with a brain to read and explain it to your over simple mind.
http://www.nasa.g...n-losses


That article that you referenced has nothing to do with what you were mentioning about geothermal activity. In fact, the article even acknowledges the sea level rise.
BTW, I love how some people will call mainstream institutions the devil, and yet use their articles/research as footnotes in their bs theories. Hypocrite much?
antigoracle
1.4 / 5 (9) Mar 31, 2016
You got to admire the AGW Cult. You deal with one of their Chicken Little idiots and up pops an even bigger one. What part of finding someone with a brain to explain that report to you, did you not understand?
howhot2
5 / 5 (7) Mar 31, 2016
@Antigoracle keeps talking brains like he eats them for breakfast. Brains, Brains, I need to eat me some Brains! I'm sure he has a nutritional need for all of them brains, but it's not making him any smarter. His arguments are like a walking talking republican zombie saying "Must eat brainnnsss". "Liberals", :"AGW cults", "Damn hippies".,,
antigoracle
1.5 / 5 (8) Mar 31, 2016
@Antigoracle keeps talking brains like he eats them for breakfast. Brains, Brains, I need to eat me some Brains! I'm sure he has a nutritional need for all of them brains, but it's not making him any smarter. His arguments are like a walking talking republican zombie saying "Must eat brainnnsss". "Liberals", :"AGW cults", "Damn hippies".,,

As I was saying.. out poops another one.
runrig
5 / 5 (9) Apr 01, 2016
Strange, early predictions by the Global Warming 'experts' stated that our coastlines should already be several feet underwater. Must be nice to get funding and fame for a theory that is unfalsifiable.


Complete and utter bollocks....

"under the IPCC business as usual emissions scenario, an average rate of global mean sea level rise of about 6 cm per decade over the next century (with an uncertainty range of 3 – 10 cm per decade), mainly due to thermal expansion of the oceans and the melting of some land ice. The predicted rise is about 20 cm ... by 2030, and 65 cm by the end of the next century."

https://en.wikipe...t_Report

"should already be several feet underwater" my arse.

IPCC FAR said 8 ins by 2030 (14 years away).

Do you actually believe the rubbish you glean from sceptic Blogs?
IOW: born stupid or did you work at it?
Guy_Underbridge
3.7 / 5 (6) Apr 01, 2016
Recent quote from SciAm:
Princeton University philosopher Harry Frankfurt famously distinguished BS from lying: "It is impossible for someone to lie unless he thinks he knows the truth. Producing bullshit requires no such conviction."
Phys1
5 / 5 (5) Apr 01, 2016
You got to admire the AGW Cult. You deal with one of their Chicken Little idiots and up pops an even bigger one. What part of finding someone with a brain to explain that report to you, did you not understand?

Chucky, you are so nasty. You are the nastiest midget around. Congrats.
philstacy9
1 / 5 (4) Apr 02, 2016
SteveS
5 / 5 (5) Apr 03, 2016
https://stevengoddard.wordpress.com/2016/03/23/falling-sea-level/


Look at the source data before posting links to Steve Goddard, he's known for taking it out of context.

http://tidesandcu...=8534720
http://tidesandcu...=8518750
Shootist
1 / 5 (2) Apr 03, 2016
I'm at 220 feet in central Florida. Waiting for my beach front to magically appear.
my2cts
5 / 5 (3) Apr 03, 2016
You got to admire the AGW Cult. You deal with one of their Chicken Little idiots and up pops an even bigger one. What part of finding someone with a brain to explain that report to you, did you not understand?

You are such a bore.
leetennant
4 / 5 (4) Apr 04, 2016
https://stevengod...a-level/


Look at the source data before posting links to Steve Goddard, he's known for taking it out of context.


I don't know. I kind of love "No Arctic sea ice decline since 3pm last Tuesday" or "No warming since Feb 5, any other time period is cherry picking" or "No sea level rise since this morning and, you know, I totally looked you guys, I was there at the seaside and it was fine. Here's a graph with no metadata and it's flat and sure the axis goes from 0 - 20m what's your point?".

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