Antarctica wasn’t quite as cold during the last ice age as previously thought

OREGON STATE UNIVERSITY

Research News

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IMAGE: ICE CORE RESEARCHER DON VOIGT EXAMINES AN ICE CORE AT THE WEST ANTARCTIC ICE SHEET DIVIDE (WAIS DIVIDE) PROJECT. view more CREDIT: PHOTOGRAPH BY GIFFORD WONG

CORVALLIS, Ore. – A study of two methods for reconstructing ancient temperatures has given climate researchers a better understanding of just how cold it was in Antarctica during the last ice age around 20,000 years ago.

Antarctica, the coldest place on Earth today, was even colder during the last ice age. For decades, the leading science suggested ice age temperatures in Antarctica were on average about 9 degrees Celsius cooler than at present.

An international team of scientists, led by Oregon State University’s Christo Buizert, has found that while parts of Antarctica were as cold as 10 degrees below current temperatures, temperatures over central East Antarctica were only 4 to 5 degrees cooler, about half of the previous estimates.

The findings were published this week in Science.

“This is the first conclusive and consistent answer we have for all of Antarctica,” said Buizert, an Oregon State University climate change specialist. “The surprising finding is that the amount of cooling is very different depending on where you are in Antarctica. This pattern of cooling is likely due to changes in the ice sheet elevation that happened between the ice age and today.”

Understanding the planet’s temperature during the last ice age is critical to understanding the transition from a cold to a warm climate and to modeling what might occur as the planet warms as a result of climate change today, said Ed Brook, a paleoclimatologist at OSU and one of the paper’s co-authors.

“Antarctica is particularly important in the climate system,” Brook said. “We use climate models to predict the future, and those climate models have to get all kinds of things correct. One way to test these models is to make sure we get the past right.”

The study’s co-authors are an international team of researchers from the United States, Japan, the United Kingdom, France, Switzerland, Denmark Italy, Korea and Russia. The study was supported in part by the National Science Foundation.

“The international collaboration was critical to answering this question because it involved so many different measurements and methods from ice cores all across Antarctica,” said co-author T.J. Fudge, an assistant professor in Earth and Space Sciences at the University of Washington. “Ice cores that were recently drilled with support from the National Science Foundation allowed us to gain new insights from previously drilled cores, as well.”

The last ice age represents a natural experiment for understanding the planet’s sensitivity to changes in greenhouse gases such as carbon dioxide, the researchers said. Core samples taken from ice that has built up over hundreds of thousands of years helps tell that story.

Researchers in the past have used water isotopes contained in the layers of ice, which essentially act like a thermometer, to reconstruct temperatures from the last ice age. In Greenland, those isotope changes can be calibrated against other methods to ensure their accuracy. But for most of Antarctica, researchers have not been able to calibrate the water isotope thermometer against other methods.

“It is as if we had a thermometer, but we could not read the scale,” said Buizert, an assistant professor in OSU’s College of Earth, Ocean, and Atmospheric Sciences. “One of the places where we had no calibration is East Antarctica, where the oldest continuous records of ice cores have been drilled, making it a critical location for understanding climate history.”

In the new study, the researchers used two methods for reconstructing ancient temperatures, using ice cores from seven locations across Antarctica – five from East Antarctica and two from West Antarctica.

The borehole thermometry method measures temperatures throughout the thickness of an ice sheet. The Antarctic ice sheet is so thick that it keeps a memory of earlier, colder ice age temperatures that can be measured and reconstructed, said Fudge, an assistant professor in the department of earth and space science at the University of Washington.

The second method examines the properties of the snowpack as it builds up and transforms into ice over time. In East Antarctica, that snowpack can range from 50 to 120 meters thick and has compacted over thousands of years in a process that is very sensitive to temperature changes.

The researchers found that both methods produced similar temperature reconstructions, giving them confidence in the results.

They also found that the amount of ice age cooling is related to the shape of the ice sheet. During the last ice age, some part of the Antarctic ice sheet became thinner as the amount of snowfall declined, Buizert said. That lowers the surface elevation and cooling in those areas was 4 to 5 degrees. In places where the ice sheet was much thicker during the ice age, temperatures cooled by more than 10 degrees.

“This relationship between elevation and temperature is well-known to mountaineers and pilots – the higher you go, the colder it gets,” Buizert said.

The findings are important for improving future climate modeling but they do not change researchers’ perception of the how sensitive the Earth is to carbon dioxide, the primary greenhouse gas produced through human activity, he said.

“This paper is consistent with the leading theories about sensitivity,” Buizert said. “We are the same amount of worried today about climate change as we were yesterday.”

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noaaprogrammer
June 5, 2021 10:22 pm

“Antarctica wasn’t quite as cold during the last ice age as previously thought.”
 
These “findings are important for improving future climate modeling but they do not change researchers’ perception of the how sensitive the Earth is to carbon dioxide, the primary greenhouse gas produced through human activity, he [Buziert] said.”
 
So evidently the models have to be re-tuned, but Buizert wants to let us know that the modelers still know “how sensitive the Earth is to carbon dioxide, the primary greenhouse gas produced through human activity.”
 
I would like to know more precisely why he felt compelled to say that.

mikebartnz
Reply to  noaaprogrammer
June 5, 2021 10:59 pm

He basically says you can ignore their research

Jimmy Joe Meeker
Reply to  noaaprogrammer
June 5, 2021 11:02 pm

Because it is necessary to say or write things like that to avoid damaging one’s career.

The sentence is not even correct, water vapor is the primary greenhouse gas produced through human activity. Combustion makes more H20 than C20 and H20 is a stronger greenhouse gas too. It says produced, not how long it stays in the atmosphere.

Rich Davis
Reply to  Jimmy Joe Meeker
June 6, 2021 4:24 am

Jimmy, the liturgy doesn’t need to be scientifically accurate. The important thing is that they proclaim their faith.

gbaikie
Reply to  noaaprogrammer
June 5, 2021 11:11 pm

Well there this crazy thing called the science is settled.
Lots people are unfamiliar with this science thing- and makes them happier
to think that science doesn’t move much {it’s like unknown monster or at least
it’s annoying].

Mike
Reply to  noaaprogrammer
June 5, 2021 11:51 pm

do not change researchers’ perception of the how sensitive the Earth is to carbon dioxide”

I wonder what would?? Probably not even a 1 mile thick cover of ice over the UN building.

AndyHce
Reply to  Mike
June 6, 2021 11:54 am

It actually means “we still don’t have a clue.”

Raven
Reply to  noaaprogrammer
June 6, 2021 12:31 am

Narrator:
Scientist drills through the most potent “greenhouse gas” whilst displaying a nervous disposition about a lesser “greenhouse gas”.

fretslider
Reply to  noaaprogrammer
June 6, 2021 12:53 am

Funding?

RickWill
Reply to  noaaprogrammer
June 6, 2021 1:07 am

I would like to know more precisely why he felt compelled to say that.”

Without the ritual curtsey to the climate gods it is impossible to get a climate paper published. it is a woke world.

Serge Wright
Reply to  noaaprogrammer
June 6, 2021 3:46 am

“findings are important for improving future climate modeling but they do not change researchers’ perception of the how sensitive the Earth is to carbon dioxide, the primary greenhouse gas produced through human activity, he [Buziert] said.”

It’s a non-sensical statement. If you find out that it wasn’t as cold by a factor of 2, then it certainly must change your perception of the climate sensitivity. To claim otherwise would be a form of climate denial.

Rich Davis
Reply to  Serge Wright
June 6, 2021 4:27 am

Shhhhh! The faithful will be scandalized.

AndyHce
Reply to  Serge Wright
June 6, 2021 11:45 am

Considering the differences between east and west Antarctica today, there is no excuse for “The surprising finding is that the amount of cooling is very different depending on where you are in Antarctica.”

Willem69
Reply to  Serge Wright
June 6, 2021 7:27 pm

Nah, it means that they know the climate isn’t sensitive to CO2.

Willem post
Reply to  noaaprogrammer
June 6, 2021 5:08 am

Here is another “must-write” boiler plate statement

“We are the same amount as worried about climate change as we were yesterday”

What kind of crappola is that?

BTW, we have been and still are in an ice age which thus far has lasted about 2 million years.

Within the ice age, there were warming periods and glaciation periods.

The last on ended about 27000 y before present.

The “study” refers to THAT glaciation period.

Bill Powers
Reply to  noaaprogrammer
June 8, 2021 11:15 am

Ever since they brought Post-Modern thinking to the classroom they have turned nearly all science into political science which means you need an english to bureaucrat dictionary to translate their BS. In all cases, follow the money.

Alexy Scherbakoff
June 5, 2021 11:35 pm

Dry adiabatic lapse rate is 9.8C/km. 1C/100metres. Who will decide at what height the snow was formed and where?
Wicked winds in the Antarctic.
I think they should just shut up and play with their whatsits.

Brent Hargreaves
June 5, 2021 11:47 pm

But…. but… I thought the science was settled long ago!

Swenson
June 6, 2021 12:08 am

From the article –

“The borehole thermometry method measures temperatures throughout the thickness of an ice sheet. The Antarctic ice sheet is so thick that it keeps a memory of earlier, colder ice age temperatures that can be measured and reconstructed, said Fudge, an assistant professor in the department of earth and space science at the University of Washington.”

The man is either a fool or a charlatan. There are no “frigorific rays”. There is no “cold memory”.

There is just the slow, remorseless transport of heat through the ice cap from below. Sometimes slower, sometimes faster, depending on ice composition and thermal properties, movement, and so on.

However, trying to stop the flow of heat from the hot viscous mantle towards outer space is fruitless. It just keeps on keeping on, resulting in the slow cooling of the Earth.

GHE cultists ascertain ice temperatures at various depths. They compare these with their silly models, and in the case of any disagreement, use magic to fit reality to their models!

This kind of pseudoscience will persist as long as people keep getting paid to compose their fairy tales. Sad but true.

dk_
Reply to  Swenson
June 6, 2021 12:32 am

Swenson,
How is it that we have a mathematical study co-authored by an assistant professor named Fudge?

Phil Rae
Reply to  dk_
June 6, 2021 1:44 am

My thought, precisely! A case of karma, perhaps?

Right-Handed Shark
Reply to  dk_
June 6, 2021 3:11 am

Nominative determinism.

Rich Davis
Reply to  dk_
June 6, 2021 4:31 am

Somebody has to fudge the numbers, no?

Dave Andrews
Reply to  dk_
June 6, 2021 8:28 am

Even the comment about the same amount as worried about climate change is a fudge, because it can be taken as meaning ‘very’ or ‘not at all’.

RickWill
June 6, 2021 1:04 am

Atlantic Ocean is always at risk of going cold. Once it gets cold, it spreads from Atlantic through Antarctica to the Pacific. Indian Ocean is hardly impacted.

ralfellis
June 6, 2021 1:16 am

.
Greenhouse gasses did not feedback-force the last ice age or interglacial. We know this because: when CO2 was high the world cooled, and when CO2 was low the world warmed. The climate would not do this, if CO2 was the primary feedback agent.

Plus CO2 feedbacks are weak in the extreme. During the last interglacial warming period, the global CO2 feedback was just 0.008 W/m2 per decade, which is less energy than a bee in flight. This is insufficient to warm anything.

But at the same time, albedo feedbacks were +240 W/m2, on the (northern) ice sheets. So which will have the greater influence.

Ralph

Ozonebust
Reply to  ralfellis
June 6, 2021 3:51 am

Not only was the CO2 high, in the cooling atmoshere the molecules were closer together,
increasing the so called blanket effect.

The Dark Lord
June 6, 2021 1:49 am

 “We are the same amount of worried today about climate change as we were yesterday.”

?????? same amount of worried ???

Right-Handed Shark
Reply to  The Dark Lord
June 6, 2021 3:15 am

They are just as worried that they will lose credibility, funding and their jobs if people wake up and stop swallowing their garbage.

Bruce Cobb
Reply to  The Dark Lord
June 6, 2021 3:49 am

I am the same amount of laughing at that as you are.

Rich Davis
Reply to  The Dark Lord
June 6, 2021 4:34 am

The ways of our Lord Carbon Dioxide are mysterious. We must believe in order to understand.

Gregory Woods
Reply to  The Dark Lord
June 6, 2021 6:00 am

measured in Mann-Tons…

Tom in Florida
Reply to  The Dark Lord
June 6, 2021 6:57 am

Most of us are “the same amount of worried today about climate change as we were yesterday.” And that would be ZERO.

Ron Long
June 6, 2021 3:19 am

The lowest recorded temperature of the earth was at the Russian Antarctica base, at – 89 deg C. So the report says it was either 4 or 10 deg C colder during the last glacial cycle? And that’s not enough for them? And somehow the difference between -93 and -99 deg C is important? This is another “show me the money” report. My MSc in Geology is from Oregon State University, and I’m guessing that Professor Christo Buizert isn’t teaching “The Philosophy of Science” classes.

Geoff Sherrington
June 6, 2021 3:49 am

A search failed to find the original paper, so I have to write in terms of “I hope that the authors did this and that.”
First, the boreholes method. There are huge assumptions in this method, sadly ones that cannot be verified, easily or at all. This ice on the globe is one of the layers between a very hot interior and an energy radiating exterior. As such, over a long term, the known laws of thermal conduction apply and some energy will flow from under the ice to above it. How much can only be guessed, but it urges caution in assuming that the downhole temperatures are a measure of the temperature at deposition. Also, the very act of drilling the hole chnages the geopmetry and perturbs the heat flow assumptions.
Second, the other method they used and described as being affected by changes in height above sea level (or some other datum). If this knowledge is used in their method, there will have to have a measure of historic elevation changes. This measure also needs to have very good examination of its error bounds, which are imperative to report. If they are missing – and if error bounds on their absolute temperature estimates are not done, properly or at all, then the paper fails.
Geoff S

Tom Abbott
June 6, 2021 4:18 am

From the article: “The findings are important for improving future climate modeling but they do not change researchers’ perception of the how sensitive the Earth is to carbon dioxide, the primary greenhouse gas produced through human activity, he said.
“This paper is consistent with the leading theories about sensitivity,” Buizert said. “We are the same amount of worried today about climate change as we were yesterday.”

Me, too. 🙂

In other words, I’m not worried at all about Human-caused Climate Change.

Rich Davis
Reply to  Tom Abbott
June 6, 2021 4:37 am

Finally! We’re all on the same page.

Steve Keohane
June 6, 2021 4:42 am

I find it odd that they refer to the last interstadial as the last ‘ice age’, to the extent I question if they know what they are talking about.

Olen
June 6, 2021 7:51 am

The paper is consistent with leading theories. Is that a don’t rock the boat theory? Something useful must have resulted from the research other than ragging CO2 to death.

Wim Röst
June 6, 2021 8:19 am

That lowers the surface elevation and cooling in those areas was 4 to 5 degrees. In places where the ice sheet was much thicker during the ice age, temperatures cooled by more than 10 degrees.”

WR: Assuming the above is correct, what is the mechanism to make the highest (most central) places colder?

We know the central Antarctic has nearly constantly a high pressure area positioned above it, while the lower parts near the ocean are more influenced by low pressure areas. I suppose that central descending air comes from the lower stratosphere.

Therefore the question: was the descending (stratospheric) air more than ten degrees colder? Present lower stratospheric air is cooling as well.

Mr.
June 6, 2021 9:00 am

Did I just read that one of the authors stated “we use climate models to predict the future”?

Someone didn’t get the memo.

June 6, 2021 9:10 am

The last ice age represents a natural experiment for understanding the planet’s sensitivity to changes in greenhouse gases such as carbon dioxide, the researchers said.

It’s an astonishing feat of brainwashing that professional climate scientists can only think of temperatures on any part of earth as a pure and direct consequence of CO2. Nothing else.

Previously recognised factors affecting climate temperature which are now ignored completely include:

– Ocean circulation, chaotic oscillations thereof
– Ocean vertical mixing
– Continental movement and configuration
– Mountain uplift
– Ice albedo
– Vegetation albedo
– Vegetation interaction with humidity
– Milankovitch cycles (precession, obliquity and eccentricity).
– etc.

Tom Abbott
Reply to  Hatter Eggburn
June 6, 2021 9:21 am

“It’s an astonishing feat of brainwashing that professional climate scientists can only think of temperatures on any part of earth as a pure and direct consequence of CO2. Nothing else.”

Yes, it is astonishing.

Nick Schroeder
June 6, 2021 10:19 am

How does anybody know with accuracy or precision what Antarctica was like during the last ice age?

What is the consensus preferred combination of tea leaves, Ouija boards, Tarot cards and Magic 8 balls?

observa
Reply to  Nick Schroeder
June 7, 2021 6:50 am

“How does anybody know with accuracy or precision what Antarctica was like during the last ice age?”

You don’t have to go back that far without a shred of evidence. You just imagine whatever you like and what you want to believe to fit your lefty narrative-
‘Devil devil’: The sickness that changed Australia (msn.com)
With only penguins in Antarctica you have absolutely free reign to project back to your heart’s content and believe whatever you like and nobody can prove otherwise. Then a like minded lefty media to promote such urban myths will do the rest although some pal review to kick it off certainly helps. Variola CO2 it’s all the same to them and their conspiracy theories.

Walter Sobchak
June 6, 2021 12:09 pm

“We use climate models to predict the future, and those climate models have to get all kinds of things correct. One way to test these models is to make sure we get the past right.”

No. It just means that you are tuning your parameters in a certain way. You have no idea how they will change in the future.

The function 1/x will fit a straight line pretty well for x>1000. But if X<1 it takes off and goes the other way. Hindcasting doesn’t mean you have the right equations or the right parameters.

Last edited 9 days ago by Walter Sobchak
H.R.
June 6, 2021 2:35 pm

What?!?

It’s better than we thought?

Color me confused.

dk_
June 6, 2021 9:01 pm

Cristo Buziert, Phd Geophysics, is listed at Eurekalert as responsible for the news release, so this isn’t strictly a ghost written propaganda sheet from a green goon outlet like we’ve seen before. In this news release, he is billing himself as a climate change expert. His Oregon State web page links to an April 2016 pre-publication letter published at Geophysical Research Letters _Variable relationship between accumulation and temperature in West Antarctica for the past 31,000 years_

Does this mean that his _Science_ publication of the research has been in the publication pipeline for five years?

The earlier letter concludes with
“Model-based simulations which indicate an offset to sea-level rise from increased Antarctic accumulation should be treated with caution. ”

But since the conclusion is that there is about a 6 degree C difference between high and slightly lower altitudes of some portion of the ice cover, and we’re talking at or near 40 below at either scale, it is kind of hard to be really upset about it. What Cristo has done is poke a small hole in some number of other models with an imperfect model of his own.

ATheoK
June 7, 2021 7:05 pm

“This is the first conclusive and consistent answer we have for all of Antarctica,” said Buizert, an Oregon State University climate change specialist. “The surprising finding is that the amount of cooling is very different depending on where you are in Antarctica. This pattern of cooling is likely due to changes in the ice sheet elevation that happened between the ice age and today.”

Understanding the planet’s temperature during the last ice age is critical to understanding the transition from a cold to a warm climate and to modeling what might occur as the planet warms as a result of climate change today, said Ed Brook, a paleoclimatologist at OSU and one of the paper’s co-authors.

Antarctica is particularly important in the climate system,” Brook said. “We use climate models to predict the future, and those climate models have to get all kinds of things correct. One way to test these models is to make sure we get the past right.

answer we have for all of Antarctica”, they used seven boreholes to calculate an Antarctica average temperature?
During which century?

likely due to changes in the ice sheet elevation”, Likely!?
Speculative silliness.

We use climate models to predict the future”, none of which have demonstrated any accuracy. A condition that invalidates their assumptions.

One way to test these models is to make sure we get the past right.”, fudging models? Kludging individual proxy borehole temperatures into a fudged paleo average?
How is a paleo climate model tested? What parameters are fed to simulate what conditions?

Just more folks fudging systems so that they match assumed data to better support inaccurate model predictions.

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