2-metre sea level rise 'plausible' by 2100: study

The vast ice sheets of Greenland and Antarctica contain enough frozen water to lift the world's oceans dozens of metres
The vast ice sheets of Greenland and Antarctica contain enough frozen water to lift the world's oceans dozens of metres

Global sea levels could rise by two metres (6.5 feet) and displace tens of millions of people by the end of the century, according to new projections that double the UN's benchmark estimates.

The vast ice sheets of Greenland and Antarctica contain enough frozen water to lift the world's oceans dozens of metres. The expansion of water as oceans warm also contributes to .

But predicting the rates at which they will melt as the planet heats is notoriously tricky.

The United Nations' Intergovernmental Panel on Climate Change (IPCC) said its 2013 Fifth Assessment Report that under current emissions trajectories—a "business-as-usual" scenario known as RCP8.5—would likely rise by up to one metre by 2100.

That prediction has since been viewed as conservative, as the levels of planet-warming greenhouse gas emissions continue to rise year on year, and satellites showing accelerated rates of melt-off from massive ice sheets atop Antarctica and Greenland.

A group of the world's leading ice scientists this week released a expert judgement on the situation, drawing on their own experience and observations.

While there was still a significant margin of error, they found it "plausible" that under the business-as-usual emissions scenario, sea-level rises could exceed two metres by 2100.

The authors said the area of land lost to the ocean could be equivalent to that of France, Germany, Spain and Britain combined and would displace more than 180 million people.

"A sea-level rise of this magnitude would clearly have profound consequences for humanity," they said.

'The true risks'

The Paris climate deal, struck between nations in 2015, aims to limit global temperature rises to well below two degrees Celsius (3.6 Farenheit), and encourages countries to work towards a 1.5C cap.

In October the IPCC released a landmark climate report that called for a drastic and immediate drawdown in coal, oil and gas consumption in order to arrest the rapid rise in the levels of greenhouse gases in the atmosphere.

That report, however, did not include revised estimates of sea level rise.

Earth has already heated 1C since pre-industrial times, contributing roughly 3mm to sea levels each year.

The authors of the new study, released Monday in the journal Proceedings of the National Academy of Sciences, argue that the IPCC's sea-level rise prediction was too constrained by focusing on what was "likely" to happen.

At wider probabilities—5-95 percent likelihood—they found that under 2C of warming seas could rise 36-126 cm by 2100.

In world that has warmed by 5C—unlikely but certainly not impossible given projected fossil fuel demand in the coming decades—they calculated a five percent risk of sea levels surpassing two metres higher, topping out at 238 cm.

Willy Aspinall, from the University of Bristol's School of Earth Sciences, said he hoped the study could provide policymakers with a more accurate worst-case scenario "crucial for robust decision making."

"Limiting attention to the 'likely' range, as was the case in the IPCC Fifth Assessment Report, may be misleading and will likely lead to a poor evaluation of the true risks," he added.


Explore further

Expert judgement provides better understanding of the effect of melting ice sheets

More information: Jonathan L. Bamber el al., "Ice sheet contributions to future sea-level rise from structured expert judgment," PNAS (2019). www.pnas.org/cgi/doi/10.1073/pnas.1817205116

© 2019 AFP

Citation: 2-metre sea level rise 'plausible' by 2100: study (2019, May 21) retrieved 24 June 2019 from https://phys.org/news/2019-05-metre-sea-plausible.html
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May 21, 2019
A speculation with a 5% to 95% probability? How is that not useless?

Meanwhile, all such dire alarmist headlines and posts ought to include, for fairness:

1) a list of all the benefits that will come into reality with a warmer world;
2) acknowledgment that even if true, mankind will "move out of the way" of this stupendously slow sea rise... to places where the benefits will be astounding;
3) a link to the science that shows when the next glaciation would return if our species had not evolved.

May 21, 2019
There is NO significant sea level rise anywhere on this planet. This is just fear mongering propaganda! Those ice sheets can't melt any faster and can't melt fast enough to cause any harm because there isn't enough heat to do so. The Sun puts out at max output and the same amount of energy all the time. We would need another Sun to melt the rest of this ice at a faster rate. NASA is nothing but a bunch of frauds!

May 21, 2019
Since the Maldives were predicted to be under water by 2010, and yet they are still above water and flourishing, why would anyone give any credence to these continual conjectures?
I once commented on one of these news sites that houses were falling into the sea in Vancouver due to 'dramatically' rising sea levels, and nobody raised an eyebrow. No one bothered to check to see if the story was true. The sheep all assumed it was true because of the hype regarding rising sea levels.

May 21, 2019
The academic community needs to be purged!!! Peer review now means little more than one hand washing the other. Selling your credentials to the agenda is a heinous crime.

May 21, 2019
It is absolutely mindboggling how this site attracts trolls/braindead zombies who constantly post here denying ANYTHING is going on on this planet regarding warming and its effects. Clearly the above idiots, Donohue, rodkeh, & samb, are pathetic individuals either in the pay of Alec, or some such organization, or just completely bats*** crazy. EVERYWHERE is evidence - DAILY! - that the planet is warming, that it's caused by human activity, and that areas of frozen water are giving up the ice. And they attempt to come off like supercilious know-it-alls fomenting their delusions and lies. Of course, they can't handle the truth.

http://prn.fm/cli...herever/
https://thinkprog...27ab619/
https://www.scien...150.html
https://www.scien...al-flood

May 21, 2019
@Zanrak

[link battle declined ... ]

On the contrary, this type of alarmist headline/post is designed to attract those, like you, who have drunk the alarmist koolaid (which has not yet taken effect) and get triggered by a normal challenge to (not a totalized rejection of) AGW.

Seriously, you always do that. You see a legit challenge, the knee-jerk immediately boots you into hate speech and totalizing.

Answer my challenge: how can a speculation with a 5% to 95% probability not be useless?

May 21, 2019
There is no sea level rise on this planet at this time!!!!!!

May 21, 2019
It is absolutely mindboggling how this site attracts trolls/braindead zombies who constantly post here denying ANYTHING is going on on this planet regarding warming and its effects. Clearly the above idiots, Donohue, rodkeh, & samb, are pathetic individuals either in the pay of Alec, or some such organization, or just completely bats*** crazy. EVERYWHERE is evidence - DAILY! - that the planet is warming, that it's caused by human activity, and that areas of frozen water are giving up the ice. And they attempt to come off like supercilious know-it-alls fomenting their delusions and lies. Of course, they can't handle the truth.

http://prn.fm/cli...herever/


Boy, talk about a 'TROLL'...


May 21, 2019
I remember Al Gore telling us Miami would be underwater by 2015, in fact he stated most of Florida would be submerged by now as well as a large portion of Texas.

May 21, 2019
Answer my challenge: how can a speculation with a 5% to 95% probability not be useless?

I think you're thinking about this entirely wrong. The point in projections like these are to help with planning. When planning, you never look at the most likely case - you need to look at the worst case scenario. Think of any elevator you've gone into. It's rated for some weight. Will it fail if 1lb more is put in the elevator? No. That's because it's designed for to hold more weight than it's rated for (generally twice as much). The engineer took into account the range that cables, motors, etc. are rated for and used the worst cases.

It's similar for sea level rise and planning. If you're a politician or real estate developer and only assume the best case or most likely scenario, then you're incompetent (or a con artist).

May 21, 2019
Should you use the 2-meter projection? That depends on what you're planning. If you're planning a vacation in 5 years time, it probably doesn't matter. The risk/expense if you've failed is minimal even if the sea level rise in 5 years could make a difference to you. If you're planning a residential community, then you sure as hell should be looking at the worst case scenario. Also keep in mind that sea level rise won't magically stop in 2100. We're on the hook for several more meters, so if you're timeline is long enough you need to consider that as well.

Something else to consider is that actual sea level rise has historically come in at the very upper range of projections. Given a history like that, you'd be a complete idiot not to look at what the upper range of projections is.

May 21, 2019
Won't bother me in my lifetime, I'm 30 meters above mean sea level. Those people who live downhill, not so sure about. Fodder for the sewage rope gangs. I'd sure go hang someone who denied and lied by their heels to drown in the sewage.

May 21, 2019
zz5555

Okay. Well, there's a 100% probability that the next glaciation will descend on the earth within the next few thousand years. It is already overdue. It may already have begun.

Let's plan for 2 miles of ice over New York and Chicago.

May 21, 2019
zz5555

Okay. Well, there's a 100% probability that the next glaciation will descend on the earth within the next few thousand years. It is already overdue. It may already have begun.

Let's plan for 2 miles of ice over New York and Chicago.

Actually there's a 0% probability of that happening. The next glaciation wasn't due for a few thousand years. It's well known that humans have delayed the next ice age by tens of thousands of years due to the increase in greenhouse gases. And there would be fewer things we'd have to worry about in that timeline. Saying that ice may cover a location in 5000 years would make no difference in, say, planning a new residential community. I'm not sure of anything that you could plan that would have a timeline of thousands of years. Regardless, it makes no sense whatsoever to plan for an event thousands of years from now and ignore one that's only 80 years away.

May 21, 2019
The last interglacial (Eemian) was hotter than this one (Holocene.) It lasted about 15,000 years, and other interglacials were shorter than that. Some longer. Please link to the science that knows -- knows -- when the next glaciation would have been due, if humans had not evolved. That is the baseline.

Meanwhile, it is not proven to what extent mankind's release of carbon has delayed the next glaciation.

Even if it were absolutely true that AGW has delayed or ended [HA!] the ice cycles, I guarantee you will want your descendants to live in a warmer world, not a cold one.

May 21, 2019
Please link to the science that knows -- knows -- when the next glaciation would have been due, if humans had not evolved.

I'm not sure how that's relevant. The shortest I've seen is 1000 years from now, but I've also seen much longer. The mean of the estimates for the previous interglacial is ~17k years. We've only been in this one less than 12k years.
Meanwhile, it is not proven to what extent mankind's release of carbon has delayed the next glaciation.

As you know (or should know), science isn't about proof. I'm not sure what to suggest if you can't deal with that. However, there are a number of things that indicate that the mankind's release of carbon has delayed the next glaciation by a long time. First, models show this. I know that the anti-science groups hate models, but the fact is that models perform very well.

May 21, 2019
Second, we are in a weak glaciation cycle. Models show that no glaciation can occur with CO2 levels above 280. (By the way, this paper (https://people.cl...2012.pdf ) indicates that the next interglacial would start in ~1500 years if CO2 levels were below ~240. I'll accept that if that makes you happy.)

I also seem to recall that no glaciation has occurred (at present solar levels) with CO2 levels this high, but can't find the reference right now. Anyway, that's enough evidence that we've had a great affect on glaciations.

Even if it were absolutely true that AGW has delayed or ended [HA!] the ice cycles, I guarantee you will want your descendants to live in a warmer world, not a cold one.

I often see this level of crappy logic, but never understand why the people who make this claim don't think about what they're saying.

May 21, 2019
Yes, a warmer world would be better than an ice age. But that doesn't mean that the only choices are glaciation and +5C warmer. Even with a 1C increase we're seeing economic and environmental damage that we would be better without. Why not limit it to 0.5C increase over pre-industrial? It makes no sense whatsoever to claim that it's better to incur monumental damage to our economies and environment just so we can avoid a glaciation in a couple thousand years. It is not an either/or choice and your claiming it is does you no favors.

May 21, 2019
Okay, I'll pivot and put it back on you:

The benefits from a warmer earth, even at the end of this century, and for a few thousand years, will be substantially greater than the deficits of hotter climate. It will happen in slow motion over many centuries, the abundance of new farm land and sea routes, and many other benefits will be very great. No one will die because the rise of heat caught them from behind as they flee south.

Please don't tell me we are about to set off the full Venus event and roast the earth under a perpetual haze of CO2. That claim will do you no favors.

I will look into the link you posted later.

May 21, 2019
Me: Even if it were absolutely true that AGW has delayed or ended [HA!] the ice cycles, I guarantee you will want your descendants to live in a warmer world, not a cold one.

zz5555: [why don't you post with your real name?] "I often see this level of crappy logic, but never understand why the people who make this claim don't think about what they're saying."

We do think about it. My claim is correct and strong. It's the AGW activists who don't think about the benefits of a warmer world ... they only throw up dire (and ridiculous) scare "feasibilities."

May 21, 2019
Just to correct some of this, the Milankovic cycles dictate that the next ice age will not be for 35,000 to 50,000 years. This will override any minor atmospheric effects that can accumulate due to human activity. No matter what we do we cannot overcome the effects of reduced insolation for 10,000 some-odd years. The question is what will happen between now and then, and right now it looks like a catastrophe for billions of humans.

If you don't care, so be it but denying it isn't a solution.

May 21, 2019
fraud and fearmongering are NOT the way to promote policy change at a meaningful level, what fraud based fearmongering does is make the people who are dug in , on this issue, start aggressively attacking those promoting change for the better.

it is like a hard sell from a desperate salesman. people who see this are thrown away, even if they are not dug in against buying a used car, they will start to think it's a lemon anyways.
the so called global warmers who want more rapid action and change at the policy level are digging their own grave by doing this. they are losing trust. something that takes a lot longer to build than to destroy----ironically just like the climate....

May 21, 2019
The climate catastrophe at the end of the Permian killed off 90% of all life on Earth.

It got better. But huge swaths of species died out, and it took a long time for life to come back.

I don't doubt that life on Earth will survive. The question is whether humans will.

May 22, 2019
The ocean could rise by 2 meters, but it could easily go down by 2 meters. The warmer earth could cause more snow to fall on Greenland and or the south pole. What is clear is that CO2 will raise earth temperatures and make the climate more stable. It is clear from the records that low CO2 levels lead to rapid swings in earth temperatures and extreme ice-ages.

May 22, 2019
Da Schneib

I'm challenging this:
"the Milankovic cycles dictate that the next ice age will not be for 35,000 to 50,000 years. "

Where did you get that claim? Please link the science for that. I have seen mild advice in old textbooks that interglacials CAN last 35,000 to 50,000 years, so maybe that's where you are pulling that number. The prior interglacial lasted 15,000 years and we are 12,000-14,000 years into this one.

The next glaciation may have already begun. Even if slowed by AGW.

May 22, 2019
zz5555

Reading that paper, I pushed it aside after reading the abstract. For now. I'll look into it deeper if/when I have time.

Here is why it does not interest me.

1) it focuses on icebergs and CO2 as the driver of the ice cycles!
2) it begins talking about human-released CO2 immediately, thus it is focused on when the next glaciation 'might' occur given AGW.

This paper is interesting, but I still want to find science that gives a deeply justified and convincing date -- say, plus or minus 1,000 years -- when the next glaciation would get going if humans had not evolved.

May 22, 2019
On the other hand, none of the humans targeted by the sewage rope gangs will survive. That's a given.

May 22, 2019
It's how long the current interglacial is predicted to last based on the Milankovic cycles.

Let's start with this: https://science.s...585/1287

May 22, 2019
Betting you'll either disappear or start lying. Liar deniers always do.

May 22, 2019
Forty tornadoes and a hurricane before the official start of the hurricane season.

We done here?

May 22, 2019
Da Schneib

Betting you can't link supporting science not behind a paywall. This 2002 paper might be interesting. If it is a "killer argument" for a 50,000 year Holocene without mankind, then there would be hundreds of posts around discussing it.

Waiting ...

May 22, 2019
Da Schneib: "Forty tornadoes and a hurricane before the official start of the hurricane season. We done here?"

Well, you are!

1) arguing meta-climate-change based on a smidgen of recent weather is a sure sign of desperation and -- really, when you think about it -- an insult to thinking people;
2) what would stop me from hitting back with the embarrassing paucity of hurricanes over the last 15 years? [I won't do that, because I am not desperate.]

May 22, 2019
It is pretty much impossible to have a discussion about climate change unless one has access to the original unadjusted temperature data. Most of the graphs presented by NASA and NOAA today have had the data "adjusted" in order to show increased warming in the later years.

May 22, 2019
These Chicken Little scare tactics should be considered psychological terrorism.
https://www.brigh...76998001

May 22, 2019
CD85 the psychological terrorism starts in PreK and continues for 16 more years. No wonder drug use is out of control and suicide is a new highs among teens.

May 22, 2019
Forty tornadoes and a hurricane before the official start of the hurricane season.

We done here?

And 70 degrees in Phoenix for a high a week before June. What's your point, weather happens.


May 22, 2019
Da Schneib,

Per Berger:
Paleoclimatologists in 1972, invoking the last two interglacials of 10,000 yrs duration and no sign of warming definitively said "it is likely that the present-day warm epoch will terminate relatively soon if man does not intervene."

Berger then acknowledges that conclusion, but then lets loose with many mights, maybies, and coulds – not instilling much confidence in truth. Butler cites computer models and "stated" speculation by two others, and gives the reference in notes. I did not look into those. [continued next post]

May 22, 2019
Berger then spends the rest of the short paper in fascination with CO2 emitted by humans. So that is irrelevant to the issue of "when is the next interglacial due without man's emissions." Berger does not answer the question. Unless those two other studies pin down the due date of the next glaciation, Berger's paper is irrelevant, because floating a "might" for a 60,000 NotIncludingMan-Holocene when the last two were 10,000 years is an extraordinary claim.

I still have not seen a glimmer of certainty that Paleoclimatologists have a master grip on the engine of ice driven by sun cycles and earth permutation. It's rather horrifying that they don't, because they keep making powerful calls to change world behavior in a drastic way.

May 22, 2019
If you don't know anything about the Milankovic cycles you're just spouting politics. This is a science site. G'bye.

May 22, 2019
G'bye? Where are you going?
Wear your winter coat, it's cold outside.

May 22, 2019
I don't bother much with trolls, especially climate trolls. If you're going to deny science you're a liar denier and I know all about you people.

You lie a lot and you're vulnerable to being proven to be lying.

You're fun to play with, mousie.

May 22, 2019
Every so often I pick out a liar denier troll and torture them. It's fun to watch them squirm. You squirm most delightfully, liar denier.

You're denying geophysics dating back 40 years. So, were you born stupid, or did you have to practice?

Just askin'.

May 22, 2019
So let me ask now, why are you arguing about geophysics when you don't know any geophysics from the last half-century?

May 22, 2019
That you have to hurl insults, and throw the lamest internet trope ever invented, tells the world who is weak here.

May 22, 2019
It's not insults you're whining about. It's a century of Milankovic theory. He put his first paper out in 1920. The first confirmation that we would have an extended interglacial was put out in 1980, and the estimate at that time was 26,000 years. Nowadays we have better computers than in 1980 (maybe you didn't notice) and it's been extended to 50,000 years.

This has been known for a century. You're lying and denying, and trolling, just like I said.

Sorry, your "degree" from the university of Mommy doesn't work here, home "schooled" troll.

May 23, 2019
@JohnDonohue.
The benefits from a warmer earth, even at the end of this century, and for a few thousand years, will be substantially greater than the deficits of hotter climate.
It's the TRANSITION period to that warmer planet that is the immediate problem; as it causes (and already is causing) disastrous AGW-exacerbated extremes of storms/cyclones/hurricanes/droughts/floods/hail etc (as you can readily conform for yourself via news reports over last few decades).
It will happen in slow motion over many centuries, the abundance of new farm land and sea routes, and many other benefits will be very great.
Not so; you are forgetting the 'tipping point' which will unleash vastly greater previously long-naturally sequestered Methane/CO2 in land/ocean clathrates/hydrates and burning peatlands which will dry out and burn unstoppably (some already are). And more diseases/pests/unseasonal storms destroying health/infrastructure/agriculture etc. Rethinkit all, mate. :)

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