Aarhus University Researchers Find Arctic Warmer, Ice-Free in Summertime 10,000 Years Ago!

From the NoTricksZone

By P Gosselin

Moving goalposts

Sediment samples show Arctic was warmer 10,000 years ago and was ice free in the summertime. Moreover, the researchers say “it’s uncertain” if Arctic sea ice will disappear in the summertime before 2063.

Image: NASA (public domain) 

The Aarhus University conducted a study that confirms sea ice disappeared from the Arctic during the summer months during the early Holocene – 10,000 years ago.

Researchers from Aarhus University, in collaboration with Stockholm University and the United States Geological Survey, analyzed samples from the previously inaccessible region north of Greenland. The sediment samples were collected from the seabed in the Lincoln Sea. They showed that the sea ice in this region melted away during summer months around 10,000 years ago.

The research team concluded that summer sea ice melted at a time when temperatures were higher than today.

“Climate models have suggested that summer sea ice in this region will melt in the coming decades, but it’s uncertain if it will happen in 20, 30, 40 years, or more. This project has demonstrated that we’re very close to this scenario, and that temperatures only have to increase a little before the ice will melt,” says Christof Pearce, Assistant Professor at the Department of Geoscience, Aarhus University.

Summer temperatures higher than today

The researchers have used data from the Early Holocene period to predict when the sea ice will melt today. During this time period, summer temperatures in the Arctic were higher than today. Although this was caused by natural climate variability opposed to the human-induced warming, it still is a natural laboratory for studying the fate of this region in the immediate future.

In Aarhus the marine samples have been analyzed in collaboration with Associate Professor Marianne Glasius and academic technical staff Mads Mørk Jensen from the Department of Chemistry. Among other things, they studied molecules from certain algae that are only produced when there is sea ice. The researchers can thereby determine when summer sea ice was present in the area.

When the sea ice in the Lincoln Sea begins to melt during the summer months, it can have major consequences for the climate. Where white ice reflects the rays of the sun, a dark sea will absorb more than ten times as much solar energy.

“The sea ice is a base for many ecosystems. The algae we examined are food for fish, fish are food for birds, etc. How will the marine ecosystems be affected globally if the sea ice disappears? We don’t know the answer yet,” says Henrieka Detlef, an assistant professor at the Department of Geoscience.

According to the researchers from Aarhus University, the study can be interpreted as bad news and good news for the climate. Henrieka Detlef also said that if temperatures remain stable or perhaps even fall, “the sea ice would return to the area.”

Alarmist authors

Despite the undisputed powerful natural factors and cycles at play in the Arctic, some researchers take a more alarmist or even hysterical view of what the future holds. For example, warning that greenhouse gas emissions are heating up the planet, Christof Pearce said, citing dubious model results: “The study is a wake-up call, because we know that it will happen. This news is not making the situation more depressing, just more urgent. We have to act now so we can change it.”

The research is published in the journal Communications Earth & Environment, and presented using an alarmist narrative. The study’s results indeed confirm natural factors were at play during the early Holocene, and thus readers need to keep in mind that these natural factors have not gone away. They continue to change and drive our climate today.

Henrieka Detlef et al, Seasonal sea-ice in the Arctic’s last ice area during the Early Holocene, Communications Earth & Environment (2023). DOI: 10.1038/s43247-023-00720-w

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Tom Halla
May 27, 2023 2:10 pm

But His Ultimate Holiness, Blessed Michael Mann demonstrated that “natural variation” is nothing but a denier myth. His Holy Hockey Stick smote the deniers, and settled the issue forever!!

Reply to  Tom Halla
May 27, 2023 2:59 pm

There is also more summer ice now than during the Egyption, Minoan, Roman and Medieval Warm Periods, as well as the Holocene Climate Optimum. Even with four rather than three CO2 molecules per 10,000 dry air molecules now as opposed to the late 19th century, after the Little Ice Age Cool Period, Arctic summer sea ice extent is still well within normal limits, indeed larger than the Holocene average.

Reply to  Milo
May 27, 2023 4:23 pm

Too much emissions from 100% horsepower chariots.

Rud Istvan
May 27, 2023 2:23 pm

I am not sure about the quality of this research. Algae forms on the underside of sea ice in the Arctic summer. That is well known—a melting iceberg will tip over to expose the formerly underwater algae.. Are they saying it falls off and sinks if the ice melts? Are they saying more summer algae forms if there is no summer sea ice? If so, where is the experimental quantitative algae control? How do they know their sediment core region is 10000 years old—most ocean sediment cores are dated to only a few hundred years, not a few thousand years. And Marcott 2013 diddled those few hundred years.

Reply to  Rud Istvan
May 27, 2023 2:56 pm

Their methodolgy is explained in their paper:


Joseph Zorzin
Reply to  Milo
May 27, 2023 5:15 pm

from that link:

According to climate models, the Lincoln Sea, bordering northern Greenland and Canada, will be the final stronghold of perennial Arctic sea-ice in a warming climate. However, recent observations of prolonged periods of open water raise concerns regarding its long-term stability. Modelling studies suggest a transition from perennial to seasonal sea-ice during the Early Holocene, a period of elevated global temperatures around 10,000 years ago.

Models mentioned twice in the first paragraph- enough for me.

Reply to  Joseph Zorzin
May 28, 2023 1:10 pm

…. final stronghold of perennial Arctic sea-ice in a warming climate.


To cherry pick, compare 2016 to today…. truly a statement of utter bu11sh1t….

Reply to  Rud Istvan
May 27, 2023 5:56 pm

Just how does an iceberg “tip over”? Given that the density of liquid seawater is about 10% greater than that of sea ice, 90% of the mass of any visible iceberg will be submerged. There is no known overturning moment exerted on an iceberg, including wind or waves, that could overturn an iceberg and flip it upside down.

It is possible that a small piece of skim ice could be overturned by a large wave – but such is not an iceberg.

Bryan A
Reply to  Duane
May 27, 2023 8:14 pm
Reply to  Duane
May 28, 2023 6:55 am

The part of the berg that is underwater melts faster than the part that is in the air.
Eventually the part that is sticking out in the air becomes too big to be supported by the part in the water, and it flips.

Bryan A
Reply to  MarkW
May 28, 2023 12:27 pm

Not only melt but sudden fracture and separation under water can immediately alter the center of mass causing a turn or flip

Reply to  Duane
May 28, 2023 12:28 pm

As the video provided by Bryan A demonstrates, your premises are flawed.

Reply to  Duane
May 29, 2023 10:41 am

“There is no known overturning moment exerted on an iceberg, including wind or waves, that could overturn an iceberg and flip it upside down.”

Wrong. The scientific principle of center-of-mass versus center-of-bouyancy instability of a floating iceberg is very well understood . . . it is just that you are totally unaware of it.

Reply to  Rud Istvan
May 28, 2023 12:59 pm

It’s interesting that there are layers of algal detritus on the sea floor representing long time periods, but concluding open ocean or sea ice above is the cause simply because we know there are different algae growth rates under ice versus open ocean….There is a reasonable possibility of being wrong due to currents, pack ice movement due to prevailing winds, undersea land slides, fertilization of algae by other processes such as volcanic dust, given an hour one can come up with more possibilities….

Paul Stevens
May 27, 2023 2:30 pm

So, the fact that natural variation is sufficient to melt sea ice in the Arctic and has demonstrably done so without CO2 emissions proves that “It’s Worse Than We Thought!”

Not because the earth has been through warmer periods, and the plants and animals survived, demonstrating that 1.5C is no big deal but because, obviously, if we get to 1.5C, natural warming will occur and the tundra will start to smoke.

Gotta hand it to these guys. There’s always another catastrophic twist to the story.

Richard Page
Reply to  Paul Stevens
May 27, 2023 4:24 pm

The average temperatures 10,000 years ago during the early Holocene were far higher than we are experiencing now or will experience again in this interglacial. I think it is ridiculous to conflate the 2 although (as you have pointed out) it does quash the alarmist extinction narratives when you consider how many species survived those temperatures. That natural variation can cover such a huge range puts the alarmist narrative firmly back into lunatic fringe territory, not as part of mainstream science.

Rud Istvan
May 27, 2023 2:43 pm

A separate thought about this paper. Suppose they are correct that the Arctic summer sea ice in that region north of Greenland disappeared 10000 years ago. So What?
Polar bears survived, all the Arctic seals and seabirds survived, all the Arctic fish survived. The Eskimos survived. There is NO evidentiary support for any future climate alarm whatsoever.

Reply to  Rud Istvan
May 27, 2023 2:53 pm

No Eskimos lived in that area 10 Ka. Their ancestors were still in Siberia.

Otherwise, good points.

Rud Istvan
Reply to  Milo
May 27, 2023 3:20 pm

Just checked. Yup. The first Amerinds crossed the Bering Straight from Siberia about 14800 ya. But they went south along the west coast (Clovis culture). The first Eskimos to arrive in eastern Arctic Canada and Greenland arrived about 3800 years ago. Archaeologically established. Learn something new every day.

Reply to  Rud Istvan
May 27, 2023 3:24 pm

Basically, paleo-Eskimos had to wait for the last of the ice sheets mostly to melt before they could exploit the high Arctic. No one knows when the first paleo-Siberians entered North America. It might have been well before 15 Ka.

Pre-Clovis immigration is pretty well established now, but was it 20, 30 or 40 Ka? Maybe just limited to eastern Beringia (western Alaska) to start.

Reply to  Rud Istvan
May 27, 2023 3:54 pm

Clovis people are connected to Europe due to similar points being found in caves in Spain/France. The people could have used their little animal skin canoes to follow the sun and the ice westward to reach N. America from Europe.

Reply to  antigtiff
May 27, 2023 4:03 pm

The Solutrean origin of Clovis has long been hypothesized. Evidence for it is thin, but not nonexistent. During the Last Glacial Maximum, time of the Solutrean culture, not only was sea level at its lowest, but there was more permanent shore-fast ice on both continental margins and in winter ice floes formed across the North Atlantic, as they now do in the Arctic Ocean. So navigation crossing by skin boat was not impossible, however unlikely.

Reply to  Milo
May 27, 2023 4:20 pm

The Clovis people are almost only known by their points which were very skillful works of almost art. The ice in the N. Atlantic was once roughly from Ireland over to Canada and the Clovis people could paddle during the day and sleep on the ice at night….catch some fish…kill some seals…burn a little seal fat to melt ice for fresh water…and keep tracking westward. Clovis disappeared with the Extinction event of the large mammals…Woolly Mammoth..Woolly Rhino…etc. DNA investigaions may help one day…is there any European DNA in some American Indians dating back to the times?

Joseph Zorzin
Reply to  Milo
May 27, 2023 5:20 pm

Are you the same Milo who has a YouTube channel on this very subject? If so, I watch it all the time.

Joseph Zorzin
Reply to  Rud Istvan
May 27, 2023 5:19 pm

Maybe but archaeology isn’t physics. Much of what they come up with is guesses- it’s a data poor science. There’s still a big debate about the first Amerinds and when they arrived.

Joseph Zorzin
Reply to  Milo
May 27, 2023 5:17 pm

Do you know that for sure?

Reply to  Milo
May 27, 2023 7:57 pm

The Bluefish caves in Northwest Yukon Territory have human presence radiocarbon dated to ~24,000 years ago. The culture probably wasn’t Eskimo as we know it but people were up there in the area of North America near the Beaufort Sea.

Joseph Zorzin
Reply to  Rud Istvan
May 27, 2023 5:16 pm

And the ecology of that region most certainly was far richer without the ice.

Lee Riffee
Reply to  Rud Istvan
May 27, 2023 9:02 pm

Yes. I don’t know how they figure that so much catastrophe is in the making for a rise in temperature that pales in comparison to those periods in the recent past. If warmunists are correct about our recent minimal warming driving all sorts of plants and animals to the edge of extinction (or into extinction), then why do we still have those same plants and animals?
Really, most of the species that have gone extinct in the past few thousand years are victims of other sorts of human activities. Like over hunting/harvesting, habitat loss, introduction of competing non-native species, destruction of foodstuffs of said creatures, etc.

Clearly animals have survived some pretty wild temperature swings during glaciation and interglacials, none of which had anything to do with human causes.

Bill Parsons
Reply to  Rud Istvan
May 27, 2023 9:02 pm

Right. And up til now I thought the alarm was about warming which was unprecedented. Now it’s the fact that it happened before that is the scary part – because that presages a repeat.

Oh, Death…

May 27, 2023 3:38 pm

a dark sea will absorb more than ten times as much solar energy.

Ever notice when the Arctic sea ice reaches its minimum extent? For those who haven’t, it is mid September. So the sun is quite low on the horizon but still plenty of heat boring into the ocean causing evaporation in late September.

So the atmospheric water reaches its maximum by some time in October as all the land north of 40N in the vicinity of the Arctic Ocean is rapidly cooling – what do you expect will happen?

If climate models were useful, they could replicate interglacial and glacial periods. If the modellers realised CO2 has nothing to do with current warming in the Northern Hemisphere, they would know that the current interglacial is terminating. Interglacials last for a single precession cycle of 23kyr. The Northern Hemisphere has cooled for the last 11kyr and is just beginning to warm again, which is increasing snowfall. All natural and simply a repeat of the last 4 cycles that last a number of precession cycles until there is enough glaciers calving into the ocean to reduce the water cycle to the point where melting overtakes snowfall again.

Reply to  RickWill
May 27, 2023 3:55 pm

MIS 11, the Hoxnian Interglacial, lasted about 50,000 years, from 424 to 374 Ka. It was the longest and warmest interglacial of at least the past 500 millennia. The Greenland Ice Sheet’s Southern Dome melted virtually completely.

Reply to  Milo
May 27, 2023 4:54 pm

Yes, the recovery from glaciation took one and a half precession cycles but the interglacial was only one precession cycle. The first precession cycle in the recovery was during a period of low orbital eccentricity. The next cycle had higher eccentricity causing more melting than a single cycle because the glaciation was already under way and the low eccentricity not enough to reverse the melting. Sea level did indeed reach around 15m above the present level.

The precession cycle dominates glaciation/interglacial but it also reflects obliquity and eccentricity.

Despite the northern oceans warming now, Greenland is still losing ice mass but is gaining elevation and permanent ice cover. More Arctic Ocean warming will accelerate the snowfall.

Bryan A
Reply to  RickWill
May 27, 2023 10:08 pm

This chart appears to show Solar activity overlaid on the
Temperature/Sea Level over a period of 450,000 years.
Problem is, while Glacial/Interglacial Temperature reconstructions do go back more than 800,000 years, the Solar Cycle Record starts in 1755 about 270 years ago and wouldn’t overlay 450,000 year temperature cycle.
(The solar cycle would appear as a slight thick dash at the zero end)

Reply to  Bryan A
May 28, 2023 5:16 pm

This chart appears to show Solar activity 

The chart “shows” the calculated solar intensity at the top of the atmosphere at 40N for June. The world “appears” is superfluous. The solar intensity is based on the reconstruction of Earth’s orbit which is well defined over millions of years. That and the solar constant is all that is needed to know the cyclic variation ToA sunlight

Joseph Zorzin
May 27, 2023 5:06 pm

ice- who needs it?

Bryan A
Reply to  Joseph Zorzin
May 27, 2023 10:09 pm

My tea does for sure

real bob boder
May 27, 2023 5:18 pm

Color me blue and shot me into the sky, who’da thunk it

Peta of Newark
May 27, 2023 5:56 pm

Sorry no, I’m not buying this:”Among other things, they studied molecules from certain algae that are only produced when there is sea ice.

What molecules, what is this stuff exactly and if it was a source of food (being sought after and eaten) – why is it left lying around on the ocean floor?

“certain algae”
We have got to be talking a very particular ‘certain’ Are you saying this stuff actually grows on the ice. Somehow I don;t envisage even the most slovenly & unkempt householder ever finding greenery growing in their home food-freezer

“only when there is sea ice”
In other words, we’re talking coincidence here, not causation or in other other words, where i/was this ‘certain algae’ produced and did the sea ice only affect how it is carried around by river flows and ocean currents?

“among other things”
Translate: You looked at other things, which you don’t tell us about so we can only conclude they didn’t back you up.

Thus: you confected a CockAndBull story about slime that had grown and come from somewhere else. This was (toxic) slime which only got there because of ice jams/dams and that grew in temporary puddles & lakes (probably 10’s & 100’s miles inland) caused by those dams & jams which only occurred when there was sea ice. NOT in the sea and NOT on the ice.

When those dams/jams burst, the stuff was washed out into the ocean, rotted and sank. Nobody actually really did eat it because it was toxic (due to ‘certain’ chemicals) = contrary to what you say.

This thing is a complete and fantastical fabrication.

Smart Rock
Reply to  Peta of Newark
May 27, 2023 7:10 pm

Hoy, Peta. If you want to find out what they actually did in the study, you click on the link just below the nice graphic of the Arctic. This takes you to the phys.org article, where you will find another link to the paper itself (hint: it starts with “doi”). Luckily, this one is open access. Go study what they did and then come back and rant away if you still want to. But don’t complain that a dumbed-down magazine article doesn’t give enough details.

I tried to read it, but I’m only a hard-rock geologist and I drifted off. Too many details, plus I don’t really care anyway. Sea ice comes and goes. Ho hum.

May 27, 2023 5:58 pm

The climate changes on its own, repeatedly, without the aid of SUVs, gas stoves, or farting cattle.

May 27, 2023 6:03 pm

It was all those SUVs!

Bryan A
Reply to  clawmute57
May 27, 2023 10:12 pm

Not SUVs… SUCs…Sport Utility Carts…They really Suc

May 28, 2023 7:09 am

a dark sea will absorb more than ten times as much solar energy.

That particular myth has been refuted time and time again.
At the sun angles found in the arctic, even in the summer, water reflects almost as much light as does ice. Indeed, once ice starts to get dirty from dust and soot, it can end up absorbing more light than water does.

Arctic waters are dark precisely because so little light energy penetrates the water.

Beyond that, ice is an insulator. Once the ice is removed, the heat in the oceans is able to easily escape into space.

Melting sea ice is a negative feedback, not a positive one.

May 28, 2023 8:58 am

The Arctic was ice free 10,000 ya and we survived! No climate crisis.

Reply to  fansome
May 28, 2023 12:44 pm

Survived?….We proliferated.

Reply to  DMacKenzie
May 28, 2023 4:08 pm

Thus crisis for ma planet.

May 28, 2023 4:09 pm

I have read that, due to precession of the axis and obliquity changes, summer insolation then is estimated to have been about 65 watts/sq. meter more than it is now. That seems likely to have had a noticeable impact upon summer Arctic ice.

With that much sunlight change in the far north, assuming no difference in total irradiance, could there have been little or no difference in global average warmth as calculated under the concept used today?

Aside from that major difference, there have been reports from the past few hundred years of large decreases in far north ice. If such variations were fairly short lived, would they be likely to show up in proxy measurements?

May 29, 2023 10:30 am

Paging Al Gore, paging Mr. Al Gore . . . paging Al Gore . . . please pick up the white telephone, there is an inconvenient truth waiting for you . . . paging Mr. Al Gore . . .

May 31, 2023 10:02 am

Are the models running backward ?

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