Claim: The climate changed rapidly alongside sea ice decline in the north


Research News


Researchers from the Niels Bohr Institute, University of Copenhagen have, in collaboration with Norwegian researchers in the ERC Synergy project, ICE2ICE, shown that abrupt climate change occurred as a result of widespread decrease of sea ice. This scientific breakthrough concludes a long-lasting debate on the mechanisms causing abrupt climate change during the glacial period. It also documents that the cause of the swiftness and extent of sudden climate change must be found in the oceans.

Scientific evidence for abrupt climate change in the past finally achieved

During the last glacial period, app. 10,000 – 110,000 years ago the northern hemisphere was covered in glacial ice and extensive sea ice, covering the Nordic seas. The cold glacial climate was interrupted by periods of fast warmup of up to 16.5 degrees Celsius over the Greenland ice sheet, the so called Dansgaard Oeschger events (D-O).

These rapid glacial climate fluctuations were discovered in the Greenland ice core drillings decades ago, but the cause of them have been hotly contested. D-O events are of particular significance today as the rate of warming seems to be very much like what can be observed in large parts of the Arctic nowadays. The new results show that the abrupt climate change in the past was closely linked to the quick and extensive decline in sea ice cover in the Nordic seas. Very important knowledge as sea ice is presently decreasing each year.

“Our, up until now, most extensive and detailed reconstruction of sea ice documents the importance of the rapid decrease of sea ice cover and the connected feedback mechanisms causing abrupt climate change”, says Henrik Sadatzki, first author of the study.

Sediment core and ice core data were combined in order to achieve the result

The Norwegian researchers investigated two sediment cores from the Norwegian sea and the Danish researchers investigated an ice core from East Greenland for changes in the sea ice cover. Both sediment and ice cores were meticulously dated and further linked to one another through several volcanic layers of ash (tephra) identified in both.

Past sea ice cover was reconstructed in the marine cores by observing the relation between specific organic molecules produced by algea living in sea ice and others by algea living in ice free waters. In the Renland ice core from East Greenland the researchers looked at the content of Bromin. This content is connected to newly formed sea ice, since Bromin contents increase when sea ice is formed. A robust chronology and sea ice information in both sediment cores and the ice core could be established and used to investigate the extent of the sea ice changes in the Nordic seas during the last glacial period.

“We have investigated how the sea ice cover changed during the last glacial period in both marine cores and ice cores. With the high resolution in our data sets we are able to see that the Nordic seas, during the rapid climate changes in the glacial period, change from being covered in ice all year round to having seasonal ice cover. This is knowledge we can apply in our improved understanding of how the sea ice decline we observe today may impact the climate in the Arctic”, says Helle Astrid Kjær, Associate professor at the Ice, Climate and Geophysics section at the Niels Bohr Institute.

Sea ice changes in the past show how the climate today can change abruptly

The data the group of researchers present shows that the Nordic seas were covered by extensive sea ice in cold periods, while warmer periods are characterized by reduced, seasonal sea ice, as well as rather open ice free oceans. “Our records show that the extensive decline in sea ice could have happened during a period of 250 years or less, simultaneously with a phase in which the water in the oceans to the north mixed with the Nordic sea, and that this situation led to sudden changes in atmospheric warming”, says Henrik Sadatzki.

As the Nordic seas changed abruptly from ice covered to open sea, the energy from the warmer ocean water was released to the cold atmosphere, leading to amplification of sudden warming of the climate. The result of the study documents that sea ice is a “tipping element” in the tightly coupled ocean-ice-climate system. This is particularly relevant today, as the still more open ocean to the north can lead to similar abrupt climate change.


From EurekAlert!

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December 6, 2020 6:08 pm

Perhaps there was a change in the sea ice because there was one of those frequent and unpredictable changes in the Climate.

Bryan A
Reply to  nicholas tesdorf
December 6, 2020 6:30 pm

Correlation doesn’t necessarily equal causation

Reply to  nicholas tesdorf
December 6, 2020 9:45 pm

I’ve seen no proof that their methodology could discern cause from effect, leading event from following event.

john harmsworth
Reply to  nicholas tesdorf
December 7, 2020 8:17 am

It’s not possible that a climatic change could happen that quickly to drive the melt of the Arctic Ocean without some other factor being in play. We are in an Ice Age. The cycles of this age are driven largely by orbital mechanics but we don’t understand exactly what the “tipping points” ( I hate that phrase) are between advancing and retreating glaciation. It shouldn’t surprise us that whatever relative state we are in, we oscillate in a substantial way around that state. That’s what is happening now. The Little Ice Age was a little colder. Now it’s a little warmer. We can call it the Little Warm Silly Panic Age.

December 6, 2020 6:13 pm

But how could you have such a decline in sea ice without man-made CO2. Everyone knows that’s the only thing that affects climate.

Bryan A
Reply to  Harves
December 6, 2020 6:33 pm

+16.5c increase in Greenland
From a low of ??? +16.5c to a high of ???

Med Bennett
Reply to  Bryan A
December 6, 2020 8:48 pm

GISP2 records indicate fluctuations from approximately -47°C to -30°C over decades to centuries.

December 6, 2020 6:23 pm

And this sea ice volatility eons ago was directly caused by Igg and Ogg burning mammoth manure and twigs and sending emissions into the air, just like burning coal, gas and gasoline does today.

Or maybe not . . .

(BTW, haven’t Arctic sea ice low points been well document in historical records – 1922, 1960-thing?)

Bryan A
Reply to  Mr.
December 6, 2020 6:38 pm

Actually it was from Igg and Ogg’s herds of Arouchs and the Methane they produced

Reply to  Bryan A
December 6, 2020 7:41 pm

They drove Fjord’s.

Bryan A
Reply to  Scissor
December 6, 2020 8:55 pm

With the optional stone wheels?

Bryan A
Reply to  Bryan A
December 7, 2020 9:44 am

And available in 2 or 4 horsepower

Reply to  Bryan A
December 7, 2020 1:00 pm

The economy size only needs one horsepower.

December 6, 2020 6:29 pm

When the average ice coverage dropped from >40% to the current 13%, the change in albedo will have an effect on the temperature. The current ice pack survived much warmer temperatures than we observe today, so there’s not a lot of head room left for average ice to decrease much more, after all, it comes right back in the winter and no amount of GHG warming will stop winter.

Consider that clouds reflect about the same as ice/snow (about 40% more than the surface itself), 2/3 of the planet is covered by clouds, the average non reflected solar input where the ice was is 300 W/m^2, reducing the average ice from 13% to 0% increases incident energy increases the solar input to 13% of the planet by about 300*.4*1/3 = 40 W/m^2.

Amortize these 40 W/m^2 over the rest of the planet results in an average of 5.2 W/m^2. Given that the doubling claim of CO2 is 3C which results in 16.5 W/m^2 more surface emissions from the 4 W/m^2 of equivalent forcing claimed to cause it. 12.5 W/m^2 must be replaced above and beyond the forcing and even of all the ice on the planet had melted, only 5.2 W/m^2 of this can be accounted for.

December 6, 2020 6:37 pm

“as the still more open ocean to the north can lead to similar abrupt climate change” Or perhaps there is open ocean to the north has already occurred because of past climate change. Still very weak on cause and effect.

December 6, 2020 6:43 pm

Haven’t our trolls been assuring us that until the advent of CO2, the climate never, ever changed abruptly.

Reply to  MarkW
December 6, 2020 7:25 pm

Once again you’ve beaten me to it. 🙂 They say the modern temperature increase must be human caused because it has been too rapid to be caused naturally.

Today, Earth is warming at a much faster rate than it warmed over the 7,000 years since the last ice age. link

Reply to  commieBob
December 6, 2020 7:44 pm

Never realized before how ignorant the National Academy of Sciences is on this topic.

Reply to  Scissor
December 6, 2020 9:53 pm

The problem isn’t one of ignorance but of circular thinking. The problem is starting with the implicit assumption that their desired conclusions are true.

Reply to  Scissor
December 6, 2020 10:06 pm

Yep, since the rise our of the last proper ice age to the Holocene Optimum.

It has mostly been COOLING !!

Reply to  commieBob
December 6, 2020 9:22 pm

There is no doubt that the current warming is human caused. Homogenisation does not occur without a human intent.

Reply to  commieBob
December 6, 2020 11:40 pm

Doggerland flooded at a rate that could be observed by humans – up to 1m per annum

Obviously, this was caused by man-made CO2

Reply to  commieBob
December 7, 2020 9:01 am

Thermometers were invented in 1714, and weren’t very accurate until glass compositions were modified about 1850. Before then it was impossible to tell if any given century warmed or cooled quickly, and our treemometers and pond-bottomometers also measure rainfall and wind effects in unknown proportions… too inaccurate to determine if the last century is unusual.

Alexy Scherbakoff
December 6, 2020 7:14 pm

At least they got it right. Warm water heated the atmosphere and not the other way around.

Reply to  Alexy Scherbakoff
December 7, 2020 12:49 am

Warm water from undersea vulcanism, is my guess.

December 6, 2020 7:48 pm

Meanwhile, alarmists twist and roll to cover up the fragilities behind the story of their non problem….

Keith Rowe
December 6, 2020 8:54 pm

D-O events are likely cause by a buildup of heat in the oceans and a stratification in the tropics. The conveyor is very slow as the caps are covered and no ocean moving into the arctic area. The heat builds up and the energy is released as the conveyor started up which pushes up warm water as the stratified water deep heat releases in the north causing massive release of icebergs and ice on land and D-O events. If there is enough heat like the deep minimum for a long time, the heat builds up enough energy to maintain the melting until only Greenland and Antarctic are left and some feedback mechanisms allow a longer interglacial. But the math will always go back to releasing more energy than incoming and the ice ages return. The very high wind speeds of the deep minimum is indicative of this energy difference from the tropics to the poles as it tries to balance.

Chris Hanley
December 6, 2020 9:41 pm

“… the rate of warming seems to be very much like what can be observed in large parts of the Arctic nowadays …”.
That depends on the accuracy and precision of the proxy data.
The rate of warming depends on the time interval selected as the IPCC unintentionally illustrated:

Mike Dubrasich
December 6, 2020 9:53 pm

I thought the debate was over, like 25 years ago. Now we find out it just concluded! Does Algore know about this?

And a new scienterrific meme: tipping element. Never heard that one before. A gosh darn tipping element is gonna fry the Planet. Here comes Thermageddon. Where oh where are the two mile thick continental ice sheets when you really need them? Is it just me or are Ice Age glacial stadial deep freeze snowball Earth conditions something everybody yearns for? Nostalgia for Deadly Ice must be as contagious as WuFlu.

I wish Denmark had two mile thick glaciers again, burying that lovely nation so deep in ice that nothing alive could survive there. Not for my sake, but for the sake of the Researchers from the Niels Bohr Institute, University of Copenhagen who have concluded the debate, finally. Bully for them. What a bummer their precious ice is melting, melting, melting like the Wicked Witch.

First the continental ice sheets melt, exposing the Polar Ocean, and then it gets warmer. That makes sense. Debate off! The dear sweet ice is gone and tip, tip, tip over we go. Warmer is coming, oh no! Better rocket to Mars before summer gets here and everybody has to wear shorts.

December 6, 2020 10:18 pm

How about a bit of geothermal heat – warming water heating the atmosphere.

Patrick MJD
Reply to  Chris
December 6, 2020 11:27 pm

It does not work that way.

/sarc off

Climate believer
December 6, 2020 11:32 pm

We have two poles, why do we never hear about Antarctica?
That continent has been riding high on all the averages you want for sea ice, 1981-2010 average, interquartile and interdecile ranges, and that’s since August!

Reply to  Climate believer
December 7, 2020 12:52 am

Does that Antarctic sea ice value include the iceberg 1/3 the size of Wales (400 million Olympic swimming pools) heading towards South Georgia at an alarming rate?

Climate believer
Reply to  Roger.
December 7, 2020 3:08 am

You mean A68a that calved in 2017? there has also been a recent much smaller calving they’ve called B49 I think.
A68a is a beast of a berg that’s a fact, currently just over 200km from South Georgia and oddly about the same shape and size. It’s following a fairly predictable route across the Weddlle Sea, as previously tracked icebergs have done since 1978, and a millennia before that, in what they call “iceberg alley”.

I hope it misses, or grounds out before it disrupts the wildlife. On the plus side these monoliths of ice are a source of considerable amounts of iron for the Southern Ocean, that increases Phytoplankton, and doubles the sinking of CO² in the vicinity of these icebergs compared to just open sea.


No I don’t believe the current 13,500,000 km², or there abouts, of sea ice extent includes the iceberg, but you knew that.

Reply to  Climate believer
December 7, 2020 10:01 am

B49, you sunk my battleship!

Stephen Skinner
December 7, 2020 12:15 am

“The data the group of researchers present shows that the Nordic seas were covered by extensive sea ice in cold periods, while warmer periods are characterized by reduced, seasonal sea ice, as well as rather open ice free oceans. ”
What qualifications are required to arrive at these conclusions?

“The result of the study documents that sea ice is a “tipping element” in the tightly coupled ocean-ice-climate system. ”
This statement is just a re-enforcement of previous assertions. Minimum ice is approx. 3 months after maximum sun and maximum ice is approx. 3 months after minimum sun which demonstrates that it’s still the Sun ‘what done it’ and there is huge temperature lag in the oceans.

December 7, 2020 12:36 am

Arctic sea ice: second lowest minimum in 2020, followed by a slow refreeze, with over 6 weeks of the ice being at lowest for date… ice is currently second lowest for date (after 2016: considerable gap to other years).

The satellite record goes back 41 years, but there is a detailed assembly of all evidence going back now to the 1860s showing we have second lowest ice now for over 160 years at least. (and the eemian is irrelevant, because the conditions then are not in play today).

Reply to  griff
December 7, 2020 5:50 am

Griff, taking a look at AR 1, the graphs for the mid 70’s appear to be within 10 percent or closer to the artic sea ice levels of today. Certainly falls within the error percentage given the technology and techniques of the time period. 1974 was particularly low…

Reply to  griff
December 7, 2020 6:07 am

How about posting a link to all the detailed assembly of evidence going back to the 1860’s? Or do we just take your word for it?

Reply to  rbabcock
December 7, 2020 8:37 am

You have to take the Griffter’s word for it.

john harmsworth
Reply to  griff
December 7, 2020 8:21 am

Griff, the second lowest something since you became aware of it isn’t actually important. There are so many things you aren’t aware of. They won’t suddenly become critical if you ever become aware.
Are you aware that every single attempt to create heaven on Earth via Socialism or Communism has failed miserably? Most attempts have caused much death and misery.

David Kamakaris
Reply to  griff
December 7, 2020 9:00 am

Good Grief! You sure ride a high horse! By whose authority do you claim that the Eemian is irrelevant?

But just for the sake of argument, let’s say the Eemian is irrelevant (It’s not). How much sea ice do you think was present during the mid-Holocene Optimum when spruce trees covered the Arctic Tundra where TODAY it is too cold for trees to grow because of the presence of permafrost. Or are you now going to say that mid-Holocene is also irrelevant?

You can’t ignore history just because it does not conform to your pre-conceived, erroneous conclusions, though no doubt you will continue to try.

Reply to  David Kamakaris
December 7, 2020 12:24 pm

“You can’t ignore history”

griff HAS to DENY CLIMATE CHANGE history if he wants to retain his manic panic about Arctic Sea ice.

griff is perfectly capable of IGNORING anything that doesn’t suit his brain-washed AGW cultist.

That is what WILFUL IGNORANCE is all about.

its griff’s modus operandi…

…. . its who he is.

Reply to  griff
December 7, 2020 10:03 am

“because the conditions then are not in play today”

Let me guess, any time CO2 wasn’t rapidly rising is irrelevant because CO2 changes everything.

Reply to  griff
December 7, 2020 12:09 pm

“second lowest minimum in 2020”


Over a piddlingly short period since the highest extent outside the Little Ice Age

You sound like a mindless Norwegian Blue , griff-fool

Going back to the end of the COLDEST PERIOD IN 10,000 years makes you look like a complete cherry-picking moron, griff.

Current extent is FAR HIGHER than for most of the last 10,000 years.

You know that, so why keep up the childish, petulant “wolf, wolf” nonsense.

Reply to  griff
December 7, 2020 12:19 pm

“(and the eemian is irrelevant”)

Eemian was 130,000 years ago

The first 8000 years of the Holocene were definitely relevant.

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And there was MUCH LESS sea ice than there is now.

Everyone KNOWS the Little Ice Age was the COLDEST PERIOD IN 10,000 years.

Of course it had an anomalously high sea ice extent….. an EXTREME HIGH.

Choosing it as a reference point is one of the stupidest mindless things a troll could do.

The Arctic has RECOVERED slightly from that anomalously high sea ice extent.

And the Arctic is rejoicing in not being bound up in worthless sea ice all year.

Not only is the land surface GREENING, but the seas are also springing BACK to life after being TOO COLD and frozen over for much of the last 500 or so years (coldest period of the Holocene)

The drop in sea ice slightly toward the pre-LIA levels has opened up the food supply for the nearly extinct Bowhead Whale, and they are returning to the waters around Svalbard.–whale-food-returns/1401824

The Blue Mussel is also making a return, having been absent for a few thousand years, apart from a brief stint during the MWP.

Many other species of whale are also returning now that the sea ice extent has dropped from the extreme highs of the LIA. Whales cannot swim on ice. !

Great thing is, that because of fossil fuels and plastics, they will no longer be hunted for whale blubber for lamps and for whale bone.

Hopefully the Arctic doesn’t re-freeze too much in the next AMO cycle, and these glorious creatures get a chance to survive and multiply.

I know you absolutely HATE the thought of a more normal (ie much lower than now) Arctic sea ice extent, ..

but WHY do you hate Arctic sea life so much that you think the Arctic should be frozen solid all year ?

December 7, 2020 1:25 am

No no they’ve got it all wrong-

“Detailed projections suggest traditional winter activities such as building snowmen could be lost if global greenhouse gas emissions are not reduced…….

According to the new Met Office analysis, increasing emissions could mean the average hottest day in Hayes, west London, could reach 40C (104F) by around 2017.

The Met Office analysis also suggests winter rain could increase by up to a third on average without steps to reduce global emissions, but this is less certain and rainfall could decrease instead.”

We can’t have WUWT spreading fake news about climate change now can we Griff et al? Those wot gets rewarded with the biggest compooter and a Beeb show knows best-

Peta of Newark
Reply to  observa
December 7, 2020 2:20 am

And the BBC is laying it on thick:

There’s even a picture of Kerry cuddling a kid and signing something in there somewhere.

What I don’t get, from this last week’s weather is how the BBC can report ‘Severe Weather Warnings’, issued from the Met Office, concerning ice, sleet and snow.

OK fine. Snow & ice can be a real hazard in many activities

BUT THEN, we get stories like the above issuing a WARNING that snow and ice will become rare in the next 20 years

Is that not = Gaslighting?

Don’t whatever you do mention that in the comments section if they open one.
You WILL be cancelled.

Or maybe Boris will send Carrie round to pull your plonker. She seems to be an expert at that- Pulling Plonkers

Boff Doff
December 7, 2020 2:43 am

Excuse me everyone! Did you not read the article? There is no need for comment. Viz:
“This scientific breakthrough concludes a long-lasting debate on the mechanisms causing abrupt climate change during the glacial period”
So there you are.

Rich Davis
December 7, 2020 3:54 am

These D-O events from the distant past are apparently real as supported by proxy evidence. They are also manifestly all-natural events.

The natural warming events occurred with essentially zero anthropogenic CO2 emissions. Warming of up to 16.5 K. (Yup that’s a very similar warming to the 1 degree since the end of the Little Ice Age. Only about an order of magnitude higher).

Only the ideologically blinkered could view this as evidence that modern warming can only be due to human influence. Paging griff…

December 7, 2020 4:33 am

Debate, shmate! I’m only interested in HOW LONG THOSE COLD AND WARM PERIODS LASTED!!!

The LENGTH of time is much more important than what caused the changes, whether they were Sudden Switches or Long, Slow Plonks Downward. I do not give a flying frack in space what the temperature was or when it happened, only How Long Each Lasted.

Now when that gets sorted out, someone please let me know. Thanks.

Oh, almost forgot: why is this important?

Well, that’s very simple: we might well be heading to The End of This Warm Period, kids. Change of cycle, that sort of thing. If we have a “warm” winter, it lowers my utility bills. If it’s rotten cold and sloppy wet slush, it raises them, and annoys me. And then the birds show up on my front steps looking for food and I have to feed them, and every confounded pregnant squirrel in the neighborhood wants in on it.

So I ask again: How LONG did each of those cold & warmish cycles last?

Or am I the only living person who remembers the winter of 2010-2011, when northbound Lake Shore Drive was snowed in and blocked, thanks to a broken down bus? And there were people whose cars got stuck and buried in snowbanks, who froze to death in their cars that February 2011. And what about those later winters with prolonged periods of deep snows that hit the USA from Indiana eastward to Boston and buried peoples’ houses??? Am I the only person taking these things into account? Seems like the 2011 cycle mirrors the 1878 blizzard that went from the western states right through Chicago and upper Midwest and slammed into New York City.

Am I the only person taking a long, hard look at those events? They seem to come and go in cycles. This winter is turning out to be as mild and user-friendly as last winter and the winter before that. Haven’t had a real lasting snow here in about 6 years now. It all seems to be hanging out up north. Glad I had the furnace/AC replaced in November.

So AM I the only person noticing these things?

Bryan A
Reply to  Sara
December 7, 2020 9:49 am

Saras simply aren’t going to know what Snow is

Reply to  Sara
December 7, 2020 11:24 am

Yabbut it fetched up on my front steps this morning, right around the time the squirrel showed up and stole an apple off the porch railing. Life is never boring in my kingdom. 🙂

December 7, 2020 8:39 am

Sea ice changes in the past show how the climate today can change abruptly

Does that mean it’s NOT different this time? Or is it still different this time?

Bryan A
Reply to  TonyG
December 7, 2020 9:50 am

It’s different this time
They have a Boogie Man to blame (CO2)

David Coad
December 7, 2020 4:51 pm

Sudden Stratospheric Warming SSW is a well known natural event. Warming up to 50 Deg C on a massive scale. People don’t even blink an eye yet these are natural climate drivers. Oceans could produce a similar event. Volcanism is another obvious conclusion.

December 7, 2020 5:36 pm

“Even if greenhouse gases like carbon dioxide and water vapor are pumped into the early Martian atmosphere in computer simulations, climate models still struggle to support a long-term warm and wet Mars,”

“The faint young Sun paradox is the contradiction between the presence of liquid water in the early Solar System, and the faintness of the Sun. According to our understanding of stellar evolution, in the billion or so years after its formation 4.6 billion years ago, the Sun’s heat and light would only have been about 70 percent of its current output.”

So old Sol is warmer nowadays than it was and you need CO2 and water vapor to support life eh? Doomed I tell ya. We’re all doomed!
Doomed to be run by a bunch of hysterical over-emotional child Gretaheads.

Clyde Spencer
December 7, 2020 5:45 pm

“… abrupt climate change occurred as a result of widespread decrease of sea ice. ”

Right after the little boy asked why the king was wearing no clothes, he asked why there would be a widespread decrease of sea ice.

December 7, 2020 7:07 pm

These O-D warming events were during major glaciation (ice age). The warming events were major. We are not in an ice age so warming event is minor. Findings are largely irrelevant today except to point to the extreme importance of sea surface temperature changes due to currents in producing warming and cooling events. More work is needed to better understand ocean currents at all depths and related temperatures, Can large amounts of cold water come to the surface in long term cycles (thousands of years and longer) causing major cooling? At present only very short term cycles have been discovered.

Ulric Lyons
December 8, 2020 8:54 am

“The result of the study documents that sea ice is a “tipping element” in the tightly coupled ocean-ice-climate system. This is particularly relevant today, as the still more open ocean to the north can lead to similar abrupt climate change.”

Like trying to open a door which is already open. The only way for it to tip while it is warmer, is colder. During an interglacial period, the Arctic is normally warmer during each centennial solar minimum, which cancels their imaginary warming extra-tipping point.

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