Wikipedia says:
The Eemian was an interglacial period which began about 130,000 years ago and ended about 114,000 years ago. It was the second-to-latest interglacial period of the current Ice Age, the most recent being the Holocene which extends to the present day. The prevailing Eemian climate is believed to have been similar to that of the Holocene.
Last Interglacial Arctic Warmth Confirms Polar Amplification of Climate Change
by the Cape Last Interglacial Project Members
Guest summary by Peter Hodges of the Paper at:
http://chubasco.fis.ucm.es/~montoya/cape_lig_qsr_06.pdf
It is widely accepted that the last interglacial was much warmer than the current. Forests reached the Arctic ocean across most of Eurasia, Scandinavia was an Island due to higher sea levels, and hippos swam in the Thames. As a basic introduction to the subject the Wikipedia http://en.wikipedia.org/wiki/Eemian entry is well worth a quick read.
The paper concerned, however, offers a comprehensive survey of literature concerning the Eemian interglacial, focused on the Arctic. The literature cited by the authors consists almost entirely of data from actual empirical research as opposed to “data” from model outputs. There are also four pages of citations for anyone who wishes to check the authors sources, or simply dig deeper. For those who have time, I highly recommend reading the paper in its entirety.
For those don’t have the time, the authors offer a concise summary in their conclusion:
“Quantitative reconstructions of LIG (Last InterGlaciation) summer temperatures suggest that much of the Arctic was 5C warmer during the LIG than at present… Arctic sea ice was reduced to a greater extent in the LIG than during the early Holocene due to both greater summer insolation and the larger flux of relatively warm Atlantic surface water into the Arctic Ocean during the LIG than at any time in the Holocene.”
The fundamental factor which drove Eemian temperatures higher than those in the Holocene was dramatically higher summer insolation. Northern Hemisphere insolation during the Eemian was higher than today, while Southern Hemisphere summer insolation was lower than today. Most importantly, “By the time sea level reached present in the Holocene (6 ka), the high latitude Northern hemisphere summer insolation anomaly was ca 15Wm_2, whereas at the comparable time in the LIG (130 ka) it was ca 45Wm_2, three times as large.”
How much warmer were Eemian summers? Evidence from the surveyed literature paint a consistent picture. The Atlantic-Siberian sector was typically 4-8C warmer, and Beringia 2-4C warmer. Alaska was 0-2C warmer in summer, but colder in winter. NE Canada and Greenland registered at least 5C warmer in summer. Temperate zones adjacent to the Arctic (and the planetary average) registered roughly 0-2C warmer than the present. This was apparently enough of a difference to facilitate vastly different plant and animal distributions. In some areas plant zones move 1000k north. Trees grew as for north as the Arctic Ocean and hippos swam in the Thames.
The authors argue that the polar region temperature anomalies were so much greater than the planetary average due to positive feedbacks. The warmer Arctic temperatures greatly reduced snow, land and sea ice cover relative to present. This decreased the albedo on land and sea, which resulted in warmer temperatures. While Arctic sea ice cover is rigorously debated, “the available data suggest that sea ice remained through the summer in the central basin.”
There would have been however, much more estensive leads and the ice in places was at least 800km north of the present summer extent. Reduced sea ice and increased meridianal circulation of warm, salty Atlantic waters into the Arctic dramatically warmed Arctic waters relative to the present which then allowed for a much warmer northern Eurasia.
There does not appear to be a consensus on exact ice cover in Greenland. Southern Greenland may have been ice-free or almost ice free while modeled estimates for the Northern Ice sheet are that it was reduced by 20-50%. There is at least solid evidence that some northern sites such as Dye-3 were not glaciated during the Eemian.
While the paper argues that there is indeed “polar amplification of climate change”, the conclusion is again worth quoting:
“The observational records of 20th century warming are not in perfect accord with model projections…The paleoclimate record is more direct… Most of the warming occurred in summer months, whereas model projections indicate winter warming should dominate.”
The authors then illustrate the effects of “polar amplification” during glaciation: While global temperatures are estimated to be roughly 6-8C below present at last Glacial Maximum, Arctic cooling as evidenced by Greenland Ice Sheet boreholes was 25C.
Also Tim I don’t get the impression they “disavow” models. Did you really mean that? They just point out that there is not a perfect match between the models and the proxies. Doesn’t seem too surprising to me as it was 150,000 years ago.
LazyTeenager says:
September 10, 2010 at 1:44 am
I am interested in the conditions in the rest of the world at that time. Was the rest of the land world one big desert or was this moderated by more water vapour leading to moist conditions or more variable conditions.
Well there is this information that might interest you:
Reconstruction of North America during last Ice Age
http://www.esd.ornl.gov/projects/qen/nercNORTHAMERICA.html
ICE AGE MAP http://www.esd.ornl.gov/projects/qen/NAL2215.gif
I only had to read to the end of the abstract to find the quaint but requisite genuflection to warmist superstition. I think the authors deserve thanks for saving our time.
Bill says:
September 10, 2010 at 1:08 am
Can anyone advise if there is any authoritive comment on Antarctic temperature in the Eemian as well.
_________________________________
Yes there seems to be according to this article:
http://www.telegraph.co.uk/earth/environment/climatechange/6606227/Antarctic-temperatures-between-ice-ages-6C-warmer-than-today.html
They came up with 6C warmer too.
There is also the Vostok Ice Core data: http://3.bp.blogspot.com/_cHhMa7ARDDg/SmDoZBIkB3I/AAAAAAAABAc/KkUzrz2abwI/s1600-h/Vostok-140Kc.jpg
Ralph says:
September 10, 2010 at 1:57 am
Interesting thesis, but they do not explain the basic mechanics of this event. They say that summer insolation in the N Hemisphere was increased by 11%, through “orbital parameters aligning”.
What parameters?….
______________________________________________________
They are talking about the Milankovitch cycle.
There is this study for the Holecene:
Temperature and precipitation history of the Arctic
“..Solar energy reached a summer maximum (9% higher than at present) ca 11 ka ago and has been decreasing since then, primarily in response to the precession of the equinoxes. The extra energy elevated early Holocene summer temperatures throughout the Arctic 1-3° C above 20th century averages…”
But if it was that much warmer in the Arctic during the Eemian, and also so much warmer about 7000 years ago – why do we still have Polar Bears?
Shouldn’t they, ahem, have drowned or starved to extinction twice already?
Who saved them? Al Gore wasn’t around then, was he?
😉
Fred says:
September 10, 2010 at 2:55 am
So I guess this website has shifted from saying….
___________________________________________
And another Real Climate/Climate Progress faithful shows he can not grasp the Header:
Commentary on puzzling things in life, nature, science, weather, climate change and recent news by Anthony Watts. He is so used to propaganda he become confused and alarmed at anything “Off Message”
Best hurry back to Real Climate and Climate Progress, Fred before you have an anxiety attack.
Wow! I had NO IDEA that humans were driving SUVs back then. Look at the awful things we did to poor mother Earth!
How do you know that buddies?, did you use a joystick instead of a hockey stick?.
Some time ago I looked at the various Milankovitch cycles and came to the conclusion that the ones that appeared to have most effect were those associated with tilt rather than distance from the sun. This tilt varies the length of the seasons by up to a month giving a far greater average insolation for one hemisphere or the other when averaged over the year.
This report states that the Arctic amplification is mainly in the summer rather than the winter predicted by the models. I do not understand why the models predict winter warming amplification at the poles. In my mind reduced winter sea ice cover would leave more open water and therefore more evaporation and radiation loss. There is little or no sunlight so the effect of lower albedo has got to be cooling. In the summer any reduced ice cover would lead to reduced albedo and both increases in absorption and radiation. However the big difference is that on land an increase in insolation would lead to a large rise in temperature. In fact the temperature would rise until the increase in outgoing radiation balanced the increase in insolation. This is a daily occurance in the desert where the temperature beween day and night varies by up to 50K. A lesser variation balances the average seasonal change in insolation.
The sea and ice behave differently. The sea has the option of subducting warm water to create hot pools and also evaporates to eventually fall as rain in colder locations. These reduce the temperature excursions at the surface.
These effects mean that the some of any increased insolation can and indeed must be stored. The same is true for ice where the melting effect takes a huge amount of latent heat (80 calories per gram in my out of date units!) Whilst this melting takes place there is an albedo change but little temperature change, reducing the increase of radiation into space compared with melting snow on land.
The earth’s radiation balance has to be maintained over the long term but it is probably thousands of years before equilibrium is reached after a Milankovitch cycle change. During those thousands of years the non balanced portion is stored. The reverse happens during a cool cycle because the sea continues to radiate heat even when the insolation drops and will do so for thousands of years before a new balance is reached. During this period the warm pools will vanish and the ice build up during this time will also release latent heat and reduce evaporation and stop the world cooling as much as it would if it were all land.
In my mind it is strange that the climate scientists say that the Milankovitch cycles cannot explain all the temperature excursions over the millenia. In my mind the changes in insolation and season length are more than enough to explain the changes in temperature. Indeed by the arguments above I would expect even greater temperature changes if the earth were predominately land.
For these reasons I have my own theory about the interglacial periods. It is only a guess but I believe it starts with positive insolation in the Southern Hemisphere building large reserves of heat in the warm pools in the large southern oceans and melting the ice around Antarctica. Thus this half of the cycle leads to little increase in temperature but a large increase in heat stored or heat used to melt ice. When the cycle moves to the northern hemisphere the greater land mass and smaller ice coverage means that the storage effect is less and the temperature increase has therefore got to be greater. Thus if we are looking at proxies for global average atmospheric temperature I would expect them to be correlated with high insolation in the Northern Hemisphere. If we are looking at average sea temperatures I would expect this to correlate with high insolation in the Southern Hemisphere.
By the way ice core data is an atmospheric proxy since it measures the air disolved in the ice crystal which eventually fell as snow. The best ice core research compensates for this when it calculates the surface temperature.
Anyone have any data on this?
The Arctic ice measurements – don’t the use a baseline of 1979? that was a high,
when the satellite era began? So we really don’t know what is “normal”?
Just asking…
tom says: September 10, 2010 at 6:58 am
Hey Tim…when you say observational data do you mean proxies?
No, alien observed thermometers. ;~P. Of course proxies. Granted, proxies have their own problems and interpretations, but they are at least something discreet, tangible, and with open methodology.
tom says: September 10, 2010 at 7:08 am
Also Tim I don’t get the impression they “disavow” models. Did you really mean that? They just point out that there is not a perfect match between the models and the proxies. Doesn’t seem too surprising to me as it was 150,000 years ago.
“The observational records of 20th century warming are not in perfect accord with model projections…The paleoclimate record is more direct… Most of the warming occurred in summer months, whereas model projections indicate winter warming should dominate.”
Tom, my interpretation of this conclusion is:
The paleoclimate record ( from multiple sources) indicates most of the warming occurred in the summer months.
Current model projections indicate winter warming.
If my interpretation is correct and you concur, what word other than disavow would you select?
It never fails to amaze me how different people can look at the same study and draw completely different conclusions. The causes of the Eemian interglacial was astronomical (i.e. Milankovitch cycles), as likely was the Holocene Optimum. Todays warming has no such Milankovitch associated cause, and as such, you would expect the dyanamics of the current warming to be somewhat diffferent as the cause is different. CO2 levels during the Eemian and the Holocene optimum were both lower than today, and IF the 40% rise in CO2 over the past few hundred years is indeed the cause of the current warming period, then you would expect the global effects and seasonal effects of the current warming to be different, as appears to be the case thus far.
Record Arctic sea ice minima? Uhm, I don’t believe you have enough data to say that there has been any records. We just don’t know what the sea ice was like only 600 years ago let alone 6000 years ago. The ice currently in the Arctic could well be quite typical for interglacial periods. To say that today’s Arctic ice is atypical in any way is an intellectually arrogant statement in my opinion because as far as I can tell, there is no proof that the statement is true. We have much evidence pointing to the fact that Arctic ice was much less in this interglacial and in others past than it is today.
We see some variation, yes, but to say it is atypical is a bit much.
EFS_Junior says: at 2:30 am “I mean two articles/ . . . must mean something.”
It means if one wants to read truth about climate knowledge there is no better place than WUWT.
Fred says:
September 10, 2010 at 2:55 am
Fred,
As you are the most recent to make a comment such as “So I guess this website has shifted . . .”, maybe you can explain why people make such statements. I do not understand such comments. Someone publishes a paper and WUWT links to it and summarizes it. Later, another paper appears, then another, then another. In some cases they say opposite things. We read them and learn, we try to understand how they relate to our current global and maybe regional situations. To say that “this website has shifted” its viewpoint seems a purposeful misdirection on the part of the person writing this.
I agree than many people reading here have wondered why there is so much fuss over the amount of Arctic Ocean ice. If one believes that Earth is dynamic maybe they have a point. If one believes the recent past, say 40 or 50 years ago, was an optimum, well then, that’s an interesting viewpoint also. A kerfuffle does not seem too surprising.
Years ago at Forbes Field in Pittsburg the news paper vendor would walk the aisles yelling “Something to read, something to sit on. Only a quarter.” Some choice! If you didn’t like the contents, too bad, you’d already paid. Now it is free; you can’t sit on it, but you could still print it out and line the bird cage with it – if you find it offensive. I find I learn things when I listen to different backgrounds and ideas, and because WUWT posts and posters provide a wide range of both I, and may others, come here. With respect to the topic of this current post you attribute a “shift” for the website that I don’t think exists. WUWT?
Vuk etc. says:
September 10, 2010 at 1:21 am
So, when the power from the mains lower the jet streams migrate equator wards, as in Birkeland’s terrella experiment:
Chapter VI. On Possible Electric Phenomena in Solar Systems and Nebulae:
With a constant magnetization, the zones of patches will be found near the equator if the discharge-tension is low, but far from the equator if the tension is high.
Lance says:
September 10, 2010 at 4:49 am
An interesting train of thought, how does it relate to flash frozen mammoth meat?
R. Gates,
There was no evidence of significantly inflating CO2 levels in the atmosphere during the Eemian warm epoch.
Not only that Plants and animals flourished in the expanded biosphere.Humans lived through it too.
You need to reconsider your overt attachment to CO2 as a warming driver.It never showed up in the previous warming epoch and not in the current one either.Most of the warming up time in the Holocene ended around 8-10,000 years ago.While CO2 was around 200-220 ppmv.
The warmest part of the present interglacial was over 7,000 years ago and never reached since then.
Consider this chart and see just how irrelevant CO2 is as a climate driver:
http://globalwarmingskeptics.info/forums/thread-188-post-3123.html#pid3123
Here this chart shows that most of the true warming ended around 10,000 years ago and has been oscillating ever since in a small band:
http://globalwarmingskeptics.info/forums/thread-188-post-3130.html#pid3130
There are no CO2 warming signatures at all shown on the charts.
thefordprefect says: “…The abundant fertility of this region was also the reason why Eric the Red chose to live in South Greenland in around 985 AD, after he was outlawed from Iceland.”
If he really was a Red, then it was a fine idea to outlaw him.
Well Tim, see, that’s the thing. It seems like a lot of the people here didn’t like proxy data before but in this study it seems like a lot of ’em do. So I can’t help but wonder what was wrong with the proxy data earlier or what is better about this proxy data.
As to disavow… I’ll have to disagree with your interpretation. When I look up the definition of the word I get things like: “To disclaim knowledge of, responsibility for, or association with.” Now in the paper all they say is that the models are “…not in perfect accord with model projections,…”. That’s hardly a disavowal. Then, on the same page they actually seem to use the results of model data to support one of their statements: “Climate modeling of the LIG also underscores the importance of snow, ice and vegetation feedbacks that amplify insolation-driven Arctic warmth (Crucifix and Loutre, 2002; Otto-Bliesner et al., 2006).” So I just can’t believe they have disavowed the models based on what I have seen so far.
What I see is a paper that relies heavily on proxy data to come to a conclusion. They also do a very short compare and contrast of their results with some of the results of the model data.
Tim Clark,
discreet != open
😉
Or did you mean discrete?
take a good hard look at that insolation graph and see where we are on that sinosoidal curve…
what i took away from the paper is that in spite of temperatures up to 8c warmer than present, and something like the gulf stream basically cutting from england right across the top of eurasia, there was still summer ice in the arctic basin. so no need to panic about a dubious .7c and sst anomalies in the tenths of a degree.
and arctic ice was vastly reduced – but the polar bears and narwhals were fine, and the climate roughly stabilised within certain bounds…no scary tipping point was passed.
sounds to me like Eemian planet Earth would have been a way cool place to be…..
sunsettommy says:
September 10, 2010 at 10:25 am
R. Gates,
There was no evidence of significantly inflating CO2 levels in the atmosphere during the Eemian warm epoch.
_________
I know that. Current CO2 levels are far higher than they’ve been for at least 400,000 years, and likely even longer. The Milankovitch cycles are the most likely driver behind the Eemian and the Holocene Optimum, and CO2 levels were about the same during both at about 260-280 ppm. Essentially what the planet has seen over the past 250 years or so is a human CO2 volcano whereby humans are releasing large amount of CO2 via the burning of fossil fuels in a geologically short period of time. The current warming may or may not be related to this, but I think it far more likely than not that it is, as there is currently no other known cycles to account.
In short, the warmth during the Eemian or the Holocene Optimum in no way disprove current AGW from CO2 release– and if anything, they confirm the basic notion of polar amplfication during warm periods just as GCM’s predict will happen with AGW.
oh ya.
i also noted the authors conclusion that the “amplifications” produced in GHG based GCM’s failed to match the evidence from actual observed amplifications