Study finds early warning signals of abrupt climate change

December 8, 2014
Credit: Tiago Fioreze / Wikipedia

A new study by researchers at the University of Exeter has found early warning signals of a reorganisation of the Atlantic oceans' circulation which could have a profound impact on the global climate system.

The research, published today in the journal Nature Communications, used a simulation from a highly complex model to analyse the Atlantic Meridional Overturning Circulation (AMOC), an important component of the Earth's climate system.

It showed that signals are present up to 250 years before it collapses, suggesting that scientists could monitor the real world overturning circulation for the same signals.

The AMOC is like a conveyor belt in the ocean, driven by the salinity and temperature of the water. The system transports heat energy from the tropics and Southern Hemisphere to the North Atlantic, where it is transferred to the atmosphere.

Experiments suggest that if the AMOC is 'switched off' by extra freshwater entering the North Atlantic, surface air temperature in the North Atlantic region would cool by around 1-3°C, with enhanced cooling of up to 8°C in the worst affected regions.

The collapse would also encourage drought in the Sahel - the area just south of the Sahara desert - and dynamic changes in sea level of up to 80cm along the coasts of Europe and North America.

"We found that natural fluctuations in the circulation were getting longer-lived as the collapse was approached, a phenomenon known as critical slowing down," said lead author Chris Boulton.

"We don't know how close we are to a collapse of the circulation, but a real world early warning could help us prevent it, or at least prepare for the consequences" adds co-author Professor Tim Lenton.

The study is the most realistic simulation of the climate system in which this type of early warning signal has been tested.

"The best early warning signals in the model world are in places where major efforts are going into monitoring the circulation in the - so these efforts could have unexpected added value' adds Professor Lenton.

Explore further: Agulhas Current leakage could stabilize Atlantic overturning circulation

More information: 'Early warning signals of Atlantic Meridional Overturning Circulation collapse in a fully coupled climate model' by Chris Boulton, Lesley Allison and Timothy Lenton is published today in the journal Nature Communications.

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Anonym
2 / 5 (27) Dec 08, 2014
Presumably the "extra fresh water" that triggers the "collapse" comes from melting ice. AGW! Then the climate turns much colder, ice reforms, problem solved. So why the apocalyptic overtones in this article? Particularly as the authors concede they have no idea when the cycle ends. The suggestion that we can "do something" about the AMOC sounds ludicrous, but I guess if we can "do something" about "Climate Change"(TM), then surely we can control the AMOC, too.

When did the goal of Science, and science writing, become simple fear-mongering?
travisr
4.1 / 5 (23) Dec 08, 2014
We don't know what this will actually do to our environment. The risks range from food shortages to systemic food system failure for the human race. Rather then erring on the side of caution hoping more information comes out about this so we can predict the future, you are saying we should wing it?

99% of scientific literature supports global warming, and these scientists come from all parts of the world. On top of that there are real things like work ethic, integrity, honor, and honesty which should rule over some portion of climate scientists. Even if you don't believe in those, its laughable to think someone would spend 20 years in education to make 60k-100k a year by fabricating an elaborate story collusively with tens of thousands of other professors.

The real truth to all this is that most professors make their money TEACHING. They do research because its what they love.
Steve 200mph Cruiz
4 / 5 (24) Dec 08, 2014
@Anonym

Talking about the consequences of our actions on the climate isn't fear mongering. All they are doing is telling us what is happening, I've actually seen some occasional articles on things that global warming will benefit, but for 95% percent of life, a drastic change in climate is a bad thing.

When you go to a zoo and they tell you Orangutans are threatened by habitat loss, it's not fear mongering, it's a fact that they are effected by habitat loss.

If you find it scary that's a little thing called your conscious, I suggest you listen to it.
jscroft
1.6 / 5 (19) Dec 08, 2014
Awesome. Let's spend some MONEY!
Modernmystic
2.8 / 5 (10) Dec 08, 2014
but for 95% percent of life, a drastic change in climate is a bad thing.


95% is an exaggeration. It also depends on how you define "bad". The whole concept of "good" and "bad" is a human invention. So when you say it will be a bad thing, you're really saying something about what you value and nothing at all about the biosphere.

I happen to agree that an abrupt change will be incredibly destabilizing for human civilization, and will be accompanied by changes to the biosphere...AND we should do everything we can to avoid it. It would be far worse, however, if we were talking about another ice age instead of a warm period.

http://en.wikiped...mum#Life
jackjump
1.8 / 5 (20) Dec 08, 2014
Sounds like as good of an explanation as any for what launched the Little Ice Age from which we've been recovering for the last 200 years but it can hardly be blamed on man made CO2 since the same thing has happened at least three times during the current interglacial that's been going on now for ten thousand years or more and we've only been generating noticeable amounts of CO2 for the last 100 years or so:

http://www.atmos....oup4.htm

The article carefully avoids making the CO2 claim. It must be worrisome for the warmists though since it indicates we might be launching back into another Mini Ice Age which will be hard to explain after all the trumpeting of an approaching Thermageddon.
Bob_Wallace
4.1 / 5 (13) Dec 08, 2014
"Presumably the "extra fresh water" that triggers the "collapse" comes from melting ice. AGW! Then the climate turns much colder, ice reforms, problem solved"

Only the 'local' climate temperatures change. These changes in circulation patterns would not have an impact on the amount of heat we are now trapping inside our atmosphere.

All that would happen is a redistribution of heat.
Ozmandias
4.6 / 5 (12) Dec 08, 2014
If the thermohaline circulation slows down due to stratification as the authors suggest may indeed happen, any decrease in temperature at higher latitudes will not provide the impetus for increased ice formation. Equatorial water will become warmer as less heat is moved from it, and the atmospheric circulation cells will continue to transport heat polewards to offset the cooling. In fact, more extreme weather would be most likely as the horizontal pressure gradient between low and high latitudes increases. A warmer ITCZ would mean greater convection and lower pressure, leading to intensified Hadley circulation. Hurricanes would also be more frequent.
gkam
2.6 / 5 (15) Dec 08, 2014
"95% is an exaggeration. It also depends on how you define "bad". The whole concept of "good" and "bad" is a human invention."
-----------------------------------------------

Weasel words? I expected better from you, MM.
Modernmystic
2.8 / 5 (9) Dec 08, 2014
"95% is an exaggeration. It also depends on how you define "bad". The whole concept of "good" and "bad" is a human invention."
-----------------------------------------------

Weasel words? I expected better from you, MM.


I think you ought to look up the meaning of weasel word. It's actually someone who puts forth his or her values on amoral natural systems by using words like "good" or "bad" who's using an argument that can be later retracted, rephrased, and redefined endlessly. I'm stating that, as far as amoral natural systems go, there is no "good" or "bad"....that's people injecting morals into the mix. That's fine as long as they're not pretending it's anything more than an opinion.
gkam
2.7 / 5 (12) Dec 08, 2014
I think you used it in the context of the environment. Changes to the one in which we evolved could be catastrophic. We are part of the Community of Life on Earth, and any environmental changes affects all of it.
Modernmystic
1.6 / 5 (7) Dec 08, 2014
I think you used it in the context of the environment.


I was pointing out that the poster was giving us an example of his value set rather than a factual statement about the environment...in exactly the same way a creationist is giving us an example of his value set when he says the world is 5000 years old rather than a factual statement about history.

Now I'll give you an example of using weasle words....

Changes to the one in which we evolved could be catastrophic.


It could be yeah.....so what.

I don't disagree with your point, but if you want an example of what you accused me of you couldn't have provided a better one.

We are part of the Community of Life on Earth, and any environmental changes affects all of it.


A statement of the obvious neither conveys an argument, point, or even an opinion passed off as a fact...
gkam
2.3 / 5 (12) Dec 08, 2014
Perhaps you do not understand the implications, . . the possible consequences?
Modernmystic
1.8 / 5 (10) Dec 08, 2014
Perhaps you do not understand the implications, . . the possible consequences?


It's irrelevant to the point. We can talk about our values and opinions all day long. The biosphere doesn't hear them or care.

Now if someone shares their PERSONAL value set with me, I'm happy to give my opinion and have that DISCUSSION. What I'm not interested in is debating whether or not "the environment" is "good" or "bad" any more than I want to discuss how many angles can dance on a the head of a pin with a Jehovah's witness on my door step...
gkam
2.5 / 5 (11) Dec 08, 2014
"It's irrelevant to the point. We can talk about our values and opinions all day long."
--------------------------------------------

It has to do with the changing food growing areas, the lack of water for a billion people who are now fed by receding glaciers, the tropical diseases now in Alaskan birds, the spread of tropical insects.

Are these not included in your "values"??
Modernmystic
1.7 / 5 (6) Dec 08, 2014
It has to do with the changing food growing areas, the lack of water for a billion people who are now fed by receding glaciers, the tropical diseases now in Alaskan birds, the spread of tropical insects.

Are these not included in your "values"??


Indeed they are, but we weren't talking about my values. We were talking about the environment. They are SEPARATE issues.

Why are you so pissed? I'm just stating the obvious.

It's in my value set to do something about global warming. I think it's a very important issue. I don't pretend that my opinions are facts though.
gkam
2.2 / 5 (10) Dec 08, 2014
"Indeed they are, but we weren't talking about my values. We were talking about the environment. They are SEPARATE issues."
------------------------------------

My point exactly. You used the word "values" not me.

Please stop the semantic silliness. We have to do something other than our present course. Do you agree?
Modernmystic
1.8 / 5 (5) Dec 08, 2014
My point exactly. You used the word "values" not me.


No you didn't use the word you just used the concept...

It has to do with the changing food growing areas, the lack of water for a billion people who are now fed by receding glaciers, the tropical diseases now in Alaskan birds, the spread of tropical insects.


And then tried to weasel out of it by saying you didn't use the WORD, which is my entire point.

Please stop the semantic silliness.


Would you stop the semantic "silliness" if it was a creationist passing off his opinion as a fact? I don't think so.

We have to do something other than our present course. Do you agree?


Yes, I agree. It's not me you have to convince though, and you're not going to convince anyone using emotional appeals to values. THAT'S my point.
Scroofinator
1 / 5 (2) Dec 08, 2014
Experiments suggest that if the AMOC is 'switched off' by extra freshwater entering the North Atlantic, surface air temperature in the North Atlantic region would cool by around 1-3°C, with enhanced cooling of up to 8°C in the worst affected regions.


Sounds like a good explanation for why we see evidence of a drastic cooldown period after the interglacials.

http://www.climat...20BP.gif

Perhaps the AMOC is the driver between glacial/interglacial periods.
runrig
4.3 / 5 (8) Dec 09, 2014
Experiments suggest that if the AMOC is 'switched off' by extra freshwater entering the North Atlantic, surface air temperature in the North Atlantic region would cool by around 1-3°C, with enhanced cooling of up to 8°C in the worst affected regions.


Sounds like a good explanation for why we see evidence of a drastic cooldown period after the interglacials.

http://www.climat...20BP.gif

Perhaps the AMOC is the driver between glacial/interglacial periods.


http://en.wikiped...er_Dryas
Scroofinator
not rated yet Dec 09, 2014
Not quite sure what you are trying to say rig, but the YD was the effect, not the cause. Even the YD description from wiki tends to agree with this article:

But cooling in the tropical North Atlantic may have preceded this by a few hundred years
runrig
4.5 / 5 (8) Dec 09, 2014
Not quite sure what you are trying to say rig, but the YD was the effect, not the cause. Even the YD description from wiki tends to agree with this article:

But cooling in the tropical North Atlantic may have preceded this by a few hundred years

Just that the disruption of the AMOC can stopped by adding fresh water to the N Atlantic. And that the YD was an example of it.
Scroofinator
not rated yet Dec 09, 2014
And that the YD was an example of it.

Ok, then we are on the same page. Wasn't sure if that's what you were trying to say or not.

If the AMOC is "off", does that mean the circulation patterns stop or that there is simply a restructuring period of oceanic currents? I find it hard to believe that the ocean will just become 'stagnant'.
Floyd_Howard_Jr_
1.8 / 5 (10) Dec 09, 2014
No,No,No,...........the warning signs happened during the last Ice Age!!!!!!!!!!!!!
RWT
1.8 / 5 (10) Dec 09, 2014
How do they propose we "do something about it?" What a ludicrous thought.

How much "extra" fresh water enters the current from year to year? The difference from year to year is minimal but that's what is important here, however, as fresh water enters the north Atlantic every summer. What happened ca. 12,000 years ago when over an order of magnitude more fresh water was entering the North Atlantic every summer? Is there evidence for the slowdown of the AMOC during previous interglacial periods when the Earth was at least 2 degrees warmer and sea level was several meters higher? I was hoping to see a study based on actual data, not another computer science circle jerk.
psychosalmon
1.6 / 5 (13) Dec 09, 2014
Greenland's ice mass has increased by over two deviations above normal according to DMI so far this year. This is proof to climate lunatics that Greenland is melting.

This story is a hedge. When it get's colder, which NCEP says it is, they can blame it on Warming, just like they blame cold in Europe, US, sea ice in Antarctica, droughts, floods... It is so predictable at this point.
runrig
4.3 / 5 (12) Dec 09, 2014
Greenland's ice mass has increased by over two deviations above normal according to DMI so far this year. This is proof to climate lunatics that Greenland is melting......


It's called weather my friend.
Comprehension helps.......
"Note that the accumulated curve does not end at 0 at the end of the year. Over the year, it snows more than it melts, but calving of icebergs also adds to the total mass budget of the ice sheet. Satellite observations over the last decade show that the ice sheet is not in balance. The calving loss is greater than the gain from surface mass balance, and Greenland is losing mass at about 200 Gt/yr."
artist1270
1.5 / 5 (13) Dec 09, 2014
In order for this to be true, the polar caps would have to be melting. And since they're not, maybeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee shut the f-#! up? Thanks.
gkam
3 / 5 (14) Dec 09, 2014
"maybeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee shut the f-#! up? Thanks."
-----------------------------------------

Perhaps you think you are posting on Free Republic?
runrig
4.3 / 5 (11) Dec 10, 2014
In order for this to be true, the polar caps would have to be melting. And since they're not, maybeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee shut the f-#! up? Thanks.


Err they are, and all the hand-waving, denial and shouting wont make it any the less true my friend. Go away. Thanks.
Scroofinator
3.7 / 5 (6) Dec 10, 2014
In order for this to be true, the polar caps would have to be melting.

They are shitbrick. Visual surface area is not equal to volume. Calving is the process of the the glacier melting from the bottom due to it's contact with the oceans.
http://www.nasa.g...NyCvF8uc
If you're gonna try to argue against AGW, at least know what you're talking about. You don't help the cause any by sounding like a toddler.
jdswallow
1.6 / 5 (7) Dec 11, 2014

It's called weather my friend.
Comprehension helps.......
"Note that the accumulated curve does not end at 0 at the end of the year. Over the year, it snows more than it melts, but calving of icebergs also adds to the total mass budget of the ice sheet. Satellite observations over the last decade show that the ice sheet is not in balance. The calving loss is greater than the gain from surface mass balance, and Greenland is losing mass at about 200 Gt/yr."


Tony Banton is up to his old tricks again, I see of trying lecture folks about things he knows nothing about.
Greenland ice sheet mass balance reconstruction. Part I: net snow accumulation (1600-2009)
Journal of Climate 2012 ; ''We find a 12% or 86 Gt y-1 increase in ice sheet accumulation rate from the end of the Little Ice Age in ~1840 to the last decade of the reconstruction. This 1840-1996 trend is 30% higher than that of 1600-2009, suggesting an accelerating accumulation rate.
jdswallow
1.6 / 5 (7) Dec 11, 2014
The correlation of Ât(G) with the average surface air temperature in the Northern Hemisphere (SATNHt) remains positive through time, while the correlation of Ât(G) with local near-surface air temperatures or North Atlantic sea surface temperatures is inconsistent, suggesting a hemispheric-scale climate connection. An annual sensitivity of Ât(G) to SATNHt of 6.8% K−1 or 51 Gt K−1 is found.
The reconstuction, Ât(G), correlates consistently highly with the North Atlantic Oscillation index. However, at the 11-yr time scale, the sign of this correlation flips four times in the 1870–2005 period.
http://journals.a...-00373.1

Again, why do you people lie so much and so often?
PetePassword
4.2 / 5 (5) Dec 11, 2014
Presumably the "extra fresh water" that triggers the "collapse" comes from melting ice. AGW! ... if we can "do something" about "Climate Change", then surely we can control the AMOC, too.
Why, what's your reasoning? Stopping our pollution is something we can do. Stopping freshwater melt into the ocean isn't. It's an effect of the former.
When did the goal of Science, and science writing, become simple fear-mongering?
Sums up precisely what motivates deniers, they simple can't take reality, it's too scary, so, heads between legs they describe the view ... unsurprisingly it's all shit.
runrig
4.4 / 5 (7) Dec 11, 2014

Tony Banton is up to his old tricks again, I see of trying lecture folks about things he knows nothing about.

Ah, splendid, mr swallow honours with a visit:
As I said "comprehension" my friend.
Merely posting up a relevant para from the article.
It is you that do the lecturing.
Based on a massive D-K syndrome.
Thanks for coming back BTW.... and goodbye - I've had enough of talking to idiots.
One of things you did achieve on here though was for Physorg to make it impossible to go over 1000 char (well done) ... and importantly give us the ability to ignore users.
Ever so pleased you did that.
TaTa
jdswallow
1.8 / 5 (5) Dec 11, 2014

Tony Banton is up to his old tricks again, I see of trying lecture folks about things he knows nothing about.


Tony Banton is up to his old tricks again. Not answering questions that are valid by saying such nonsense as
"Merely posting up a relevant para from the article." What is this article telling you when it said: ''We find a 12% or 86 Gt y-1 increase in ice sheet accumulation rate from the end of the Little Ice Age in ~1840 to the last decade of the reconstruction. This 1840-1996 trend is 30% higher than that of 1600-2009, suggesting an accelerating accumulation rate"? And you sputtered: "The calving loss is greater than the gain from surface mass balance, and Greenland is losing mass at about 200 Gt/yr."
Water_Prophet
2 / 5 (4) Dec 11, 2014
When did the goal of Science, and science writing, become simple fear-mongering?

That's what all news is about. Creating enough uncertainty in people so that you are afraid to act-because you MIGHT be wrong.

Go ahead and be wrong is my opinion. Certainly it hasn't stopped those on my ignore list, and the truth ignores them.
jdswallow
2 / 5 (4) Dec 12, 2014
"The interaction between water temperature and salinity effects density and density determines thermohaline circulation, or the global conveyor belt. The global conveyor belt is a global-scale circulation process that occurs over a century-long time scale. Water sinks in the North Atlantic, traveling south around Africa, rising in the Indian Ocean or further on in the Pacific, then returning toward the Atlantic on the surface only to sink again in the North Atlantic starting the cycle again."
http://science.na...r-cycle/
jdswallow
2 / 5 (4) Dec 12, 2014
This one makes a mockery out of folks like Tony Banton saying that the ocean ate the missing heat the last 18+ years & they also say it is becoming acidic, of all things.
"As water travels through the water cycle, some water will become part of The Global Conveyer Belt and can take up to 1,000 years to complete this global circuit. It represents in a simple way how ocean currents carry warm surface waters from the equator toward the poles and moderate global climate." [The Global Conveyer Belt has suddenly stopped for several speculated reason in the past and caused dramatic and rapid climate changes always to the cold side; therefore, warm is preferable to cold any day]
http://science.na...r-cycle/
FastEddy
5 / 5 (1) Dec 16, 2014
We don't know what this will actually do to our environment. The risks range from food shortages to systemic food system failure for the human race. ...


LOL. ... And the other risks? Like maybe improved crop yields and food surpluses?

Mmmmmm ... any signs yet that food is actually in short supply at the University of Exeter (home of the glutton's club and the HRM Wine Club ... http://gotcore.co...trition/ ... http://www.thegua...pagenews ).

Least we all forget: Never in history has raising taxes changed the weather.
FastEddy
5 / 5 (1) Dec 16, 2014
"Presumably the "extra fresh water" that triggers the "collapse" comes from melting ice. AGW! Then the climate turns much colder, ice reforms, problem solved" ... All that would happen is a redistribution of heat.


But not redistribution of poverty?

Never in history has raising taxes changed the weather.
Mike_Massen
2.6 / 5 (5) Dec 21, 2014
Elsewhere Water_Prophet claimed
They show everything you need to know about why CO2 doesn't work
That is ONLY from Sol to Earth, U miss SO MUCH !

WHY Water_Prophet do U REFUSE to look at absorption/re-radiation of Earth to Space ?

You seem to have a very serious reading/comprehension neglect bias problem !

Please FOCUS on these SIMPLE questions, do U accept:-

1. Your TSI graph ONLY shows Sol to Earth - largely Shortwave (SW) ?

2. Earth converts SW to Longwave radiation (LW) ?

3. Negligible SW is emitted to space ?

SIMPLE logic by way of SUBTRACTION re energy PROVES LW to space is CORE issue !
.
.
.
Water_Prophet, these is a VERY simple issue, WHY do U ignore it to look intellectually feeble ?

Please be GENUINE & smarter & not come across with some form of disability... :-(

I await the clarity of response a REAL Physical Chemist (PC) can actually muster to this link:-
http://phys.org/n...day.html
Mike_Massen
1 / 5 (2) Dec 25, 2014
Elsewhere Water_Prophet expounded by showing us example of Hypocrisy
The biggest problem is from pretenders or people with no education who spout their opinions out, which is fine, but then deny even when they do not know, and of course are uninterested in learning or even considering a fact that contradicts their opinion
Agree fully with your pattern.

Your opinion Water_Prophet that CO2 is not significant re TSI is correct, agree with U :-)

Those graduating as Physical Chemist (PC) of which Water_Prophet claims, should KNOW energy flows in 3D, so Y do U completely IGNORE Earth's emissions which any person with intelligence & Physics training easily determine it MUST be overwhelmingly Long Wave (LW) ie. Plain to "see" Short Wave (SW) from Earth is negligible !

Why do U ignore LW, where CO2's absorbance/re-radiation is the HIGHEST ?

Water_Prophet muttered
..having only a fork's understanding of how the food tastes
What does this even mean ?
Mike_Massen
1 / 5 (2) Dec 26, 2014
Elsewhere Water_Prophet claimed
How can you say I ignore longwave radiations?
By evidence U ignored long wave (LW) radiation re CO2's interference to space, U only saw TSI.

U write fossil fuel (FF) proportion of TSI, yet U IGNORE FACT Earth converts short wave (SW) to LW & CO2 interferes with emission to Space. Nobody is disagreeing FF adds heat & CO2. But, U, as a claimed Physical Chemist (PC) haven't acknowledged CO2's interference U even claimed "CO2 is a red herring", which is obviously completely WRONG !

Water_Prophet claimed
..1998 was a very hot year; Industry was booming and the Sun was at/near a max
Huh? U claim Sun TSI was at max ? Not according to this
http://www.skepti...asic.gif

Water_Prophet claimed to be a PC, yet doesn't write like one, does Water_Prophet accept:-

1. TSI mainly SW
2. Earth converts SW to LW
3. LW to space interfered by CO2

Simple issue Water_Prophet I asked before, WHY do u evade ?

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